Emerging Trends in The Social and Behavioral Sciences

Evolutionary Perspectives on Animal and Human Personality

Item

Title

Evolutionary Perspectives on Animal and Human Personality

Author

Manson, Joseph H.

Fairbanks, Lynn A.

Research Area

Development

Topic

Evolutionary Bases of Development

Abstract

Among many nonhuman animals, individuals differ consistently in their response tendencies (e.g., shy vs bold) across multiple contexts. Researchers have tested evolutionary hypotheses accounting for these phenomena, and have also begun exploring evolutionary explanations for human personality variation. For evolutionary biologists, a trait's significance lies in its effects on fitness, that is, the lifetime reproductive success of individuals who bear the trait, including indirect effects through the reproductive success of genetic relatives. Recent evolutionary personality research has pursued several alternative theoretical lines of inquiry: balancing selection models explore whether optimal levels of personality traits vary across time, space, or trait frequency distribution; mutation‐selection balance models propose that selection for a single optimum personality configuration is undermined by mutations at multiple genetic loci; and facultative calibration models hold that personality trait levels are adjusted, during individual development, to other characteristics that affect social bargaining power. A promising general approach links personality variation to variation in life history strategy, that is, the allocation of effort among the competing demands of growth, somatic maintenance, mate acquisition, and parental investment. Emerging areas of research include relationships between personality variation and biological fitness in humans and other primates; the extent to which personality trait levels are adjusted based on individual condition; the degree to which situational flexibility varies among individuals; and whether proposed structural models of personality, such as the human five‐factor model (extraversion, neuroticism, agreeableness, conscientiousness, and openness to experience) are species‐typical or are affected by variable ecological and social conditions.

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Identifier

etrds0124

extracted text

Evolutionary Perspectives on Animal
and Human Personality
JOSEPH H. MANSON and LYNN A. FAIRBANKS

Abstract
Among many nonhuman animals, individuals differ consistently in their response
tendencies (e.g., shy vs bold) across multiple contexts. Researchers have tested
evolutionary hypotheses accounting for these phenomena, and have also begun
exploring evolutionary explanations for human personality variation. For evolutionary biologists, a trait’s significance lies in its effects on fitness, that is, the lifetime
reproductive success of individuals who bear the trait, including indirect effects
through the reproductive success of genetic relatives. Recent evolutionary personality research has pursued several alternative theoretical lines of inquiry: balancing
selection models explore whether optimal levels of personality traits vary across time,
space, or trait frequency distribution; mutation-selection balance models propose that
selection for a single optimum personality configuration is undermined by mutations at multiple genetic loci; and facultative calibration models hold that personality
trait levels are adjusted, during individual development, to other characteristics
that affect social bargaining power. A promising general approach links personality
variation to variation in life history strategy, that is, the allocation of effort among the
competing demands of growth, somatic maintenance, mate acquisition, and parental
investment. Emerging areas of research include relationships between personality
variation and biological fitness in humans and other primates; the extent to which
personality trait levels are adjusted based on individual condition; the degree
to which situational flexibility varies among individuals; and whether proposed
structural models of personality, such as the human five-factor model (extraversion,
neuroticism, agreeableness, conscientiousness, and openness to experience) are
species-typical or are affected by variable ecological and social conditions.

INTRODUCTION
Traditional evolutionary approaches to animal behavior focused on optimal
responses (within developmental and contextual constraints) to adaptive
challenges such as predator encounters and contests over mates. Different
responses by different individuals of the same age, sex, and circumstances
were attributed to measurement error or to statistical “noise.” In the
past 15–20 years, inspired by pioneers such as Joan Stevenson-Hinde
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

(Stevenson-Hinde & Zunz, 1978), D.S. Wilson (Wilson, Clark, Coleman, &
Dearstyne, 1994), and Samuel Gosling (Gosling & John, 1999), researchers
have confirmed and extended the intuitions of pet owners and zookeepers
that (i) individual animals’ responses are, to a substantial extent, consistent
across situations and over long periods of time and (ii) individuals differ
in these response tendencies. These two features (within-individual consistency and between-individual differences) serve as the defining features
of personality for researchers of animal behavior. A closely related concept
developed by Andrew Sih (Sih, Bell, Johnson, & Ziemba, 2004), the behavioral
syndrome, emphasizes within-individual consistency across contexts—for
example, an individual may show above-average aggressiveness toward
predators, same-sexed rivals, and prospective mates.
The widespread observation of animal personality poses two theoretical
puzzles. First, why has not natural selection equipped animals to respond in
the fashion best suited to the present situation, rather than being constrained
by a consistent response style that may lead to suboptimal choices? Second,
given that some personality variation is a product of genetic variation among
individuals, how does natural selection maintain this variation? In general,
selection is expected to eliminate variation in traits relevant to biological fitness, that is, traits that affect an individual’s ability to survive, reproduce,
and pass its genes on to future generations. Inclusive fitness includes an individual’s own reproduction as well as its effects on its relatives’ reproduction,
devalued by the proportion of genes shared with that relative. Research into
the puzzles posed by animal personality has proceeded in parallel with a
small but growing body of evolutionarily based research on human personality variation.
FOUNDATIONAL RESEARCH
METHODS IN THE STUDY OF ANIMAL PERSONALITY
Two general methods have dominated research on nonhuman animal personality. Standardized tests expose animals to a situation designed to elicit
variable responses. For example, temporarily captive songbirds are videotaped in a room containing artificial trees, and observers record how many
trees are visited by each individual (Dingemanse, Both, Drent, van Oers, &
van Noordwijk, 2002). Bighorn sheep are scored as more bold if they are
more willing to enter a corral trap baited with salt, and as more docile if
they struggle less during handling by humans (Réale, Gallant, Leblanc, &
Festa-Bianchet, 2000). Novel objects or conspecifics may be placed in captive
animals’ enclosures, and their reactions systematically coded.

Evolutionary Perspectives on Animal and Human Personality

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The rating method uses questionnaires containing 20–60 adjectives (e.g.,
active, popular, and irritable) on which experienced observers (e.g., zookeepers and field assistants) rate each animal on a multipoint scale. Statistical
techniques assess inter-rater reliability, and reduce the set of adjectives to a
smaller number of general factors or dimensions of variation (Freeman &
Gosling, 2010).
PROXIMATE AND DEVELOPMENTAL STUDIES
OF ANIMAL PERSONALITY
A large body of research has used animal models of human psychiatric and
behavioral disorders to focus on the proximate (e.g., physiological) and
developmental mechanisms underlying personality variation. For example,
adverse early experience, particularly separation from the mother, has been
linked to emotional dysregulation and anxiety-related traits in nonhuman
mammals (Levine, 2005). Genetic polymorphisms in neurochemical pathways have been shown to increase risk for antisocial behavior in humans
and nonhuman animals, and these “risk” genes interact with adverse
environments to increase vulnerability for behavioral disorders (Caspi &
Moffitt, 2006; Soumi, 2011). Individual differences in personality traits have
also been related to immune function and infectious disease susceptibility
(Capitanio, 2011a). These and other studies provide valuable information
about the proximate factors involved in personality variation, but they do
not explain how “risk” genes for fitness-reducing personality traits persist
in populations. For this, we turn to models from population biology.
PERSONALITY AND BIOLOGICAL FITNESS: FOUNDATIONAL STUDIES
Several different ideas have been proposed to explain how personality variation can be maintained in populations. Some researchers, beginning with
Wilson et al. (1994) have drawn hypotheses from the concepts of balancing
selection and trade-offs. The optimal level of a trait may vary geographically,
between generations, over an individual’s lifespan, between the sexes, or
as a function of the existing distribution of trait levels in a population.
As an example of the last phenomenon, frequency-dependent selection, if an
animal population contains a mix of foragers (who harvest food from the
environment) and scroungers (who parasitize the efforts of foragers), then
scroungers are likely to have a higher net energy intake than foragers when
scroungers are rare, but not when they are common (Barnard & Sibly, 1981).
Dingemanse, Both, and Drent (2004) have found that a songbird, the
great tit, shows considerable variation in the speed with which individuals
explore a novel environment. Fast explorers are also more risk-prone than

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

slow explorers. A multiyear study in the wild showed that during years of
food abundance and resultant high survival rates, fast-exploring adult males
and slow-exploring adult females survived at the highest rates, whereas
during years of scarcity, slow-exploring adult males and fast-exploring adult
females prevailed. Researchers attributed the results to the sex-differentiated
effects of resource availability on the intensity of within-sex competition. In
both sexes, fast-exploring individuals outcompeted slow-exploring individuals for access to winter food. Only males defend territories, and male–male
competition for these territories was greatest when many males survived
a bountiful winter. Females were subordinate to males in competition for
food, and were therefore at greater risk of death during winters of scarcity.
Similarly, complex relationships between personality and biological success have been found or suggested for other species. Réale and colleagues
(Réale & Festa-Bianchet, 2003; Réale et al., 2000) have shown that bolder wild
female bighorn sheep had higher fitness than shy females, and more docile
females had higher fitness than less docile females. However, boldness
and docility were negatively correlated, preventing natural selection from
shaping an optimal level of both personality traits. Among male rhesus
monkeys (Howell et al., 2007) and vervet monkeys (Fairbanks et al., 2004),
more impulsive, risk-prone individuals are at greater risk of injury before
reaching adulthood, but those who survive attain higher dominance rank
following transfer to a new social group in late adolescence. This pattern
suggests a trade-off between a higher risk of early death and a larger
reproductive payoff for survivors later in life. A meta-analysis of data from
10 mammal species and 2 fish species revealed that bolder individuals,
particularly males, experienced greater reproductive success but diminished
survival prospects (Smith & Blumstein, 2008).
Researchers of human personality have proposed possible fitness trade-offs
associated with personality variation, but relevant empirical studies remain
rare. The most widely accepted, although still controversial, structural
model of human personality posits five independently varying dimensions
(five-factor model or FFM) (Costa & McCrae, 1995; Digman, 1990): extraversion (gregariousness, activity, positive emotions); neuroticism (negative
affect, e.g., anxiety, anger, and depression) or its inverse emotional stability;
agreeableness (altruism, trust, and straightforwardness); conscientiousness
(order, self-discipline, and achievement striving) and openness to experience
(including openness to ideas, feelings, aesthetics). Nettle (2005) found that
among British adults, self-reported Extraversion was positively correlated
with number of sexual partners, but also with the probability of experiencing
hospitalization for accident or illness, suggesting a personality-mediated
trade-off (at least in ancestral human environments) between production
of offspring and individual survival. Relationships of human personality

Evolutionary Perspectives on Animal and Human Personality

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variation to fitness might encompass interactions among traits, as in some
of the nonhuman animal systems. Among Australian women, the largest
completed family sizes were found among those who were either high in
extraversion and low in neuroticism or else low in extraversion and high in
neuroticism (Eaves, Martin, Heath, Hewitt, & Neale, 1990).
CUTTING-EDGE RESEARCH
Evolutionary personality theory has recently begun to catch up with the
rapid proliferation of empirical research. Several theorists have built on the
basic idea that personality variation is tied to variation in life history strategy,
that is, the allocation of effort among the competing demands of growth,
somatic maintenance, mate acquisition and parental investment (Stearns,
1992). For example, Wolf et al. (2007) have developed an evolutionary
model in which individuals may explore their environment thoroughly,
trading off some near-term reproduction for longer-term increased access
to higher-quality resources, or explore superficially, maximizing near-term
reproduction at the expense of future resource gains. Over a wide range of
starting conditions, a mix of stable personality configurations emerges, in
which thorough environmental exploration is linked with risk aversion in
both anti-predator and intraspecific aggressive contexts.
As an alternative to hypotheses that invoke balancing selection and
trade-offs to propose that a wide range of personality types is adaptive, some researchers have attributed human personality variation to
mutation-selection balance. In this view, natural selection favors a particular
human personality configuration, to which a large number of genetic loci
contribute, while mutations undermine this configuration. First developed
by Miller to explain persistent variation in intelligence (Miller, 2000) and
heritable mental illnesses (Keller & Miller, 2006), the mutation-selection
balance theory has been more controversially applied to normal personality
variation by Rushton, Bons, and Hur (2008). The hypothesized general factor
of personality (GFP) is based on a proposed positive correlation among
extraversion, agreeableness, conscientiousness, openness, and emotional
stability. Figueredo et al. (2005) argue that behavioral propensities function
best as coordinated sets of traits, and propose that people pursuing a slower
life history (late onset of reproductive activity, high investment in a small
number of children, etc.) are higher on the GFP. Another evolutionary
approach, proposed originally by Tooby and Cosmides (1990) and developed further more recently by Lukaszewski and Roney (2011), proposes
that human personality variation (e.g., in extraversion) is calibrated during
development to individual characteristics (e.g., physical attractiveness and
formidability) that affect social bargaining power.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Empirically, a recent study found that much of the heritable variation in
traits resembling extraversion and emotional stability reflects the combined
effects of many different low-frequency gene variants, as predicted by the
mutation-selection balance hypothesis (Verweij et al., 2012). On the other
hand, a study of traditional Senegalese villages found evidence for trade-offs
and stabilizing selection in women’s emotional stability: less stable women
produced more children, but more stable women’s children were healthier (Alvergne, Jokela, & Lummaa, 2010). The first large-scale published
research on personality variation in a small-scale (hunter-horticulturalist)
society (Gurven, von Rueden, Massenkoff, & Kaplan, 2013) found that a
two-factor model (prosociality and industriousness) produced the best fit
to the data, casting doubt on the universality of the FFM. Among men,
reproductive success was positively correlated with Industriousness and
with the FFM extraversion, conscientiousness, openness, and emotional
stability dimensions, whereas among women, relationships between
personality dimensions and fitness varied geographically (Gurven, von
Rueden, Stieglitz, Kaplan, & Rodriguez, in press). Among the Senegalese
studied by Alvergne et al. (2010) and among the recently settled former
hunting-gathering Ache of eastern Paraguay (Bailey, Walker, Blomquist,
Hill, & Hurtado, 2013), more extraverted men had higher reproductive
success.
Recent studies of nonhuman animals have explored dimensions of personality variation beyond the boldness and aggressiveness continua that
dominated earlier research. Among male great tits, competitive ability is
negatively correlated with innovative problem-solving ability (analogous to
human conscientiousness and/or openness) (Cole & Quinn, 2012). A model
of the evolution of trust and trustworthiness suggests that social awareness (i.e., monitoring of third party interactions) and within-individual
consistency in trustworthiness (a component of human Agreeableness)
can coevolve, each trait selecting for increases in the other (McNamara,
Stephens, Dall, & Houston, 2008).
KEY ISSUES FOR FUTURE RESEARCH
A number of key questions remain unresolved and will dominate evolutionary research into personality (both human and nonhuman) in the coming
years:
1. To what extent is personality variation associated with variation in
fitness? Models of balancing selection propose that, at least over wide
spatial and/or temporal scales, different levels of personality traits
have equal fitness. Alternatively, personality trait levels are expected to

Evolutionary Perspectives on Animal and Human Personality

2.

3.

4.

5.

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correlate consistently with fitness (e.g., in humans, higher neuroticism
with lower fitness) in models of mutation-selection balance or adaptively flexible personality in response to variable fitness-relevant states
such as body size or parasite infection. Some personality configurations
might represent a disadvantaged individual “making the best of a bad
job,” in which case low fitness is expected (although not as low as
would occur if an individual in poor condition adopted a personality
configuration appropriate to good condition).
A closely related question is the extent to which personality variation
is condition-dependent (i.e., state-dependent). An alternative to statedependent models regards personality variation as driven largely by
variation in genotypes that affect psychological processes directly via
neural and/or hormonal machinery (e.g., androgen receptors).
What are the relative impacts on personality variation of early developmental events that may cue life prospects (e.g., maternal condition
during gestation and father absence during human childhood) versus
adult health, social status, threats, and opportunities?
What is the relationship between variation in dimensions such as
shy-bold, on the one hand, and individual variation in cross-situational
plasticity (e.g., the capacity to vary one’s level of boldness as a function
of context)? A promising, recently developed model by Dingemanse,
Kazem, Réale, and Wright (2010) integrates both forms of variation
using the concept of behavioral reaction norms. Among other advantages,
this concept facilitates the investigation of individual × environment
interaction, that is, the nonrandom distribution of personality types
across habitats.
How and why do different dimensions of personality variation covary
in different species and in different human populations?

Pursuing these research questions in nonhuman animals will entail
overcoming some formidable practical obstacles. Measuring lifetime fitness,
as well as its components (time to sexual maturity, age-specific survival
and fertility rates, offspring survival rates, etc.) in varied environments in
long-lived nonhuman animals in the wild is a slow and expensive endeavor.
However, personality measurement in wild populations promises to become
easier through the use of (i) standardized situational tests on temporarily
captive individuals and (ii) observer rating methods based on naturally
occurring behavior. The latter have demonstrated sufficient reliability and
validity in captive settings (e.g., Capitanio, 2011b) to justify their use in wild
populations (e.g., Manson & Perry, 2013), and such research will become
more common and fruitful. Some of the ecological variables (e.g., food

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abundance, predation risk, and parasite prevalence) proposed by modelers to affect personality variation are measurable using well-established
methods, and new methods are currently being developed for noninvasive
measurement of metabolic and hormonal variables in large mammals in
the wild. Personality researchers studying captive or semi-free-ranging
animals lack the opportunity to measure ecological variables or to collect
generalizable data on fitness variation, but they have easier access to certain
proxies for fitness (e.g., growth rates) than do researchers of wild animals.
In the evolutionary study of human personality, we foresee the growth
of three particularly exciting research areas. First, measurement of personality variation and its association with fitness (or putatively fitness-linked
characteristics such as growth rate or age at marriage) in a variety of
small-scale, nonliterate societies will explore (i) the flexibility of personality
structure itself and (ii) the ways that variable social, subsistence, and
pathogen-prevalence conditions can favor different patterns of personality
trait covariation. Multidimensional models, such as the FFM and the
six-factor HEXACO model (Ashton & Lee, 2007), might turn out to apply
only to the ultracomplex societies of recent history. Second, models of
state-dependent personality variation (e.g., facultative calibration) will
be tested in longitudinal and experimental studies that link changes in
perceived individual circumstances (e.g., availability of social support and
relative intelligence within a social milieu) to changes in personality traits
and personality-like states. Third, sophisticated genetic methods such as
genome-wide sequence analyses will continue to elucidate the genetic
architecture of personality traits, affording tests of contrasting predictions
from balancing selection and directional selection (e.g., mutation-selection
balance) models of personality variation.
Finally, we expect progress in innovative personality measurement
methods such as experimental implicit measures (e.g., attention to stimuli
indicative of social threats or opportunities), naturalistic observation using
techniques such as intermittent audio recording by portable devices (Mehl,
Gosling, & Pennebaker, 2006), and economic games with real money at
stake.
Cross-disciplinary collaboration and dialogue will be essential for further progress in the evolutionary study of personality (Nettle & Penke,
2010). Behavioral ecologists, both as theorists and as fieldworkers, are well
equipped to develop and test models linking (i) costs and benefits associated with various forms of environmental variation, (ii) within-individual
behavioral consistency and interindividual behavioral differences, and (iii)
lifetime inclusive fitness. Personality psychologists draw on a long tradition
of theoretical and statistical investigation of human personality structure,
that is, the covariance of trait dimensions suggested by folk descriptions

Evolutionary Perspectives on Animal and Human Personality

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and by neurophysiological mechanisms. Comparative psychologists deploy
ethological and experimental methods tailored to reveal reliable and valid
dimensions of personality in particular species. Behavioral economists’
methods engage individuals’ motives (e.g., prosociality and risk aversion)
in a controlled manner in the face of real costs and benefits. Neuroscientists’
findings regarding the proximate (anatomical and physiological) underpinnings of personality variation will need to be integrated with theoretical
accounts that focus on adaptive/functional explanations for personality
variation. Behavioral geneticists bring increasingly powerful techniques
capable of uncovering the signatures of past selection regimes.
Because these are early days in the evolutionary study of personality, we
can only speculate tentatively on its implications for practical applications.
We suspect that some personality configurations regarded by most contemporary Westerners as undesirable or even pathological (e.g., the highly conscientious, highly introverted person who is extremely reluctant to showcase
her impressive accomplishments) will come to be seen as understandable,
and perhaps best left alone, given an individual’s other characteristics and
social circumstances. Moreover, a wide range of personality variation, compared to pressure to adopt a particular configuration, may provide greater
benefit to society as a whole.
REFERENCES
Alvergne, A., Jokela, M., & Lummaa, V. (2010). Personality and reproductive success
in a high-fertility human population. Proceedings of the National Academy of Sciences
of the United States of America, 107, 11745–11750. doi:10.1073/pnas.1001752107
Ashton, M. C., & Lee, K. (2007). Empirical, theoretical, and practical advantages of the
HEXACO model of personality structure. Personality and Social Psychology Review,
11, 150–166. doi:10.1177/1088868306294907
Bailey, D. H., Walker, R. S., Blomquist, G. E., Hill, K. R., & Hurtado, A. M. (2013).
Heritability and fitness correlates of personality in the Ache, a natural-fertility
population in Paraguay. PLoS One, 8, e59325. doi:10.1371/journal.pone.0059325
Barnard, C. J., & Sibly, R. M. (1981). Producers and scroungers: A general model and
its application to captive flocks of house sparrows. Animal Behaviour, 29, 543–555.
doi:10.1016/S0003-3472(81)80117-0
Capitanio, J. P. (2011a). Individual differences in emotionality: Social temperament
and health. American Journal of Primatology, 73, 507–515. doi:10.1002/ajp.20870
Capitanio, J. P. (2011b). Nonhuman primate personality and immunity: Mechanisms
of health and disease. In A. Weiss, J. E. King & L. Murray (Eds.), Personality and
temperament in nonhuman primates (pp. 233–255). New York, NY: Springer.
Caspi, A., & Moffitt, T. E. (2006). Gene-environment interactions in psychiatry: joining forces with neuroscience. Nature Reviews Neuroscience, 7, 583–590. doi:10.1038/
nrn1925

10

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Cole, E. F., & Quinn, J. L. (2012). Personality and problem-solving performance
explain competitive ability in the wild. Proceedings of the Royal Society of London.
Series B: Biological Sciences, 279, 1168–1175. doi:10.1098/rspb.2011.1539
Costa, P. T. J., & McCrae, R. R. (1995). Domains and facets: Hierarchical personality assessment using the revised NEO Personality Inventory. Journal of Personality
Assessment, 64, 21–50. doi:10.1207/s15327752jpa6401_2
Digman, J. M. (1990). Personality structure: Emergence of the five-factor model.
Annual Review of Psychology, 41, 417–440. doi:10.1146/annurev.ps.41.020190.002221
Dingemanse, N. J., Both, C., & Drent, P. J. (2004). Fitness consequences of avian personalities in a fluctuating environment. Proceedings of the Royal Society of London.
Series B: Biological Sciences, 271, 847–852. doi:10.1098/rspb.2004.2680
Dingemanse, N. J., Both, C., Drent, P. J., van Oers, K., & van Noordwijk, A. J. (2002).
Repeatability and heritability of exploratory behaviour in great tits from the wild.
Animal Behaviour, 64, 929–938. doi:10.1006/anbe.2002.2006
Dingemanse, N. J., Kazem, A. J. N., Réale, D., & Wright, J. (2010). Behavioural reaction norms: Animal personality meets individual plasticity. Trends in Ecology and
Evolution, 25, 81–89. doi:10.1016/j.tree.2009.07.013
Eaves, L. J., Martin, N. G., Heath, A. C., Hewitt, J. K., & Neale, M. C. (1990).
Personality and reproductive fitness. Behavior Genetics, 20, 563–568. doi:10.1007/
BF01065872
Fairbanks, L. A., Jorgensen, M. J., Huff, A., Blau, K., Hung, Y.-Y., & Mann, J. J. (2004).
Adolescent impulsivity predicts adult dominance attainment in male vervet monkeys. American Journal of Primatology, 64, 1–17. doi:10.1002/ajp.20057
Figueredo, A. J., Vásquez, G., Brumbach, B. H., Sefcek, J. A., Kirsner, B. R., & Jacobs,
W. J. (2005). The K-factor: Individual differences in life history strategy. Personality
and Individual Differences, 39, 1349–1360. doi:10.1016/j.paid.2005.06.009
Freeman, H. D., & Gosling, S. D. (2010). Personality in nonhuman primates: A review
and evaluation of past research. American Journal of Primatology, 72, 653–671.
doi:10.1002/ajp.20833
Gosling, S. D., & John, O. P. (1999). Personality dimensions in nonhuman animals:
A cross-species review. Current Directions in Psychological Science, 8, 69–75.
Gurven, M., von Rueden, C., Massenkoff, M., & Kaplan, H. (2013). How universal
is the Big Five? Testing the Five Factor Model of personality variation among
forager-farmers in the Bolivian Amazon. Journal of Personality and Social Psychology,
104, 354–370. doi:10.1037/a0030841
Gurven, M., von Rueden, C., Stieglitz, J., Kaplan, H., & Rodriguez, D. E. (in press).
The evolutionary fitness of personality traits in small-scale subsistence society.
Evolution and Human Behavior. doi:10.1016/j.evolhumbehav.2013.09.002
Howell, S., Westergaard, G., Hoos, B., Chavanne, T. J., Shoaf, S. E., Cleveland,
A., … Higley, J. D. (2007). Serotonergic influences on life-history outcomes in
free-ranging male rhesus macaques. American Journal of Primatology, 69, 851–865.
doi:10.1002/ajp.20369
Keller, M. C., & Miller, G. F. (2006). Resolving the paradox of common, harmful, heritable mental disorders: Which evolutionary genetic models work best? Behavioral
and Brain Sciences, 29, 385–452. doi:10.1017/S0140525X06229091

Evolutionary Perspectives on Animal and Human Personality

11

Levine, S. (2005). Developmental determinants of sensitivity and resistance to stress.
Psychoneuroendocrinology, 30, 939–946. doi:10.1016/j.psyneuen.2005.03.013
Lukaszewski, A. W., & Roney, J. R. (2011). The origins of extraversion: Joint effects of
facultative calibration and genetic polymorphism. Personality and Social Psychology
Bulletin, 37, 409–421. doi:10.1177/0146167210397209
Manson, J. H., & Perry, S. (2013). Personality structure, sex differences, and temporal
change and stability in wild white-faced capuchins (Cebus capucinus). Journal of
Comparative Psychology, 127, 299–311. doi:10.1037/a0031316
McNamara, J. M., Stephens, P. A., Dall, S. R. X., & Houston, A. I. (2008). Evolution of
trust and trustworthiness: Social awareness favours personality differences. Proceedings of the Royal Society of London. Series B: Biological Sciences, 276, 605–613.
doi:10.1098/rspb.2008.1182
Mehl, M. R., Gosling, S. D., & Pennebaker, J. W. (2006). Personality in its natural
habitat: Manifestations and implicit folk theories of personality in daily life. Journal
of Personality and Social Psychology, 90, 862–877. doi:10.1037/0022-3514.90.5.862
Miller, G. F. (2000). Sexual selection for indicators of intelligence. In G. Bock, J. Goode
& K. Webb (Eds.), The nature of intelligence. New York, NY: John Wiley & Sons, Inc.
Nettle, D. (2005). An evolutionary approach to the extraversion continuum. Evolution
and Human Behavior, 26, 363–373. doi:10.1016/j.evolhumbehav.2004.12.00
Nettle, D., & Penke, L. (2010). Personality: Bridging the literatures from human psychology and behavioural ecology. Philosophical Transactions of the Royal Society of
London. Series B: Biological Sciences, 365, 4043–4050. doi:10.1098/rstb.2010.0061
Réale, D., & Festa-Bianchet, M. (2003). Predator-induced natural selection on temperament in bighorn ewes. Animal Behaviour, 65, 463–470. doi:10.1006/anbe.2003.2100
Réale, D., Gallant, B. Y., Leblanc, M., & Festa-Bianchet, M. (2000). Consistency of temperament in bighorn ewes and correlates with behaviour and life history. Animal
Behaviour, 60, 589–597. doi:10.1006/anbe.2000.1530
Rushton, J. P., Bons, T. A., & Hur, Y.-M. (2008). The genetics and evolution of
the general factor of personality. Journal of Research in Personality, 42, 1173–1185.
doi:10.1016/j.jrp.2008.03.002
Sih, A., Bell, A. M., Johnson, J. C., & Ziemba, R. E. (2004). Behavioral syndromes: An
integrative overview. Quarterly Review of Biology, 79, 241–277. doi:10.1086/422893
Smith, B. R., & Blumstein, D. T. (2008). Fitness consequences of personality: A
meta-analysis. Behavioral Ecology, 19, 448–455. doi:10.1093/beheco/arm144
Soumi, S. J. (2011). Risk, resilience, and gene-environment interplay in primates. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 289–297.
Stearns, S. C. (1992). The evolution of life histories. Oxford, England: Oxford University
Press.
Stevenson-Hinde, J., & Zunz, M. (1978). Subjective assessment of individual rhesus
monkeys. Primates, 19, 473–482.
Tooby, J., & Cosmides, L. (1990). On the universality of human nature and the uniqueness of the individual: The role of genetics and adaptation. Journal of Personality,
58(1), 17–67. doi:10.1111/j.1467-6494.1990.tb00907.x

12

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Verweij, K. J. H., Yang, J., Lahti, J., Veijola, J., Hintsanen, M., Pulkki-Råback, L., …
Zietsch, B. P. (2012). Maintenance of genetic variation in human personality: Testing evolutionary models by estimating heritability due to common causal variants and investigating the effect of distant inbreeding. Evolution, 66, 3238–3251.
doi:10.1111/j.1558-5646.2012.01679.x
Wilson, D. S., Clark, A. B., Coleman, K., & Dearstyne, T. (1994). Shyness and boldness in humans and other animals. Trends in Ecology and Evolution, 9, 442–446.
doi:10.1016/0169-5347(94)90134-1
Wolf, M., Doorn, G. S., van Leimar, O., & Weissing, F. J. (2007). Life-history trade-offs
favour the evolution of animal personalities. Nature, 447, 581–584. doi:10.1038/
nature05835

JOSEPH H. MANSON SHORT BIOGRAPHY
Joseph H. Manson (http://www.sscnet.ucla.edu/anthro/faculty/jmanson/
Home.html) is a Professor of Anthropology at the University of California,
Los Angeles. He has published studies of female mate choice in free-ranging
rhesus macaques and numerous topics, including personality structure,
in wild white-faced capuchin monkeys. More recently, he has studied the
interplay between a human personality trait, psychopathy, and face-to-face
interaction and economic game-play decisions in small groups of previously
unacquainted people. His current research uses audio sampling of individuals’ daily lives to test hypotheses about personality variation drawn from
life history theory.
LYNN A. FAIRBANKS SHORT BIOGRAPHY
Lynn A. Fairbanks (http://www.bec.ucla.edu/faculty.php?id=34) is an
Emeritus Professor of Psychiatry and Biobehavioral Sciences at the University of California, Los Angeles. She has published numerous articles on
individual differences in temperament and personality of vervet monkeys,
focusing on the contributions of genetic, maternal, and contextual influences
on variation in novelty seeking, impulsivity, sociability, and response
to stressful life events. Her research on variation in maternal behavior
illustrates the tradeoffs between maternal diet and condition, maternal
investment, and offspring response and resilience in the development
of behavioral differences. The eight-generation extended pedigree of the
Vervet Research Colony has allowed identification of genetic influences and
effects of gene–environment interactions on behavioral and physiological
traits.

Evolutionary Perspectives on Animal and Human Personality

13

RELATED ESSAYS
Kin-Directed Behavior in Primates (Anthropology), Carol M. Berman
Evolutionary Approaches to Understanding Children’s Academic Achievement (Psychology), David C. Geary and Daniel B. Berch
Genetics and Social Behavior (Anthropology), Henry Harpending and Gregory Cochran
An Evolutionary Perspective on Developmental Plasticity (Psychology),
Sarah Hartman and Jay Belsky
Grandmothers and the Evolution of Human Sociality (Anthropology), Kristen
Hawkes and James Coxworth
Childhood (Anthropology), Karen L. Kramer
Cooperative Breeding and Human Evolution (Anthropology), Karen L.
Kramer
Mechanisms of Fear Reducation (Psychology), Cynthia L. Lancaster and
Marie-H. Monfils
A Bio-Social-Cultural Approach to Early Cognitive Development: Entering
the Community of Minds (Psychology), Katherine Nelson
Gestural Communication in Nonhuman Species (Anthropology), Simone Pika
Vocal Communication in Primates (Anthropology), Katie E. Slocombe
Primate Allomaternal Care (Anthropology), Stacey Tecot and Andrea Baden



Evolutionary Perspectives on Animal
and Human Personality
JOSEPH H. MANSON and LYNN A. FAIRBANKS

Abstract
Among many nonhuman animals, individuals differ consistently in their response
tendencies (e.g., shy vs bold) across multiple contexts. Researchers have tested
evolutionary hypotheses accounting for these phenomena, and have also begun
exploring evolutionary explanations for human personality variation. For evolutionary biologists, a trait’s significance lies in its effects on fitness, that is, the lifetime
reproductive success of individuals who bear the trait, including indirect effects
through the reproductive success of genetic relatives. Recent evolutionary personality research has pursued several alternative theoretical lines of inquiry: balancing
selection models explore whether optimal levels of personality traits vary across time,
space, or trait frequency distribution; mutation-selection balance models propose that
selection for a single optimum personality configuration is undermined by mutations at multiple genetic loci; and facultative calibration models hold that personality
trait levels are adjusted, during individual development, to other characteristics
that affect social bargaining power. A promising general approach links personality
variation to variation in life history strategy, that is, the allocation of effort among the
competing demands of growth, somatic maintenance, mate acquisition, and parental
investment. Emerging areas of research include relationships between personality
variation and biological fitness in humans and other primates; the extent to which
personality trait levels are adjusted based on individual condition; the degree
to which situational flexibility varies among individuals; and whether proposed
structural models of personality, such as the human five-factor model (extraversion,
neuroticism, agreeableness, conscientiousness, and openness to experience) are
species-typical or are affected by variable ecological and social conditions.

INTRODUCTION
Traditional evolutionary approaches to animal behavior focused on optimal
responses (within developmental and contextual constraints) to adaptive
challenges such as predator encounters and contests over mates. Different
responses by different individuals of the same age, sex, and circumstances
were attributed to measurement error or to statistical “noise.” In the
past 15–20 years, inspired by pioneers such as Joan Stevenson-Hinde
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.

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(Stevenson-Hinde & Zunz, 1978), D.S. Wilson (Wilson, Clark, Coleman, &
Dearstyne, 1994), and Samuel Gosling (Gosling & John, 1999), researchers
have confirmed and extended the intuitions of pet owners and zookeepers
that (i) individual animals’ responses are, to a substantial extent, consistent
across situations and over long periods of time and (ii) individuals differ
in these response tendencies. These two features (within-individual consistency and between-individual differences) serve as the defining features
of personality for researchers of animal behavior. A closely related concept
developed by Andrew Sih (Sih, Bell, Johnson, & Ziemba, 2004), the behavioral
syndrome, emphasizes within-individual consistency across contexts—for
example, an individual may show above-average aggressiveness toward
predators, same-sexed rivals, and prospective mates.
The widespread observation of animal personality poses two theoretical
puzzles. First, why has not natural selection equipped animals to respond in
the fashion best suited to the present situation, rather than being constrained
by a consistent response style that may lead to suboptimal choices? Second,
given that some personality variation is a product of genetic variation among
individuals, how does natural selection maintain this variation? In general,
selection is expected to eliminate variation in traits relevant to biological fitness, that is, traits that affect an individual’s ability to survive, reproduce,
and pass its genes on to future generations. Inclusive fitness includes an individual’s own reproduction as well as its effects on its relatives’ reproduction,
devalued by the proportion of genes shared with that relative. Research into
the puzzles posed by animal personality has proceeded in parallel with a
small but growing body of evolutionarily based research on human personality variation.
FOUNDATIONAL RESEARCH
METHODS IN THE STUDY OF ANIMAL PERSONALITY
Two general methods have dominated research on nonhuman animal personality. Standardized tests expose animals to a situation designed to elicit
variable responses. For example, temporarily captive songbirds are videotaped in a room containing artificial trees, and observers record how many
trees are visited by each individual (Dingemanse, Both, Drent, van Oers, &
van Noordwijk, 2002). Bighorn sheep are scored as more bold if they are
more willing to enter a corral trap baited with salt, and as more docile if
they struggle less during handling by humans (Réale, Gallant, Leblanc, &
Festa-Bianchet, 2000). Novel objects or conspecifics may be placed in captive
animals’ enclosures, and their reactions systematically coded.

Evolutionary Perspectives on Animal and Human Personality

3

The rating method uses questionnaires containing 20–60 adjectives (e.g.,
active, popular, and irritable) on which experienced observers (e.g., zookeepers and field assistants) rate each animal on a multipoint scale. Statistical
techniques assess inter-rater reliability, and reduce the set of adjectives to a
smaller number of general factors or dimensions of variation (Freeman &
Gosling, 2010).
PROXIMATE AND DEVELOPMENTAL STUDIES
OF ANIMAL PERSONALITY
A large body of research has used animal models of human psychiatric and
behavioral disorders to focus on the proximate (e.g., physiological) and
developmental mechanisms underlying personality variation. For example,
adverse early experience, particularly separation from the mother, has been
linked to emotional dysregulation and anxiety-related traits in nonhuman
mammals (Levine, 2005). Genetic polymorphisms in neurochemical pathways have been shown to increase risk for antisocial behavior in humans
and nonhuman animals, and these “risk” genes interact with adverse
environments to increase vulnerability for behavioral disorders (Caspi &
Moffitt, 2006; Soumi, 2011). Individual differences in personality traits have
also been related to immune function and infectious disease susceptibility
(Capitanio, 2011a). These and other studies provide valuable information
about the proximate factors involved in personality variation, but they do
not explain how “risk” genes for fitness-reducing personality traits persist
in populations. For this, we turn to models from population biology.
PERSONALITY AND BIOLOGICAL FITNESS: FOUNDATIONAL STUDIES
Several different ideas have been proposed to explain how personality variation can be maintained in populations. Some researchers, beginning with
Wilson et al. (1994) have drawn hypotheses from the concepts of balancing
selection and trade-offs. The optimal level of a trait may vary geographically,
between generations, over an individual’s lifespan, between the sexes, or
as a function of the existing distribution of trait levels in a population.
As an example of the last phenomenon, frequency-dependent selection, if an
animal population contains a mix of foragers (who harvest food from the
environment) and scroungers (who parasitize the efforts of foragers), then
scroungers are likely to have a higher net energy intake than foragers when
scroungers are rare, but not when they are common (Barnard & Sibly, 1981).
Dingemanse, Both, and Drent (2004) have found that a songbird, the
great tit, shows considerable variation in the speed with which individuals
explore a novel environment. Fast explorers are also more risk-prone than

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

slow explorers. A multiyear study in the wild showed that during years of
food abundance and resultant high survival rates, fast-exploring adult males
and slow-exploring adult females survived at the highest rates, whereas
during years of scarcity, slow-exploring adult males and fast-exploring adult
females prevailed. Researchers attributed the results to the sex-differentiated
effects of resource availability on the intensity of within-sex competition. In
both sexes, fast-exploring individuals outcompeted slow-exploring individuals for access to winter food. Only males defend territories, and male–male
competition for these territories was greatest when many males survived
a bountiful winter. Females were subordinate to males in competition for
food, and were therefore at greater risk of death during winters of scarcity.
Similarly, complex relationships between personality and biological success have been found or suggested for other species. Réale and colleagues
(Réale & Festa-Bianchet, 2003; Réale et al., 2000) have shown that bolder wild
female bighorn sheep had higher fitness than shy females, and more docile
females had higher fitness than less docile females. However, boldness
and docility were negatively correlated, preventing natural selection from
shaping an optimal level of both personality traits. Among male rhesus
monkeys (Howell et al., 2007) and vervet monkeys (Fairbanks et al., 2004),
more impulsive, risk-prone individuals are at greater risk of injury before
reaching adulthood, but those who survive attain higher dominance rank
following transfer to a new social group in late adolescence. This pattern
suggests a trade-off between a higher risk of early death and a larger
reproductive payoff for survivors later in life. A meta-analysis of data from
10 mammal species and 2 fish species revealed that bolder individuals,
particularly males, experienced greater reproductive success but diminished
survival prospects (Smith & Blumstein, 2008).
Researchers of human personality have proposed possible fitness trade-offs
associated with personality variation, but relevant empirical studies remain
rare. The most widely accepted, although still controversial, structural
model of human personality posits five independently varying dimensions
(five-factor model or FFM) (Costa & McCrae, 1995; Digman, 1990): extraversion (gregariousness, activity, positive emotions); neuroticism (negative
affect, e.g., anxiety, anger, and depression) or its inverse emotional stability;
agreeableness (altruism, trust, and straightforwardness); conscientiousness
(order, self-discipline, and achievement striving) and openness to experience
(including openness to ideas, feelings, aesthetics). Nettle (2005) found that
among British adults, self-reported Extraversion was positively correlated
with number of sexual partners, but also with the probability of experiencing
hospitalization for accident or illness, suggesting a personality-mediated
trade-off (at least in ancestral human environments) between production
of offspring and individual survival. Relationships of human personality

Evolutionary Perspectives on Animal and Human Personality

5

variation to fitness might encompass interactions among traits, as in some
of the nonhuman animal systems. Among Australian women, the largest
completed family sizes were found among those who were either high in
extraversion and low in neuroticism or else low in extraversion and high in
neuroticism (Eaves, Martin, Heath, Hewitt, & Neale, 1990).
CUTTING-EDGE RESEARCH
Evolutionary personality theory has recently begun to catch up with the
rapid proliferation of empirical research. Several theorists have built on the
basic idea that personality variation is tied to variation in life history strategy,
that is, the allocation of effort among the competing demands of growth,
somatic maintenance, mate acquisition and parental investment (Stearns,
1992). For example, Wolf et al. (2007) have developed an evolutionary
model in which individuals may explore their environment thoroughly,
trading off some near-term reproduction for longer-term increased access
to higher-quality resources, or explore superficially, maximizing near-term
reproduction at the expense of future resource gains. Over a wide range of
starting conditions, a mix of stable personality configurations emerges, in
which thorough environmental exploration is linked with risk aversion in
both anti-predator and intraspecific aggressive contexts.
As an alternative to hypotheses that invoke balancing selection and
trade-offs to propose that a wide range of personality types is adaptive, some researchers have attributed human personality variation to
mutation-selection balance. In this view, natural selection favors a particular
human personality configuration, to which a large number of genetic loci
contribute, while mutations undermine this configuration. First developed
by Miller to explain persistent variation in intelligence (Miller, 2000) and
heritable mental illnesses (Keller & Miller, 2006), the mutation-selection
balance theory has been more controversially applied to normal personality
variation by Rushton, Bons, and Hur (2008). The hypothesized general factor
of personality (GFP) is based on a proposed positive correlation among
extraversion, agreeableness, conscientiousness, openness, and emotional
stability. Figueredo et al. (2005) argue that behavioral propensities function
best as coordinated sets of traits, and propose that people pursuing a slower
life history (late onset of reproductive activity, high investment in a small
number of children, etc.) are higher on the GFP. Another evolutionary
approach, proposed originally by Tooby and Cosmides (1990) and developed further more recently by Lukaszewski and Roney (2011), proposes
that human personality variation (e.g., in extraversion) is calibrated during
development to individual characteristics (e.g., physical attractiveness and
formidability) that affect social bargaining power.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Empirically, a recent study found that much of the heritable variation in
traits resembling extraversion and emotional stability reflects the combined
effects of many different low-frequency gene variants, as predicted by the
mutation-selection balance hypothesis (Verweij et al., 2012). On the other
hand, a study of traditional Senegalese villages found evidence for trade-offs
and stabilizing selection in women’s emotional stability: less stable women
produced more children, but more stable women’s children were healthier (Alvergne, Jokela, & Lummaa, 2010). The first large-scale published
research on personality variation in a small-scale (hunter-horticulturalist)
society (Gurven, von Rueden, Massenkoff, & Kaplan, 2013) found that a
two-factor model (prosociality and industriousness) produced the best fit
to the data, casting doubt on the universality of the FFM. Among men,
reproductive success was positively correlated with Industriousness and
with the FFM extraversion, conscientiousness, openness, and emotional
stability dimensions, whereas among women, relationships between
personality dimensions and fitness varied geographically (Gurven, von
Rueden, Stieglitz, Kaplan, & Rodriguez, in press). Among the Senegalese
studied by Alvergne et al. (2010) and among the recently settled former
hunting-gathering Ache of eastern Paraguay (Bailey, Walker, Blomquist,
Hill, & Hurtado, 2013), more extraverted men had higher reproductive
success.
Recent studies of nonhuman animals have explored dimensions of personality variation beyond the boldness and aggressiveness continua that
dominated earlier research. Among male great tits, competitive ability is
negatively correlated with innovative problem-solving ability (analogous to
human conscientiousness and/or openness) (Cole & Quinn, 2012). A model
of the evolution of trust and trustworthiness suggests that social awareness (i.e., monitoring of third party interactions) and within-individual
consistency in trustworthiness (a component of human Agreeableness)
can coevolve, each trait selecting for increases in the other (McNamara,
Stephens, Dall, & Houston, 2008).
KEY ISSUES FOR FUTURE RESEARCH
A number of key questions remain unresolved and will dominate evolutionary research into personality (both human and nonhuman) in the coming
years:
1. To what extent is personality variation associated with variation in
fitness? Models of balancing selection propose that, at least over wide
spatial and/or temporal scales, different levels of personality traits
have equal fitness. Alternatively, personality trait levels are expected to

Evolutionary Perspectives on Animal and Human Personality

2.

3.

4.

5.

7

correlate consistently with fitness (e.g., in humans, higher neuroticism
with lower fitness) in models of mutation-selection balance or adaptively flexible personality in response to variable fitness-relevant states
such as body size or parasite infection. Some personality configurations
might represent a disadvantaged individual “making the best of a bad
job,” in which case low fitness is expected (although not as low as
would occur if an individual in poor condition adopted a personality
configuration appropriate to good condition).
A closely related question is the extent to which personality variation
is condition-dependent (i.e., state-dependent). An alternative to statedependent models regards personality variation as driven largely by
variation in genotypes that affect psychological processes directly via
neural and/or hormonal machinery (e.g., androgen receptors).
What are the relative impacts on personality variation of early developmental events that may cue life prospects (e.g., maternal condition
during gestation and father absence during human childhood) versus
adult health, social status, threats, and opportunities?
What is the relationship between variation in dimensions such as
shy-bold, on the one hand, and individual variation in cross-situational
plasticity (e.g., the capacity to vary one’s level of boldness as a function
of context)? A promising, recently developed model by Dingemanse,
Kazem, Réale, and Wright (2010) integrates both forms of variation
using the concept of behavioral reaction norms. Among other advantages,
this concept facilitates the investigation of individual × environment
interaction, that is, the nonrandom distribution of personality types
across habitats.
How and why do different dimensions of personality variation covary
in different species and in different human populations?

Pursuing these research questions in nonhuman animals will entail
overcoming some formidable practical obstacles. Measuring lifetime fitness,
as well as its components (time to sexual maturity, age-specific survival
and fertility rates, offspring survival rates, etc.) in varied environments in
long-lived nonhuman animals in the wild is a slow and expensive endeavor.
However, personality measurement in wild populations promises to become
easier through the use of (i) standardized situational tests on temporarily
captive individuals and (ii) observer rating methods based on naturally
occurring behavior. The latter have demonstrated sufficient reliability and
validity in captive settings (e.g., Capitanio, 2011b) to justify their use in wild
populations (e.g., Manson & Perry, 2013), and such research will become
more common and fruitful. Some of the ecological variables (e.g., food

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

abundance, predation risk, and parasite prevalence) proposed by modelers to affect personality variation are measurable using well-established
methods, and new methods are currently being developed for noninvasive
measurement of metabolic and hormonal variables in large mammals in
the wild. Personality researchers studying captive or semi-free-ranging
animals lack the opportunity to measure ecological variables or to collect
generalizable data on fitness variation, but they have easier access to certain
proxies for fitness (e.g., growth rates) than do researchers of wild animals.
In the evolutionary study of human personality, we foresee the growth
of three particularly exciting research areas. First, measurement of personality variation and its association with fitness (or putatively fitness-linked
characteristics such as growth rate or age at marriage) in a variety of
small-scale, nonliterate societies will explore (i) the flexibility of personality
structure itself and (ii) the ways that variable social, subsistence, and
pathogen-prevalence conditions can favor different patterns of personality
trait covariation. Multidimensional models, such as the FFM and the
six-factor HEXACO model (Ashton & Lee, 2007), might turn out to apply
only to the ultracomplex societies of recent history. Second, models of
state-dependent personality variation (e.g., facultative calibration) will
be tested in longitudinal and experimental studies that link changes in
perceived individual circumstances (e.g., availability of social support and
relative intelligence within a social milieu) to changes in personality traits
and personality-like states. Third, sophisticated genetic methods such as
genome-wide sequence analyses will continue to elucidate the genetic
architecture of personality traits, affording tests of contrasting predictions
from balancing selection and directional selection (e.g., mutation-selection
balance) models of personality variation.
Finally, we expect progress in innovative personality measurement
methods such as experimental implicit measures (e.g., attention to stimuli
indicative of social threats or opportunities), naturalistic observation using
techniques such as intermittent audio recording by portable devices (Mehl,
Gosling, & Pennebaker, 2006), and economic games with real money at
stake.
Cross-disciplinary collaboration and dialogue will be essential for further progress in the evolutionary study of personality (Nettle & Penke,
2010). Behavioral ecologists, both as theorists and as fieldworkers, are well
equipped to develop and test models linking (i) costs and benefits associated with various forms of environmental variation, (ii) within-individual
behavioral consistency and interindividual behavioral differences, and (iii)
lifetime inclusive fitness. Personality psychologists draw on a long tradition
of theoretical and statistical investigation of human personality structure,
that is, the covariance of trait dimensions suggested by folk descriptions

Evolutionary Perspectives on Animal and Human Personality

9

and by neurophysiological mechanisms. Comparative psychologists deploy
ethological and experimental methods tailored to reveal reliable and valid
dimensions of personality in particular species. Behavioral economists’
methods engage individuals’ motives (e.g., prosociality and risk aversion)
in a controlled manner in the face of real costs and benefits. Neuroscientists’
findings regarding the proximate (anatomical and physiological) underpinnings of personality variation will need to be integrated with theoretical
accounts that focus on adaptive/functional explanations for personality
variation. Behavioral geneticists bring increasingly powerful techniques
capable of uncovering the signatures of past selection regimes.
Because these are early days in the evolutionary study of personality, we
can only speculate tentatively on its implications for practical applications.
We suspect that some personality configurations regarded by most contemporary Westerners as undesirable or even pathological (e.g., the highly conscientious, highly introverted person who is extremely reluctant to showcase
her impressive accomplishments) will come to be seen as understandable,
and perhaps best left alone, given an individual’s other characteristics and
social circumstances. Moreover, a wide range of personality variation, compared to pressure to adopt a particular configuration, may provide greater
benefit to society as a whole.
REFERENCES
Alvergne, A., Jokela, M., & Lummaa, V. (2010). Personality and reproductive success
in a high-fertility human population. Proceedings of the National Academy of Sciences
of the United States of America, 107, 11745–11750. doi:10.1073/pnas.1001752107
Ashton, M. C., & Lee, K. (2007). Empirical, theoretical, and practical advantages of the
HEXACO model of personality structure. Personality and Social Psychology Review,
11, 150–166. doi:10.1177/1088868306294907
Bailey, D. H., Walker, R. S., Blomquist, G. E., Hill, K. R., & Hurtado, A. M. (2013).
Heritability and fitness correlates of personality in the Ache, a natural-fertility
population in Paraguay. PLoS One, 8, e59325. doi:10.1371/journal.pone.0059325
Barnard, C. J., & Sibly, R. M. (1981). Producers and scroungers: A general model and
its application to captive flocks of house sparrows. Animal Behaviour, 29, 543–555.
doi:10.1016/S0003-3472(81)80117-0
Capitanio, J. P. (2011a). Individual differences in emotionality: Social temperament
and health. American Journal of Primatology, 73, 507–515. doi:10.1002/ajp.20870
Capitanio, J. P. (2011b). Nonhuman primate personality and immunity: Mechanisms
of health and disease. In A. Weiss, J. E. King & L. Murray (Eds.), Personality and
temperament in nonhuman primates (pp. 233–255). New York, NY: Springer.
Caspi, A., & Moffitt, T. E. (2006). Gene-environment interactions in psychiatry: joining forces with neuroscience. Nature Reviews Neuroscience, 7, 583–590. doi:10.1038/
nrn1925

10

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Cole, E. F., & Quinn, J. L. (2012). Personality and problem-solving performance
explain competitive ability in the wild. Proceedings of the Royal Society of London.
Series B: Biological Sciences, 279, 1168–1175. doi:10.1098/rspb.2011.1539
Costa, P. T. J., & McCrae, R. R. (1995). Domains and facets: Hierarchical personality assessment using the revised NEO Personality Inventory. Journal of Personality
Assessment, 64, 21–50. doi:10.1207/s15327752jpa6401_2
Digman, J. M. (1990). Personality structure: Emergence of the five-factor model.
Annual Review of Psychology, 41, 417–440. doi:10.1146/annurev.ps.41.020190.002221
Dingemanse, N. J., Both, C., & Drent, P. J. (2004). Fitness consequences of avian personalities in a fluctuating environment. Proceedings of the Royal Society of London.
Series B: Biological Sciences, 271, 847–852. doi:10.1098/rspb.2004.2680
Dingemanse, N. J., Both, C., Drent, P. J., van Oers, K., & van Noordwijk, A. J. (2002).
Repeatability and heritability of exploratory behaviour in great tits from the wild.
Animal Behaviour, 64, 929–938. doi:10.1006/anbe.2002.2006
Dingemanse, N. J., Kazem, A. J. N., Réale, D., & Wright, J. (2010). Behavioural reaction norms: Animal personality meets individual plasticity. Trends in Ecology and
Evolution, 25, 81–89. doi:10.1016/j.tree.2009.07.013
Eaves, L. J., Martin, N. G., Heath, A. C., Hewitt, J. K., & Neale, M. C. (1990).
Personality and reproductive fitness. Behavior Genetics, 20, 563–568. doi:10.1007/
BF01065872
Fairbanks, L. A., Jorgensen, M. J., Huff, A., Blau, K., Hung, Y.-Y., & Mann, J. J. (2004).
Adolescent impulsivity predicts adult dominance attainment in male vervet monkeys. American Journal of Primatology, 64, 1–17. doi:10.1002/ajp.20057
Figueredo, A. J., Vásquez, G., Brumbach, B. H., Sefcek, J. A., Kirsner, B. R., & Jacobs,
W. J. (2005). The K-factor: Individual differences in life history strategy. Personality
and Individual Differences, 39, 1349–1360. doi:10.1016/j.paid.2005.06.009
Freeman, H. D., & Gosling, S. D. (2010). Personality in nonhuman primates: A review
and evaluation of past research. American Journal of Primatology, 72, 653–671.
doi:10.1002/ajp.20833
Gosling, S. D., & John, O. P. (1999). Personality dimensions in nonhuman animals:
A cross-species review. Current Directions in Psychological Science, 8, 69–75.
Gurven, M., von Rueden, C., Massenkoff, M., & Kaplan, H. (2013). How universal
is the Big Five? Testing the Five Factor Model of personality variation among
forager-farmers in the Bolivian Amazon. Journal of Personality and Social Psychology,
104, 354–370. doi:10.1037/a0030841
Gurven, M., von Rueden, C., Stieglitz, J., Kaplan, H., & Rodriguez, D. E. (in press).
The evolutionary fitness of personality traits in small-scale subsistence society.
Evolution and Human Behavior. doi:10.1016/j.evolhumbehav.2013.09.002
Howell, S., Westergaard, G., Hoos, B., Chavanne, T. J., Shoaf, S. E., Cleveland,
A., … Higley, J. D. (2007). Serotonergic influences on life-history outcomes in
free-ranging male rhesus macaques. American Journal of Primatology, 69, 851–865.
doi:10.1002/ajp.20369
Keller, M. C., & Miller, G. F. (2006). Resolving the paradox of common, harmful, heritable mental disorders: Which evolutionary genetic models work best? Behavioral
and Brain Sciences, 29, 385–452. doi:10.1017/S0140525X06229091

Evolutionary Perspectives on Animal and Human Personality

11

Levine, S. (2005). Developmental determinants of sensitivity and resistance to stress.
Psychoneuroendocrinology, 30, 939–946. doi:10.1016/j.psyneuen.2005.03.013
Lukaszewski, A. W., & Roney, J. R. (2011). The origins of extraversion: Joint effects of
facultative calibration and genetic polymorphism. Personality and Social Psychology
Bulletin, 37, 409–421. doi:10.1177/0146167210397209
Manson, J. H., & Perry, S. (2013). Personality structure, sex differences, and temporal
change and stability in wild white-faced capuchins (Cebus capucinus). Journal of
Comparative Psychology, 127, 299–311. doi:10.1037/a0031316
McNamara, J. M., Stephens, P. A., Dall, S. R. X., & Houston, A. I. (2008). Evolution of
trust and trustworthiness: Social awareness favours personality differences. Proceedings of the Royal Society of London. Series B: Biological Sciences, 276, 605–613.
doi:10.1098/rspb.2008.1182
Mehl, M. R., Gosling, S. D., & Pennebaker, J. W. (2006). Personality in its natural
habitat: Manifestations and implicit folk theories of personality in daily life. Journal
of Personality and Social Psychology, 90, 862–877. doi:10.1037/0022-3514.90.5.862
Miller, G. F. (2000). Sexual selection for indicators of intelligence. In G. Bock, J. Goode
& K. Webb (Eds.), The nature of intelligence. New York, NY: John Wiley & Sons, Inc.
Nettle, D. (2005). An evolutionary approach to the extraversion continuum. Evolution
and Human Behavior, 26, 363–373. doi:10.1016/j.evolhumbehav.2004.12.00
Nettle, D., & Penke, L. (2010). Personality: Bridging the literatures from human psychology and behavioural ecology. Philosophical Transactions of the Royal Society of
London. Series B: Biological Sciences, 365, 4043–4050. doi:10.1098/rstb.2010.0061
Réale, D., & Festa-Bianchet, M. (2003). Predator-induced natural selection on temperament in bighorn ewes. Animal Behaviour, 65, 463–470. doi:10.1006/anbe.2003.2100
Réale, D., Gallant, B. Y., Leblanc, M., & Festa-Bianchet, M. (2000). Consistency of temperament in bighorn ewes and correlates with behaviour and life history. Animal
Behaviour, 60, 589–597. doi:10.1006/anbe.2000.1530
Rushton, J. P., Bons, T. A., & Hur, Y.-M. (2008). The genetics and evolution of
the general factor of personality. Journal of Research in Personality, 42, 1173–1185.
doi:10.1016/j.jrp.2008.03.002
Sih, A., Bell, A. M., Johnson, J. C., & Ziemba, R. E. (2004). Behavioral syndromes: An
integrative overview. Quarterly Review of Biology, 79, 241–277. doi:10.1086/422893
Smith, B. R., & Blumstein, D. T. (2008). Fitness consequences of personality: A
meta-analysis. Behavioral Ecology, 19, 448–455. doi:10.1093/beheco/arm144
Soumi, S. J. (2011). Risk, resilience, and gene-environment interplay in primates. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 289–297.
Stearns, S. C. (1992). The evolution of life histories. Oxford, England: Oxford University
Press.
Stevenson-Hinde, J., & Zunz, M. (1978). Subjective assessment of individual rhesus
monkeys. Primates, 19, 473–482.
Tooby, J., & Cosmides, L. (1990). On the universality of human nature and the uniqueness of the individual: The role of genetics and adaptation. Journal of Personality,
58(1), 17–67. doi:10.1111/j.1467-6494.1990.tb00907.x

12

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Verweij, K. J. H., Yang, J., Lahti, J., Veijola, J., Hintsanen, M., Pulkki-Råback, L., …
Zietsch, B. P. (2012). Maintenance of genetic variation in human personality: Testing evolutionary models by estimating heritability due to common causal variants and investigating the effect of distant inbreeding. Evolution, 66, 3238–3251.
doi:10.1111/j.1558-5646.2012.01679.x
Wilson, D. S., Clark, A. B., Coleman, K., & Dearstyne, T. (1994). Shyness and boldness in humans and other animals. Trends in Ecology and Evolution, 9, 442–446.
doi:10.1016/0169-5347(94)90134-1
Wolf, M., Doorn, G. S., van Leimar, O., & Weissing, F. J. (2007). Life-history trade-offs
favour the evolution of animal personalities. Nature, 447, 581–584. doi:10.1038/
nature05835

JOSEPH H. MANSON SHORT BIOGRAPHY
Joseph H. Manson (http://www.sscnet.ucla.edu/anthro/faculty/jmanson/
Home.html) is a Professor of Anthropology at the University of California,
Los Angeles. He has published studies of female mate choice in free-ranging
rhesus macaques and numerous topics, including personality structure,
in wild white-faced capuchin monkeys. More recently, he has studied the
interplay between a human personality trait, psychopathy, and face-to-face
interaction and economic game-play decisions in small groups of previously
unacquainted people. His current research uses audio sampling of individuals’ daily lives to test hypotheses about personality variation drawn from
life history theory.
LYNN A. FAIRBANKS SHORT BIOGRAPHY
Lynn A. Fairbanks (http://www.bec.ucla.edu/faculty.php?id=34) is an
Emeritus Professor of Psychiatry and Biobehavioral Sciences at the University of California, Los Angeles. She has published numerous articles on
individual differences in temperament and personality of vervet monkeys,
focusing on the contributions of genetic, maternal, and contextual influences
on variation in novelty seeking, impulsivity, sociability, and response
to stressful life events. Her research on variation in maternal behavior
illustrates the tradeoffs between maternal diet and condition, maternal
investment, and offspring response and resilience in the development
of behavioral differences. The eight-generation extended pedigree of the
Vervet Research Colony has allowed identification of genetic influences and
effects of gene–environment interactions on behavioral and physiological
traits.

Evolutionary Perspectives on Animal and Human Personality

13

RELATED ESSAYS
Kin-Directed Behavior in Primates (Anthropology), Carol M. Berman
Evolutionary Approaches to Understanding Children’s Academic Achievement (Psychology), David C. Geary and Daniel B. Berch
Genetics and Social Behavior (Anthropology), Henry Harpending and Gregory Cochran
An Evolutionary Perspective on Developmental Plasticity (Psychology),
Sarah Hartman and Jay Belsky
Grandmothers and the Evolution of Human Sociality (Anthropology), Kristen
Hawkes and James Coxworth
Childhood (Anthropology), Karen L. Kramer
Cooperative Breeding and Human Evolution (Anthropology), Karen L.
Kramer
Mechanisms of Fear Reducation (Psychology), Cynthia L. Lancaster and
Marie-H. Monfils
A Bio-Social-Cultural Approach to Early Cognitive Development: Entering
the Community of Minds (Psychology), Katherine Nelson
Gestural Communication in Nonhuman Species (Anthropology), Simone Pika
Vocal Communication in Primates (Anthropology), Katie E. Slocombe
Primate Allomaternal Care (Anthropology), Stacey Tecot and Andrea Baden


Evolutionary Perspectives on Animal
and Human Personality
JOSEPH H. MANSON and LYNN A. FAIRBANKS

Abstract
Among many nonhuman animals, individuals differ consistently in their response
tendencies (e.g., shy vs bold) across multiple contexts. Researchers have tested
evolutionary hypotheses accounting for these phenomena, and have also begun
exploring evolutionary explanations for human personality variation. For evolutionary biologists, a trait’s significance lies in its effects on fitness, that is, the lifetime
reproductive success of individuals who bear the trait, including indirect effects
through the reproductive success of genetic relatives. Recent evolutionary personality research has pursued several alternative theoretical lines of inquiry: balancing
selection models explore whether optimal levels of personality traits vary across time,
space, or trait frequency distribution; mutation-selection balance models propose that
selection for a single optimum personality configuration is undermined by mutations at multiple genetic loci; and facultative calibration models hold that personality
trait levels are adjusted, during individual development, to other characteristics
that affect social bargaining power. A promising general approach links personality
variation to variation in life history strategy, that is, the allocation of effort among the
competing demands of growth, somatic maintenance, mate acquisition, and parental
investment. Emerging areas of research include relationships between personality
variation and biological fitness in humans and other primates; the extent to which
personality trait levels are adjusted based on individual condition; the degree
to which situational flexibility varies among individuals; and whether proposed
structural models of personality, such as the human five-factor model (extraversion,
neuroticism, agreeableness, conscientiousness, and openness to experience) are
species-typical or are affected by variable ecological and social conditions.

INTRODUCTION
Traditional evolutionary approaches to animal behavior focused on optimal
responses (within developmental and contextual constraints) to adaptive
challenges such as predator encounters and contests over mates. Different
responses by different individuals of the same age, sex, and circumstances
were attributed to measurement error or to statistical “noise.” In the
past 15–20 years, inspired by pioneers such as Joan Stevenson-Hinde
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.

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(Stevenson-Hinde & Zunz, 1978), D.S. Wilson (Wilson, Clark, Coleman, &
Dearstyne, 1994), and Samuel Gosling (Gosling & John, 1999), researchers
have confirmed and extended the intuitions of pet owners and zookeepers
that (i) individual animals’ responses are, to a substantial extent, consistent
across situations and over long periods of time and (ii) individuals differ
in these response tendencies. These two features (within-individual consistency and between-individual differences) serve as the defining features
of personality for researchers of animal behavior. A closely related concept
developed by Andrew Sih (Sih, Bell, Johnson, & Ziemba, 2004), the behavioral
syndrome, emphasizes within-individual consistency across contexts—for
example, an individual may show above-average aggressiveness toward
predators, same-sexed rivals, and prospective mates.
The widespread observation of animal personality poses two theoretical
puzzles. First, why has not natural selection equipped animals to respond in
the fashion best suited to the present situation, rather than being constrained
by a consistent response style that may lead to suboptimal choices? Second,
given that some personality variation is a product of genetic variation among
individuals, how does natural selection maintain this variation? In general,
selection is expected to eliminate variation in traits relevant to biological fitness, that is, traits that affect an individual’s ability to survive, reproduce,
and pass its genes on to future generations. Inclusive fitness includes an individual’s own reproduction as well as its effects on its relatives’ reproduction,
devalued by the proportion of genes shared with that relative. Research into
the puzzles posed by animal personality has proceeded in parallel with a
small but growing body of evolutionarily based research on human personality variation.
FOUNDATIONAL RESEARCH
METHODS IN THE STUDY OF ANIMAL PERSONALITY
Two general methods have dominated research on nonhuman animal personality. Standardized tests expose animals to a situation designed to elicit
variable responses. For example, temporarily captive songbirds are videotaped in a room containing artificial trees, and observers record how many
trees are visited by each individual (Dingemanse, Both, Drent, van Oers, &
van Noordwijk, 2002). Bighorn sheep are scored as more bold if they are
more willing to enter a corral trap baited with salt, and as more docile if
they struggle less during handling by humans (Réale, Gallant, Leblanc, &
Festa-Bianchet, 2000). Novel objects or conspecifics may be placed in captive
animals’ enclosures, and their reactions systematically coded.

Evolutionary Perspectives on Animal and Human Personality

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The rating method uses questionnaires containing 20–60 adjectives (e.g.,
active, popular, and irritable) on which experienced observers (e.g., zookeepers and field assistants) rate each animal on a multipoint scale. Statistical
techniques assess inter-rater reliability, and reduce the set of adjectives to a
smaller number of general factors or dimensions of variation (Freeman &
Gosling, 2010).
PROXIMATE AND DEVELOPMENTAL STUDIES
OF ANIMAL PERSONALITY
A large body of research has used animal models of human psychiatric and
behavioral disorders to focus on the proximate (e.g., physiological) and
developmental mechanisms underlying personality variation. For example,
adverse early experience, particularly separation from the mother, has been
linked to emotional dysregulation and anxiety-related traits in nonhuman
mammals (Levine, 2005). Genetic polymorphisms in neurochemical pathways have been shown to increase risk for antisocial behavior in humans
and nonhuman animals, and these “risk” genes interact with adverse
environments to increase vulnerability for behavioral disorders (Caspi &
Moffitt, 2006; Soumi, 2011). Individual differences in personality traits have
also been related to immune function and infectious disease susceptibility
(Capitanio, 2011a). These and other studies provide valuable information
about the proximate factors involved in personality variation, but they do
not explain how “risk” genes for fitness-reducing personality traits persist
in populations. For this, we turn to models from population biology.
PERSONALITY AND BIOLOGICAL FITNESS: FOUNDATIONAL STUDIES
Several different ideas have been proposed to explain how personality variation can be maintained in populations. Some researchers, beginning with
Wilson et al. (1994) have drawn hypotheses from the concepts of balancing
selection and trade-offs. The optimal level of a trait may vary geographically,
between generations, over an individual’s lifespan, between the sexes, or
as a function of the existing distribution of trait levels in a population.
As an example of the last phenomenon, frequency-dependent selection, if an
animal population contains a mix of foragers (who harvest food from the
environment) and scroungers (who parasitize the efforts of foragers), then
scroungers are likely to have a higher net energy intake than foragers when
scroungers are rare, but not when they are common (Barnard & Sibly, 1981).
Dingemanse, Both, and Drent (2004) have found that a songbird, the
great tit, shows considerable variation in the speed with which individuals
explore a novel environment. Fast explorers are also more risk-prone than

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

slow explorers. A multiyear study in the wild showed that during years of
food abundance and resultant high survival rates, fast-exploring adult males
and slow-exploring adult females survived at the highest rates, whereas
during years of scarcity, slow-exploring adult males and fast-exploring adult
females prevailed. Researchers attributed the results to the sex-differentiated
effects of resource availability on the intensity of within-sex competition. In
both sexes, fast-exploring individuals outcompeted slow-exploring individuals for access to winter food. Only males defend territories, and male–male
competition for these territories was greatest when many males survived
a bountiful winter. Females were subordinate to males in competition for
food, and were therefore at greater risk of death during winters of scarcity.
Similarly, complex relationships between personality and biological success have been found or suggested for other species. Réale and colleagues
(Réale & Festa-Bianchet, 2003; Réale et al., 2000) have shown that bolder wild
female bighorn sheep had higher fitness than shy females, and more docile
females had higher fitness than less docile females. However, boldness
and docility were negatively correlated, preventing natural selection from
shaping an optimal level of both personality traits. Among male rhesus
monkeys (Howell et al., 2007) and vervet monkeys (Fairbanks et al., 2004),
more impulsive, risk-prone individuals are at greater risk of injury before
reaching adulthood, but those who survive attain higher dominance rank
following transfer to a new social group in late adolescence. This pattern
suggests a trade-off between a higher risk of early death and a larger
reproductive payoff for survivors later in life. A meta-analysis of data from
10 mammal species and 2 fish species revealed that bolder individuals,
particularly males, experienced greater reproductive success but diminished
survival prospects (Smith & Blumstein, 2008).
Researchers of human personality have proposed possible fitness trade-offs
associated with personality variation, but relevant empirical studies remain
rare. The most widely accepted, although still controversial, structural
model of human personality posits five independently varying dimensions
(five-factor model or FFM) (Costa & McCrae, 1995; Digman, 1990): extraversion (gregariousness, activity, positive emotions); neuroticism (negative
affect, e.g., anxiety, anger, and depression) or its inverse emotional stability;
agreeableness (altruism, trust, and straightforwardness); conscientiousness
(order, self-discipline, and achievement striving) and openness to experience
(including openness to ideas, feelings, aesthetics). Nettle (2005) found that
among British adults, self-reported Extraversion was positively correlated
with number of sexual partners, but also with the probability of experiencing
hospitalization for accident or illness, suggesting a personality-mediated
trade-off (at least in ancestral human environments) between production
of offspring and individual survival. Relationships of human personality

Evolutionary Perspectives on Animal and Human Personality

5

variation to fitness might encompass interactions among traits, as in some
of the nonhuman animal systems. Among Australian women, the largest
completed family sizes were found among those who were either high in
extraversion and low in neuroticism or else low in extraversion and high in
neuroticism (Eaves, Martin, Heath, Hewitt, & Neale, 1990).
CUTTING-EDGE RESEARCH
Evolutionary personality theory has recently begun to catch up with the
rapid proliferation of empirical research. Several theorists have built on the
basic idea that personality variation is tied to variation in life history strategy,
that is, the allocation of effort among the competing demands of growth,
somatic maintenance, mate acquisition and parental investment (Stearns,
1992). For example, Wolf et al. (2007) have developed an evolutionary
model in which individuals may explore their environment thoroughly,
trading off some near-term reproduction for longer-term increased access
to higher-quality resources, or explore superficially, maximizing near-term
reproduction at the expense of future resource gains. Over a wide range of
starting conditions, a mix of stable personality configurations emerges, in
which thorough environmental exploration is linked with risk aversion in
both anti-predator and intraspecific aggressive contexts.
As an alternative to hypotheses that invoke balancing selection and
trade-offs to propose that a wide range of personality types is adaptive, some researchers have attributed human personality variation to
mutation-selection balance. In this view, natural selection favors a particular
human personality configuration, to which a large number of genetic loci
contribute, while mutations undermine this configuration. First developed
by Miller to explain persistent variation in intelligence (Miller, 2000) and
heritable mental illnesses (Keller & Miller, 2006), the mutation-selection
balance theory has been more controversially applied to normal personality
variation by Rushton, Bons, and Hur (2008). The hypothesized general factor
of personality (GFP) is based on a proposed positive correlation among
extraversion, agreeableness, conscientiousness, openness, and emotional
stability. Figueredo et al. (2005) argue that behavioral propensities function
best as coordinated sets of traits, and propose that people pursuing a slower
life history (late onset of reproductive activity, high investment in a small
number of children, etc.) are higher on the GFP. Another evolutionary
approach, proposed originally by Tooby and Cosmides (1990) and developed further more recently by Lukaszewski and Roney (2011), proposes
that human personality variation (e.g., in extraversion) is calibrated during
development to individual characteristics (e.g., physical attractiveness and
formidability) that affect social bargaining power.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Empirically, a recent study found that much of the heritable variation in
traits resembling extraversion and emotional stability reflects the combined
effects of many different low-frequency gene variants, as predicted by the
mutation-selection balance hypothesis (Verweij et al., 2012). On the other
hand, a study of traditional Senegalese villages found evidence for trade-offs
and stabilizing selection in women’s emotional stability: less stable women
produced more children, but more stable women’s children were healthier (Alvergne, Jokela, & Lummaa, 2010). The first large-scale published
research on personality variation in a small-scale (hunter-horticulturalist)
society (Gurven, von Rueden, Massenkoff, & Kaplan, 2013) found that a
two-factor model (prosociality and industriousness) produced the best fit
to the data, casting doubt on the universality of the FFM. Among men,
reproductive success was positively correlated with Industriousness and
with the FFM extraversion, conscientiousness, openness, and emotional
stability dimensions, whereas among women, relationships between
personality dimensions and fitness varied geographically (Gurven, von
Rueden, Stieglitz, Kaplan, & Rodriguez, in press). Among the Senegalese
studied by Alvergne et al. (2010) and among the recently settled former
hunting-gathering Ache of eastern Paraguay (Bailey, Walker, Blomquist,
Hill, & Hurtado, 2013), more extraverted men had higher reproductive
success.
Recent studies of nonhuman animals have explored dimensions of personality variation beyond the boldness and aggressiveness continua that
dominated earlier research. Among male great tits, competitive ability is
negatively correlated with innovative problem-solving ability (analogous to
human conscientiousness and/or openness) (Cole & Quinn, 2012). A model
of the evolution of trust and trustworthiness suggests that social awareness (i.e., monitoring of third party interactions) and within-individual
consistency in trustworthiness (a component of human Agreeableness)
can coevolve, each trait selecting for increases in the other (McNamara,
Stephens, Dall, & Houston, 2008).
KEY ISSUES FOR FUTURE RESEARCH
A number of key questions remain unresolved and will dominate evolutionary research into personality (both human and nonhuman) in the coming
years:
1. To what extent is personality variation associated with variation in
fitness? Models of balancing selection propose that, at least over wide
spatial and/or temporal scales, different levels of personality traits
have equal fitness. Alternatively, personality trait levels are expected to

Evolutionary Perspectives on Animal and Human Personality

2.

3.

4.

5.

7

correlate consistently with fitness (e.g., in humans, higher neuroticism
with lower fitness) in models of mutation-selection balance or adaptively flexible personality in response to variable fitness-relevant states
such as body size or parasite infection. Some personality configurations
might represent a disadvantaged individual “making the best of a bad
job,” in which case low fitness is expected (although not as low as
would occur if an individual in poor condition adopted a personality
configuration appropriate to good condition).
A closely related question is the extent to which personality variation
is condition-dependent (i.e., state-dependent). An alternative to statedependent models regards personality variation as driven largely by
variation in genotypes that affect psychological processes directly via
neural and/or hormonal machinery (e.g., androgen receptors).
What are the relative impacts on personality variation of early developmental events that may cue life prospects (e.g., maternal condition
during gestation and father absence during human childhood) versus
adult health, social status, threats, and opportunities?
What is the relationship between variation in dimensions such as
shy-bold, on the one hand, and individual variation in cross-situational
plasticity (e.g., the capacity to vary one’s level of boldness as a function
of context)? A promising, recently developed model by Dingemanse,
Kazem, Réale, and Wright (2010) integrates both forms of variation
using the concept of behavioral reaction norms. Among other advantages,
this concept facilitates the investigation of individual × environment
interaction, that is, the nonrandom distribution of personality types
across habitats.
How and why do different dimensions of personality variation covary
in different species and in different human populations?

Pursuing these research questions in nonhuman animals will entail
overcoming some formidable practical obstacles. Measuring lifetime fitness,
as well as its components (time to sexual maturity, age-specific survival
and fertility rates, offspring survival rates, etc.) in varied environments in
long-lived nonhuman animals in the wild is a slow and expensive endeavor.
However, personality measurement in wild populations promises to become
easier through the use of (i) standardized situational tests on temporarily
captive individuals and (ii) observer rating methods based on naturally
occurring behavior. The latter have demonstrated sufficient reliability and
validity in captive settings (e.g., Capitanio, 2011b) to justify their use in wild
populations (e.g., Manson & Perry, 2013), and such research will become
more common and fruitful. Some of the ecological variables (e.g., food

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

abundance, predation risk, and parasite prevalence) proposed by modelers to affect personality variation are measurable using well-established
methods, and new methods are currently being developed for noninvasive
measurement of metabolic and hormonal variables in large mammals in
the wild. Personality researchers studying captive or semi-free-ranging
animals lack the opportunity to measure ecological variables or to collect
generalizable data on fitness variation, but they have easier access to certain
proxies for fitness (e.g., growth rates) than do researchers of wild animals.
In the evolutionary study of human personality, we foresee the growth
of three particularly exciting research areas. First, measurement of personality variation and its association with fitness (or putatively fitness-linked
characteristics such as growth rate or age at marriage) in a variety of
small-scale, nonliterate societies will explore (i) the flexibility of personality
structure itself and (ii) the ways that variable social, subsistence, and
pathogen-prevalence conditions can favor different patterns of personality
trait covariation. Multidimensional models, such as the FFM and the
six-factor HEXACO model (Ashton & Lee, 2007), might turn out to apply
only to the ultracomplex societies of recent history. Second, models of
state-dependent personality variation (e.g., facultative calibration) will
be tested in longitudinal and experimental studies that link changes in
perceived individual circumstances (e.g., availability of social support and
relative intelligence within a social milieu) to changes in personality traits
and personality-like states. Third, sophisticated genetic methods such as
genome-wide sequence analyses will continue to elucidate the genetic
architecture of personality traits, affording tests of contrasting predictions
from balancing selection and directional selection (e.g., mutation-selection
balance) models of personality variation.
Finally, we expect progress in innovative personality measurement
methods such as experimental implicit measures (e.g., attention to stimuli
indicative of social threats or opportunities), naturalistic observation using
techniques such as intermittent audio recording by portable devices (Mehl,
Gosling, & Pennebaker, 2006), and economic games with real money at
stake.
Cross-disciplinary collaboration and dialogue will be essential for further progress in the evolutionary study of personality (Nettle & Penke,
2010). Behavioral ecologists, both as theorists and as fieldworkers, are well
equipped to develop and test models linking (i) costs and benefits associated with various forms of environmental variation, (ii) within-individual
behavioral consistency and interindividual behavioral differences, and (iii)
lifetime inclusive fitness. Personality psychologists draw on a long tradition
of theoretical and statistical investigation of human personality structure,
that is, the covariance of trait dimensions suggested by folk descriptions

Evolutionary Perspectives on Animal and Human Personality

9

and by neurophysiological mechanisms. Comparative psychologists deploy
ethological and experimental methods tailored to reveal reliable and valid
dimensions of personality in particular species. Behavioral economists’
methods engage individuals’ motives (e.g., prosociality and risk aversion)
in a controlled manner in the face of real costs and benefits. Neuroscientists’
findings regarding the proximate (anatomical and physiological) underpinnings of personality variation will need to be integrated with theoretical
accounts that focus on adaptive/functional explanations for personality
variation. Behavioral geneticists bring increasingly powerful techniques
capable of uncovering the signatures of past selection regimes.
Because these are early days in the evolutionary study of personality, we
can only speculate tentatively on its implications for practical applications.
We suspect that some personality configurations regarded by most contemporary Westerners as undesirable or even pathological (e.g., the highly conscientious, highly introverted person who is extremely reluctant to showcase
her impressive accomplishments) will come to be seen as understandable,
and perhaps best left alone, given an individual’s other characteristics and
social circumstances. Moreover, a wide range of personality variation, compared to pressure to adopt a particular configuration, may provide greater
benefit to society as a whole.
REFERENCES
Alvergne, A., Jokela, M., & Lummaa, V. (2010). Personality and reproductive success
in a high-fertility human population. Proceedings of the National Academy of Sciences
of the United States of America, 107, 11745–11750. doi:10.1073/pnas.1001752107
Ashton, M. C., & Lee, K. (2007). Empirical, theoretical, and practical advantages of the
HEXACO model of personality structure. Personality and Social Psychology Review,
11, 150–166. doi:10.1177/1088868306294907
Bailey, D. H., Walker, R. S., Blomquist, G. E., Hill, K. R., & Hurtado, A. M. (2013).
Heritability and fitness correlates of personality in the Ache, a natural-fertility
population in Paraguay. PLoS One, 8, e59325. doi:10.1371/journal.pone.0059325
Barnard, C. J., & Sibly, R. M. (1981). Producers and scroungers: A general model and
its application to captive flocks of house sparrows. Animal Behaviour, 29, 543–555.
doi:10.1016/S0003-3472(81)80117-0
Capitanio, J. P. (2011a). Individual differences in emotionality: Social temperament
and health. American Journal of Primatology, 73, 507–515. doi:10.1002/ajp.20870
Capitanio, J. P. (2011b). Nonhuman primate personality and immunity: Mechanisms
of health and disease. In A. Weiss, J. E. King & L. Murray (Eds.), Personality and
temperament in nonhuman primates (pp. 233–255). New York, NY: Springer.
Caspi, A., & Moffitt, T. E. (2006). Gene-environment interactions in psychiatry: joining forces with neuroscience. Nature Reviews Neuroscience, 7, 583–590. doi:10.1038/
nrn1925

10

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Cole, E. F., & Quinn, J. L. (2012). Personality and problem-solving performance
explain competitive ability in the wild. Proceedings of the Royal Society of London.
Series B: Biological Sciences, 279, 1168–1175. doi:10.1098/rspb.2011.1539
Costa, P. T. J., & McCrae, R. R. (1995). Domains and facets: Hierarchical personality assessment using the revised NEO Personality Inventory. Journal of Personality
Assessment, 64, 21–50. doi:10.1207/s15327752jpa6401_2
Digman, J. M. (1990). Personality structure: Emergence of the five-factor model.
Annual Review of Psychology, 41, 417–440. doi:10.1146/annurev.ps.41.020190.002221
Dingemanse, N. J., Both, C., & Drent, P. J. (2004). Fitness consequences of avian personalities in a fluctuating environment. Proceedings of the Royal Society of London.
Series B: Biological Sciences, 271, 847–852. doi:10.1098/rspb.2004.2680
Dingemanse, N. J., Both, C., Drent, P. J., van Oers, K., & van Noordwijk, A. J. (2002).
Repeatability and heritability of exploratory behaviour in great tits from the wild.
Animal Behaviour, 64, 929–938. doi:10.1006/anbe.2002.2006
Dingemanse, N. J., Kazem, A. J. N., Réale, D., & Wright, J. (2010). Behavioural reaction norms: Animal personality meets individual plasticity. Trends in Ecology and
Evolution, 25, 81–89. doi:10.1016/j.tree.2009.07.013
Eaves, L. J., Martin, N. G., Heath, A. C., Hewitt, J. K., & Neale, M. C. (1990).
Personality and reproductive fitness. Behavior Genetics, 20, 563–568. doi:10.1007/
BF01065872
Fairbanks, L. A., Jorgensen, M. J., Huff, A., Blau, K., Hung, Y.-Y., & Mann, J. J. (2004).
Adolescent impulsivity predicts adult dominance attainment in male vervet monkeys. American Journal of Primatology, 64, 1–17. doi:10.1002/ajp.20057
Figueredo, A. J., Vásquez, G., Brumbach, B. H., Sefcek, J. A., Kirsner, B. R., & Jacobs,
W. J. (2005). The K-factor: Individual differences in life history strategy. Personality
and Individual Differences, 39, 1349–1360. doi:10.1016/j.paid.2005.06.009
Freeman, H. D., & Gosling, S. D. (2010). Personality in nonhuman primates: A review
and evaluation of past research. American Journal of Primatology, 72, 653–671.
doi:10.1002/ajp.20833
Gosling, S. D., & John, O. P. (1999). Personality dimensions in nonhuman animals:
A cross-species review. Current Directions in Psychological Science, 8, 69–75.
Gurven, M., von Rueden, C., Massenkoff, M., & Kaplan, H. (2013). How universal
is the Big Five? Testing the Five Factor Model of personality variation among
forager-farmers in the Bolivian Amazon. Journal of Personality and Social Psychology,
104, 354–370. doi:10.1037/a0030841
Gurven, M., von Rueden, C., Stieglitz, J., Kaplan, H., & Rodriguez, D. E. (in press).
The evolutionary fitness of personality traits in small-scale subsistence society.
Evolution and Human Behavior. doi:10.1016/j.evolhumbehav.2013.09.002
Howell, S., Westergaard, G., Hoos, B., Chavanne, T. J., Shoaf, S. E., Cleveland,
A., … Higley, J. D. (2007). Serotonergic influences on life-history outcomes in
free-ranging male rhesus macaques. American Journal of Primatology, 69, 851–865.
doi:10.1002/ajp.20369
Keller, M. C., & Miller, G. F. (2006). Resolving the paradox of common, harmful, heritable mental disorders: Which evolutionary genetic models work best? Behavioral
and Brain Sciences, 29, 385–452. doi:10.1017/S0140525X06229091

Evolutionary Perspectives on Animal and Human Personality

11

Levine, S. (2005). Developmental determinants of sensitivity and resistance to stress.
Psychoneuroendocrinology, 30, 939–946. doi:10.1016/j.psyneuen.2005.03.013
Lukaszewski, A. W., & Roney, J. R. (2011). The origins of extraversion: Joint effects of
facultative calibration and genetic polymorphism. Personality and Social Psychology
Bulletin, 37, 409–421. doi:10.1177/0146167210397209
Manson, J. H., & Perry, S. (2013). Personality structure, sex differences, and temporal
change and stability in wild white-faced capuchins (Cebus capucinus). Journal of
Comparative Psychology, 127, 299–311. doi:10.1037/a0031316
McNamara, J. M., Stephens, P. A., Dall, S. R. X., & Houston, A. I. (2008). Evolution of
trust and trustworthiness: Social awareness favours personality differences. Proceedings of the Royal Society of London. Series B: Biological Sciences, 276, 605–613.
doi:10.1098/rspb.2008.1182
Mehl, M. R., Gosling, S. D., & Pennebaker, J. W. (2006). Personality in its natural
habitat: Manifestations and implicit folk theories of personality in daily life. Journal
of Personality and Social Psychology, 90, 862–877. doi:10.1037/0022-3514.90.5.862
Miller, G. F. (2000). Sexual selection for indicators of intelligence. In G. Bock, J. Goode
& K. Webb (Eds.), The nature of intelligence. New York, NY: John Wiley & Sons, Inc.
Nettle, D. (2005). An evolutionary approach to the extraversion continuum. Evolution
and Human Behavior, 26, 363–373. doi:10.1016/j.evolhumbehav.2004.12.00
Nettle, D., & Penke, L. (2010). Personality: Bridging the literatures from human psychology and behavioural ecology. Philosophical Transactions of the Royal Society of
London. Series B: Biological Sciences, 365, 4043–4050. doi:10.1098/rstb.2010.0061
Réale, D., & Festa-Bianchet, M. (2003). Predator-induced natural selection on temperament in bighorn ewes. Animal Behaviour, 65, 463–470. doi:10.1006/anbe.2003.2100
Réale, D., Gallant, B. Y., Leblanc, M., & Festa-Bianchet, M. (2000). Consistency of temperament in bighorn ewes and correlates with behaviour and life history. Animal
Behaviour, 60, 589–597. doi:10.1006/anbe.2000.1530
Rushton, J. P., Bons, T. A., & Hur, Y.-M. (2008). The genetics and evolution of
the general factor of personality. Journal of Research in Personality, 42, 1173–1185.
doi:10.1016/j.jrp.2008.03.002
Sih, A., Bell, A. M., Johnson, J. C., & Ziemba, R. E. (2004). Behavioral syndromes: An
integrative overview. Quarterly Review of Biology, 79, 241–277. doi:10.1086/422893
Smith, B. R., & Blumstein, D. T. (2008). Fitness consequences of personality: A
meta-analysis. Behavioral Ecology, 19, 448–455. doi:10.1093/beheco/arm144
Soumi, S. J. (2011). Risk, resilience, and gene-environment interplay in primates. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 289–297.
Stearns, S. C. (1992). The evolution of life histories. Oxford, England: Oxford University
Press.
Stevenson-Hinde, J., & Zunz, M. (1978). Subjective assessment of individual rhesus
monkeys. Primates, 19, 473–482.
Tooby, J., & Cosmides, L. (1990). On the universality of human nature and the uniqueness of the individual: The role of genetics and adaptation. Journal of Personality,
58(1), 17–67. doi:10.1111/j.1467-6494.1990.tb00907.x

12

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Verweij, K. J. H., Yang, J., Lahti, J., Veijola, J., Hintsanen, M., Pulkki-Råback, L., …
Zietsch, B. P. (2012). Maintenance of genetic variation in human personality: Testing evolutionary models by estimating heritability due to common causal variants and investigating the effect of distant inbreeding. Evolution, 66, 3238–3251.
doi:10.1111/j.1558-5646.2012.01679.x
Wilson, D. S., Clark, A. B., Coleman, K., & Dearstyne, T. (1994). Shyness and boldness in humans and other animals. Trends in Ecology and Evolution, 9, 442–446.
doi:10.1016/0169-5347(94)90134-1
Wolf, M., Doorn, G. S., van Leimar, O., & Weissing, F. J. (2007). Life-history trade-offs
favour the evolution of animal personalities. Nature, 447, 581–584. doi:10.1038/
nature05835

JOSEPH H. MANSON SHORT BIOGRAPHY
Joseph H. Manson (http://www.sscnet.ucla.edu/anthro/faculty/jmanson/
Home.html) is a Professor of Anthropology at the University of California,
Los Angeles. He has published studies of female mate choice in free-ranging
rhesus macaques and numerous topics, including personality structure,
in wild white-faced capuchin monkeys. More recently, he has studied the
interplay between a human personality trait, psychopathy, and face-to-face
interaction and economic game-play decisions in small groups of previously
unacquainted people. His current research uses audio sampling of individuals’ daily lives to test hypotheses about personality variation drawn from
life history theory.
LYNN A. FAIRBANKS SHORT BIOGRAPHY
Lynn A. Fairbanks (http://www.bec.ucla.edu/faculty.php?id=34) is an
Emeritus Professor of Psychiatry and Biobehavioral Sciences at the University of California, Los Angeles. She has published numerous articles on
individual differences in temperament and personality of vervet monkeys,
focusing on the contributions of genetic, maternal, and contextual influences
on variation in novelty seeking, impulsivity, sociability, and response
to stressful life events. Her research on variation in maternal behavior
illustrates the tradeoffs between maternal diet and condition, maternal
investment, and offspring response and resilience in the development
of behavioral differences. The eight-generation extended pedigree of the
Vervet Research Colony has allowed identification of genetic influences and
effects of gene–environment interactions on behavioral and physiological
traits.

Evolutionary Perspectives on Animal and Human Personality

13

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