Emerging Trends in The Social and Behavioral Sciences

Primate Allomaternal Care

Item

Title

Primate Allomaternal Care

Author

Tecot, Stacey

Baden, Andrea L.

Research Area

Social Interactions

Topic

Primate Studies

Abstract

Allomaternal care (AMC) (i.e., infant care that is provided by group members other than an infant's mother) is a rare, although phylogenetically widespread, mammalian infant care strategy. In primates, however, AMC occurs at unusually high frequencies, particularly among several haplorhine (monkey and ape) taxa. In fact, AMC is present in every major primate radiation and has been described in 74% of 154 species for which data are available. Its widespread presence in the Order Primates suggests that there may have been strong selective pressure for AMC early in primate evolution, but it is currently unknown why these behaviors are so common in primates. Research focused on captive callitrichids (tamarins and marmosets) has contributed greatly to our understanding of the potential causes and consequences of highly derived forms of AMC (i.e., cooperative breeding). Recent efforts have shifted focus to understand the selective pressures leading to the expansion and diversification of AMC throughout the Primate Order, thus expanding research to investigate the causes and consequences of less derived forms of AMC. Here we review the broad‐scale patterns observed in primates and outline innovative and exciting avenues of research moving forward.

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Identifier

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extracted text

Primate Allomaternal Care
STACEY TECOT and ANDREA L. BADEN

Abstract
Allomaternal care (AMC) (i.e., infant care that is provided by group members
other than an infant’s mother) is a rare, although phylogenetically widespread,
mammalian infant care strategy. In primates, however, AMC occurs at unusually
high frequencies, particularly among several haplorhine (monkey and ape) taxa.
In fact, AMC is present in every major primate radiation and has been described
in 74% of 154 species for which data are available. Its widespread presence in the
Order Primates suggests that there may have been strong selective pressure for
AMC early in primate evolution, but it is currently unknown why these behaviors
are so common in primates. Research focused on captive callitrichids (tamarins and
marmosets) has contributed greatly to our understanding of the potential causes
and consequences of highly derived forms of AMC (i.e., cooperative breeding).
Recent efforts have shifted focus to understand the selective pressures leading
to the expansion and diversification of AMC throughout the Primate Order, thus
expanding research to investigate the causes and consequences of less derived forms
of AMC. Here we review the broad-scale patterns observed in primates and outline
innovative and exciting avenues of research moving forward.

INTRODUCTION
Allomaternal care (AMC) is infant care provided by individuals other than
the genetic mother (e.g., fathers, siblings, aunts, uncles, or unrelated individuals, termed helpers), including several seemingly altruistic behaviors such as
babysitting, carrying, nursing, crèching, or huddling for thermoregulation.
Although AMC has been observed in several taxonomically diverse species
(e.g., birds, social insects, and mammals), mammalian mothers are typically
the sole providers of infant care and AMC is uncommon. However, recent
research indicates that AMC is notably abundant in primates, suggesting that
relatively strong selective pressures helped shape this behavior early in our
evolution.
AMC was the likely evolutionary antecedent to cooperative breeding—a
more derived form of AMC including infant provisioning, that evolved
in only a few species including the callitrichids (tamarins, marmosets)
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

and humans. Cooperative breeding is ubiquitous among humans, and
proposed to have been profoundly important during human evolution:
Mothers and offspring gained significant energetic benefits, enabling higher
maternal fertility, protracted infant development, and less costly brain
growth, which ultimately led to emotionally modern brains (Hrdy, 2009). It
is thought that when the cognitive abilities shared by apes and our earliest
human ancestors merged with these underlying prosocial motivations,
“shared intentionality”—a social disposition identified as the source of
many uniquely human traits, such as culture and language—emerged
(Burkart, Hrdy, & van Schaik, 2009). These traits allowed our ancestors,
and eventually modern humans, to forge deeper social relationships, and
cooperate on an unparalleled level. In short, prosocial behaviors associated
with ancestral forms of shared infant care (i.e., AMC) paved the way for us
becoming human.
FOUNDATIONAL RESEARCH
WHO CARES?
The study of primate AMC has traditionally focused on New World and Old
World monkeys. Until recently, AMC in primates was viewed as exceptional,
and thought to be entirely absent in one of the two primate suborders (strepsirrhines, i.e., lemurs, lorises, galagos). As data have accumulated, scientists
have been surprised to discover that primate AMC is both widespread and
common. Nearly 75% of primate species display some type of AMC (Table 1).
By suborder, AMC is present in 61% of strepsirrhines, and 76% of haplorhines
(monkeys, apes including humans) for which there are data.
Currently, it is difficult to make many meaningful statements about the
abundance of AMC because (i) we lack solid empirical data for many
species; (ii) estimates are heavily impacted by the number of species in the
given taxonomic group; and (iii) these broad-scale analyses do not consider
intra-specific variation. However, it is notable that AMC is present in 100%
of callitrichids (tamarins, marmosets). Perhaps even more remarkable,
because AMC was thought to be absent in strepsirrhines until just recently,
is the frequency at which AMC occurs in several of the nocturnal, solitary
and pair-living cheirogaleids (dwarf lemurs, mouse lemurs). Pair-living
males babysit (Fietz & Dausmann, 2003), and although solitary species were
once thought to have “little or no opportunity for nonmaternal care” (Ross
& MacLarnon, 2000, p. 94), ‘solitary’ females communally nest their infants
and share in allomaternal suckling (Eberle & Kappeler, 2006). It should
be noted, however, that we lack data for three of five cheirogaleid genera,
reinforcing the fact that more information is still needed. Both callitrichids

Primate Allomaternal Care

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Table 1
Phylogenetic Distribution of Allomaternal Care in the Order Primates
N
Source

AMC

Species Strep Hap AMC
Strep Hap
excluding (%)
(%)
protection
(%)

Isler and van
98
Schaik (2012)
Hrdy (2010)
120
Tecot et al.
23
(2012, 2013)
Combined
109
dataset: Isler
and van
Schaik (2012),
Tecot et al.
(2012, 2013)
All datasets
154
combined

Carrying
Strep Hap
(%)
(%)

Notes

20

78

72.00

27
23

93
0

68.33
65.22

65.00 74.36 45.00 58.97 445 mammals
48.15 75.27 N/A N/A Primates
65.22 N/A 34.78 N/A Lemurids

78

31

71.50

64.52 74.36 48.39 58.97 —

31

123 74.03

61.29 76.42 N/A

N/A

—

Combining databases by Hrdy and Tecot (unpublished data, available in All the World’s Primates
Database), Isler and van Schaik (2012), Tecot et al. (2012), and Tecot, Baden, Romine, and Kamilar (2013).
Strep, strepsirrhines; Hap, haplorhines.

and cheirogaleids comprise several litter-bearing species for which helpers
alleviate maternal energetic burden and increase infant survival (Bales,
Baker, Miller, & Tardif, 2000; Fietz & Dausmann, 2003). Despite the fact that
the majority of the remaining primates bear singletons, AMC by fathers,
other relatives, and unrelated individuals occurs throughout the Order.
AMC by adult males is generally strongest in species where paternity is
certain. Male care is most common among pair-living taxa, including at least
two lemur species (mongoose lemurs, red-bellied lemurs; Figure 1), several
New World monkeys (tamarins, marmosets, titis, owl monkeys), and some
apes (siamangs, humans). In cases where females are not monopolizable and
males can maximize their reproductive success by living with a pair-mate
rather than seeking out multiple females, the benefits of paternal care are
clear. However, even resident males who are unrelated to the mother and
infant will sometimes provide care to extra-pair young (fat-tailed dwarf
lemurs, Fietz et al., 2000).
In group-living species with AMC, some adult males also provide infant
care, and not necessarily more often to their own genetic offspring (Ménard
et al., 2001). More often, nulliparous females (i.e., females who have not borne
offspring) provide care. Juvenile helpers of both sexes are generally older

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Figure 1 Red-bellied lemur (Eulemur rubriventer) male carrying an infant while
traveling in Vatoharanana, Ranomafana National Park, Madagascar. Source:
Photo credit Lahitsara Jean Pierre.

siblings, but help is not always directed towards relatives (Fairbanks, 1990),
and cannot be explained entirely by kin selection. Although AMC among
adult females is most common in female bonded species (i.e., those with little
female emigration and high female relatedness), allomothering also occurs
in species in which both sexes emigrate (capped langurs, Stanford, 1992),
although to a much lesser degree (Bennett & Davies, 1994). Despite this, AMC
is never prevalent in species characterized by male philopatry (i.e., where
males remain in their natal groups), except perhaps in anomalous cases of
maternal death.

Primate Allomaternal Care

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WHY HELP? ADAPTIVE VALUE OF AMC
Traditionally, studies of AMC have focused on the benefits to caregivers
because helping and cooperation seemed paradoxical in light of evolutionary theory: Why should fathers invest in one infant when they can
produce several progeny by mating with additional females? Why should
individuals invest in infants who are not their own, sometimes foregoing
their own reproduction to do so? While several forms of AMC may not be
costly (e.g., huddling with infants for thermoregulation), contributing time
and energy to infants can be (Heinsohn & Legge, 1999). Babysitters can
suffer drastic reductions in body mass by sacrificing time normally allocated
to foraging and feeding (Clutton-Brock et al., 1998), carrying infants makes
travel more energetically expensive and awkward (Altmann & Samuels,
1992), and in extreme cases, one’s own reproduction may be suppressed
(Solomon & French, 1997). Despite the associated costs of AMC, studies
have revealed that helpers can gain direct benefits by, for example, learning to parent and subsequently increasing their own offspring’s survival
(vervet monkeys, Fairbanks, 1990), or by securing an infrequently available
breeding position (marmosets, Abbott, Digby, & Saltzman, 2009). They can
also benefit indirectly by providing care to related offspring and increasing
their inclusive fitness (Briga, Pen, & Wright, 2012; Hamilton, 1964), and
even by caring for unrelated individuals via mutualism (black-and-white
ruffed lemurs, Baden, Wright, Louis, & Bradley 2013), or reciprocal altruism
(capuchins, O’Brien & Robinson, 1991). Thus, AMC may represent an
optimal reproductive strategy, yielding relatively higher fitness pay-offs to
caregivers than alternative scenarios.
WHAT ABOUT MOTHERS? ADAPTIVE VALUE TO MOTHERS AND THEIR OFFSPRING
Many primate females are “continuous care and contact” mothers (Hrdy,
2009), who prohibit others from interacting with their offspring, presumably
because of potential threats such as negative infant handling and infanticide that can severely and directly impact infant survival. But mothers who
allow others to help them rear their young can benefit in dramatic ways. In
cooperative breeders, relatively greater AMC can increase an infant’s quality of care, health, and survival, and a mother’s reproductive rate (humans,
Egeland & Hiester, 1995; Sear, Mace, & McGregor, 2000; callitrichids, Bales
et al., 2000). Broad, comparative analyses determined that haplorhine mothers receiving help reproduce faster than mothers without help and may ultimately experience relatively higher reproductive success (Mitani & Watts,
1997). However, these effects on fertility are absent in lemurids (Tecot et al.,
2012) and nonprimate mammals (Isler & van Schaik, 2012). These divergent
results may indicate distinctive selective pressures for haplorhines, or reflect

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

the very strong influence of callitrichids on these analyses. As cooperative
breeders, litter-bearing callitrichids have a highly derived form of AMC that
includes infant provisioning, and that potentially allows offspring to grow
quickly and at less of an energetic cost to mothers, who often resume cycling
soon after birth. It appears that this extensive form of AMC largely drove
the positive relationship between AMC and fertility in haplorhines (Isler &
van Schaik, 2012). At the same time, fetal and infant growth rates for strepsirrhines are only available from provisioned, captive animals, which may
result in overestimated growth rates in species lacking AMC. Data on more
taxa will help determine whether these relationships hold true for noncooperatively breeding haplorhines, and whether the benefits to strepsirrhines
have been underestimated.
Additional hypotheses for the evolution of AMC in primates have been
tested using broad-scale comparative analyses, but caution should be used
in interpreting such studies. Comparative meta-analyses fail to consider
inter-individual variation and/or the fluctuating selection pressures at the
intraspecific level under which primate sociality has evolved (Strier, 2009).
Therefore, they may not provide the level of resolution needed to determine
the adaptive benefits of AMC in species where individual care is facultative
(i.e., can but does not always occur), or the selective pressures leading to
the expression of AMC. For example, in testing whether maternal energetic
stress favors the evolution of AMC (owing to energetic savings afforded
mothers), Ross and MacLarnon (2000) were limited in using species dietary
categories as proxies for nutritional stress. Because species have evolved
adaptations to successfully extract nutrients from their dietary items, an
ideal test of the relationships between energetic stress and AMC might be
one that is conducted among species sharing a dietary guild. Individual-level
investigations within a single species might be most informative in helping
to address what internal states and social and physical environments select
for AMC, and whether and how the quality and quantity of AMC influences
reproductive success (Mitani & Watts, 1997).
PROXIMATE MECHANISMS PROMOTING AMC
Individual variation can help identify environmental pressures selecting
for and prohibiting AMC. Maternal size, litter size, and group size are all
associated with variation in AMC (Bales, French, & Dietz, 2002), indicating
that AMC can release individuals from certain reproductive constraints. It is
also possible that energetic need drives maternal tolerance of AMC (Ross &
MacLarnon, 2000), such that lower-ranking mothers, mothers bearing twins,
or mothers with older dependent offspring would allow AMC to a greater

Primate Allomaternal Care

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extent than higher-ranking mothers, mothers bearing singletons, or mothers
who recently gave birth.
There is growing consensus that the physiological mechanisms promoting
and maintaining maternal care may also facilitate AMC (Ziegler, 2000).
Mothers undergo critical endocrine changes during pregnancy and lactation
that have evolved to enhance responsiveness to offspring (Saltzman &
Maestripieri, 2011). More recently, research examining the endocrinological
profiles of fathers found that they respond to their mate’s pregnancy (Ziegler,
Washabaugh, & Snowdon, 2004) and to infants themselves, indicating that
paternal hormonal changes can facilitate, maintain, or prime individuals
for care. For example, there is abundant support for an inverse relationship
between paternal care and testosterone, which may decrease the likelihood
of infant-directed aggression, or reflect the trade-off between mating and
parenting effort (Wingfield, Hegner, Dufty, & Ball, 1990). In humans, paternal testosterone decreases pre- to postpartum (Storey, Delahunty, McKay,
Walsh, & Wilhelm, 2006), and after mating and siring offspring (Gettler,
McDade, Feranil, & Kuzawa, 2011). Testosterone levels decrease once males
become fathers, and are lower in those who invest more (Gettler et al.,
2011; Nunes, Fite, Patera, & French, 2001). The neuropeptide prolactin has
several hundred biological actions, including stimulating female lactation,
inhibiting male sexual behavior, and mediating parental behavior (Freeman,
Kanyicska, Lerant, & Nagy, 2000). This hormone also responds to carrying/
infant contact (cotton-top tamarins, common marmosets, Ziegler, 2000),
infant cries, and play (humans, Fleming, Corter, Stallings, & Steiner, 2002)
in fathers. Ziegler, Prudom, Zahed, Parlow, and Wegner (2009) found that
prolactin elevations even buffered experienced fathers from weight loss
associated with infant carrying, thus reducing energetic costs.
To our knowledge, very little research has examined the hormonal mechanisms underlying AMC in nonparental helpers (i.e., alloparental care),
although help from these individuals is hypothesized to be essential (Hrdy,
2009). Higher levels of vasopressin (which promotes offspring care) in
grandmothers than control women (Gray & Samms-Vaughan, 2009), and
elevated prolactin levels in cooperatively breeding nonprimate babysitters
that are otherwise absent in nonhelpers (meerkats, Carlson et al., 2006)
suggest that alloparental care also can have a hormonal basis. Variation
in hormone levels can thus help explain variation in AMC, although this
research is still in its infancy, particularly as it pertains to free-living individuals. Extending this research to nonparental helpers would provide a
critical test of the importance of hormonal mechanisms for the expression of
infant care. It is also essential to understand how different individuals have
been shaped by natural selection to help, not only in nonhuman primates,
but also in our own evolutionary history.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Because the observation that AMC is widespread in primates occurred
recently, a disparity of appropriate models has resulted in a research focus
on a very limited set of primate species: the callitrichids. Two species in
particular (Callithrix jacchus, Saguinus oedipus) have contributed the vast
majority of what we know of primate hormones facilitating AMC. Therefore,
we still know very little about the role that hormones play in the expression
of AMC in the majority of species. One recent study by Rafacz, Margulis,
and Santymire (2012) of bi-parental and exclusively maternal hylobatids
(siamangs and gibbons, respectively) suggests that the same mechanisms
are at work in species with less specialized paternal care. Future research on
these mechanisms in species with facultative AMC will be fundamental in
determining how adaptable (and critical) these systems are, and whether all
primate AMC is rooted in such adaptability.
CUTTING EDGE RESEARCH
Outside of studies with humans, the bulk of the work described herein has
been conducted in captivity, largely owing to the fact that, until relatively
recently, noninvasive hormonal sampling was difficult, if not impossible
(Ziegler & Wittwer, 2005). Experimental studies have been particularly
influential on contemporary studies of hormone-behavior relationships.
They identified several hormones of interest, partly through selectively
blocking their expression and observing effects on behavior, or injecting
exogenous hormone, and were at times able to determine cause and effect. It
is now well recognized that fecal metabolites can provide reliable measures
of steroids such as cortisol and androgens, they parallel serum levels, and
have been used in numerous studies as long-term (i.e., not acute) measures
of adrenal and gonadal axis activity (Tecot, 2013). Recent work indicates that
not only steroids, but also oxytocin and vasopressin, bonding hormones of
potential interest in AMC research, and prolactin can be measured reliably
in urine (Seltzer & Ziegler, 2007; Soltis, Wegner, & Newman, 2005). Armed
with the ability to make predictions about hormones and the expression of
AMC in variable social and mating structures, and the logistical feasibility
of extracting these hormones from noninvasively collected samples, we can
now investigate the mechanisms involved in facilitating and maintaining
AMC in the natural environments in which they evolved.
Recent work in the field of behavioral genetics has revealed that variation
in behavioral style (i.e., personality) can be explained, in part, by variation
at the genotypic level (Bradley & Lawler, 2011), opening new and exciting avenues of inquiry. Although few investigations have examined the
genetic basis of parental care in primates, parental effort does appear to
have a significant heritable component in other animals (Komdeur, 2006).

Primate Allomaternal Care

9

For example, variation in the arginine vasopressin 1a gene (AVPR1a) in
prairie voles has been linked to the quality and quantity of paternal care
(Hammock & Young, 2005). Although evidence from field studies are more
tenuous (Ophir, Campbell, Hanna, & Phelps, 2008; Solomon et al., 2009),
together, captive and wild-based studies provide strong evidence indicating
the importance of this gene region in mediating social behavior (Fink,
Excoffier, & Heckel, 2006; Heckel & Fink, 2008).
In humans, AVPR1a variants have been linked to altruistic tendencies
(Israel et al., 2008) and the propensity for men to form long-term, content partnerships (Walum et al., 2008). Recent surveys have identified significant intraand interspecific AVPR1a sequence variation across nearly all major primate
radiations (Anestis et al., 2014; Babb, Fernandez-Duque, & Schurr, 2010;
Hong et al., 2009; Rosso, Keller, Kaessmann, & Hammond, 2008) but to date,
researchers have been unable to link this variation to either social or mating
system in primates (Hong et al., 2009). However, recent studies have found
links between microsatellite polymorphisms (i.e., repeating sequences of
DNA) and various personality traits, including conscientiousness (Hopkins,
Donaldson, & Young, 2012) and friendliness (Anestis et al., 2014).
Although most work has focused on AVPR1a, several other promising
candidate genes have also been linked to parental behavior. For example,
more than 30 single nucleotide polymorphisms (i.e., DNA sequence variation occurring when a single nucleotide—A, T, C or G—differs among
members of a population) are known in the OXTR gene region (Israel et al.,
2008). OXTR gene polymorphisms have been associated with several social
behaviors, including empathy (Rodrigues, Saslow, Garcia, John, & Keltner,
2009), prosociality (Kogan et al., 2011), and both maternal (Francis, Young,
Meaney, & Insel, 2002) and paternal sensitivity (Bakermans-Kranenburg &
van Ijzendoorn, 2008). While results from captive studies are intriguing,
little if any work has focused on the links between OXTR variation and
personality in the wild.
KEY ISSUES FOR FUTURE RESEARCH
Work in the last 4 years has substantially increased our understanding of how
widespread AMC is, thus increasing (i) the power of comparative analyses,
(ii) our ability to look for broad patterns of selection, and (iii) the availability
of suitable species of study. However, we still lack complete data on the distribution of primate AMC, which can skew comparative analyses. We therefore
encourage researchers to broaden their taxonomic focus and also report AMC
behaviors whenever possible (and noting its absence in cases where AMC is

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

never observed). Furthermore, armed with increasingly sophisticated technologies, researchers can begin to address not only the AMC behaviors themselves, but also the endocrinological, molecular, and energetic underpinnings
of AMC.
Finally, It is important to consider the delicate balance between generating
high-resolution data (i.e., frequent, high intensity sampling) and large
sample size (i.e., many individuals from several social groups). While
studies of some species can easily meet both criteria (e.g., cercopithecids),
many other species live in strikingly smaller social groups, particularly the
strepsirrhines. Researchers are thus faced with the difficult trade-off between
achieving fine-grained behavioral resolution and statistical power. This issue
is further compounded in species with facultative AMC. This does not mean
that studies aren’t worthwhile. In these cases, collecting high-resolution data
from a relatively small, hopefully representative sample of focal individuals
is preferable to neglecting to study taxa at all.
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Saltzman, W., & Maestripieri, D. (2011). The neuroendocrinology of primate maternal behavior. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 35,
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Ziegler, T., Prudom, S., Zahed, S., Parlow, A., & Wegner, F. (2009). Prolactin’s mediative role in male parenting in parentally experienced marmosets (Callithrix jacchus). Hormones and Behavior, 56, 436–443.

FURTHER READING
Chism, J. (2000). Allocare patterns among cercopithecines. Folia Primatologica, 71,
55–66.
Donaldson, Z., & Young, L. (2008). Oxytocin, vasopressin, and the neurogenetics of
sociality. Science, 322, 900–904.
Emlen, S. (1991). Evolution of cooperative breeding in birds and mammals. In J. R.
Krebs & N. B. Davies (Eds.), Behavioural ecology: An evolutionary approach (3rd ed.,
pp. 301–335). Oxford, England: Blackwell Scientific.
Fernandez-Duque, E., Valeggia, C., & Mendoza, S. (2009). The biology of paternal care in human and nonhuman primates. Annual Review of Anthropology, 38,
115–130.
Hrdy, S. (2009). Mothers and others: The evolutionary origins of mutual understanding.
Cambridge, MA: Belknap Press of Harvard University Press.
Isler, K., & van Schaik, C. (2012). Allomaternal care, life history and brain size evolution in mammals. Journal of Human Evolution, 63, 52–63.
Israel, S., Lerer, E., Shalev, I., Uzefovsky, F., Reibold, M., Bachner-Melman, R., … ,
Ebstein, R. (2008). Molecular genetic studies of the arginine vasopressin 1a receptor (AVPR1a) and the oxytocin receptor (OXTR) in human behavior: From autism
to altruism with some notes in between. Progress in Brain Research, 170, 435–449.
Ross, C. (2003). Life history, infant care strategies, and brain size in primates. In P. M.
Kappeler & M. E. Pereira (Eds.), Primate life histories and socioecology (pp. 266–284).
Chicago, IL: University of Chicago Press.
Ross, C., & MacLarnon, A. (2000). The evolution of non-maternal care in anthropoid
primates: A test of the hypotheses. Folia Primatologica, 71, 93–113.
Tecot, S., Baden, A., Romine, N., & Kamilar, J. (2013). Reproductive strategies and
infant care in the Malagasy primates. In K. Clancy, K. Hinde & J. Rutherford (Eds.),
Building babies: Primate development in proximate and ultimate perspective. Developments in primatology: Progress and prospects (pp. 321–359). New York, NY:
Springer.
Whitten, P., Brockman, D., & Stavisky, R. (1998). Recent advances in noninvasive
techniques to monitor hormone-behavior interactions. Yearbook of Physical Anthropology, 27(Suppl.), 1–23.
Ziegler, T. (2000). Hormones associated with non-maternal infant care: A review of
mammalian and avian studies. Folia Primatologica, 71, 6–21.

STACEY TECOT SHORT BIOGRAPHY
Stacey Tecot, PhD is an Assistant Professor at the University of Arizona,
the Director of the Laboratory for the Evolutionary Endocrinology of Primates, and co-director of the Ranomafana Red-Bellied Lemur Project. She is

Primate Allomaternal Care

15

a biological anthropologist with training in primate behavior and socio- and
eco-endocrinology. She integrates fieldwork in Madagascar with hormone
assay development in the laboratory to understand how species mitigate
environmental challenges, with a current emphasis on the evolution of primate allomaternal care. More information on her research can be found at the
following Web sites:
http://www.stecot.weebly.com,
http://anthropology.arizona.edu/user/stacey-tecot,
http://www.leep.arizona.edu

ANDREA L. BADEN SHORT BIOGRAPHY
Andrea L. Baden, PhD is an Assistant Professor at Hunter College, City
University of New York and Director of Hunter’s Primate Molecular Ecology
Lab. She is a biological anthropologist with training in primate behavior
and molecular ecology. Her research integrates traditional fieldwork in
Madagascar and molecular genetic techniques to answer larger evolutionary questions regarding primate social and reproductive strategies,
with a current emphasis on the evolution of primate allomaternal care.
More information on her research can be found at the following Web sites:
http://andra581.wix.com/andreabaden, http://www.nycep.org/faculty/
andrea-baden

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16

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

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Primate Allomaternal Care
STACEY TECOT and ANDREA L. BADEN

Abstract
Allomaternal care (AMC) (i.e., infant care that is provided by group members
other than an infant’s mother) is a rare, although phylogenetically widespread,
mammalian infant care strategy. In primates, however, AMC occurs at unusually
high frequencies, particularly among several haplorhine (monkey and ape) taxa.
In fact, AMC is present in every major primate radiation and has been described
in 74% of 154 species for which data are available. Its widespread presence in the
Order Primates suggests that there may have been strong selective pressure for
AMC early in primate evolution, but it is currently unknown why these behaviors
are so common in primates. Research focused on captive callitrichids (tamarins and
marmosets) has contributed greatly to our understanding of the potential causes
and consequences of highly derived forms of AMC (i.e., cooperative breeding).
Recent efforts have shifted focus to understand the selective pressures leading
to the expansion and diversification of AMC throughout the Primate Order, thus
expanding research to investigate the causes and consequences of less derived forms
of AMC. Here we review the broad-scale patterns observed in primates and outline
innovative and exciting avenues of research moving forward.

INTRODUCTION
Allomaternal care (AMC) is infant care provided by individuals other than
the genetic mother (e.g., fathers, siblings, aunts, uncles, or unrelated individuals, termed helpers), including several seemingly altruistic behaviors such as
babysitting, carrying, nursing, crèching, or huddling for thermoregulation.
Although AMC has been observed in several taxonomically diverse species
(e.g., birds, social insects, and mammals), mammalian mothers are typically
the sole providers of infant care and AMC is uncommon. However, recent
research indicates that AMC is notably abundant in primates, suggesting that
relatively strong selective pressures helped shape this behavior early in our
evolution.
AMC was the likely evolutionary antecedent to cooperative breeding—a
more derived form of AMC including infant provisioning, that evolved
in only a few species including the callitrichids (tamarins, marmosets)
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.

1

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

and humans. Cooperative breeding is ubiquitous among humans, and
proposed to have been profoundly important during human evolution:
Mothers and offspring gained significant energetic benefits, enabling higher
maternal fertility, protracted infant development, and less costly brain
growth, which ultimately led to emotionally modern brains (Hrdy, 2009). It
is thought that when the cognitive abilities shared by apes and our earliest
human ancestors merged with these underlying prosocial motivations,
“shared intentionality”—a social disposition identified as the source of
many uniquely human traits, such as culture and language—emerged
(Burkart, Hrdy, & van Schaik, 2009). These traits allowed our ancestors,
and eventually modern humans, to forge deeper social relationships, and
cooperate on an unparalleled level. In short, prosocial behaviors associated
with ancestral forms of shared infant care (i.e., AMC) paved the way for us
becoming human.
FOUNDATIONAL RESEARCH
WHO CARES?
The study of primate AMC has traditionally focused on New World and Old
World monkeys. Until recently, AMC in primates was viewed as exceptional,
and thought to be entirely absent in one of the two primate suborders (strepsirrhines, i.e., lemurs, lorises, galagos). As data have accumulated, scientists
have been surprised to discover that primate AMC is both widespread and
common. Nearly 75% of primate species display some type of AMC (Table 1).
By suborder, AMC is present in 61% of strepsirrhines, and 76% of haplorhines
(monkeys, apes including humans) for which there are data.
Currently, it is difficult to make many meaningful statements about the
abundance of AMC because (i) we lack solid empirical data for many
species; (ii) estimates are heavily impacted by the number of species in the
given taxonomic group; and (iii) these broad-scale analyses do not consider
intra-specific variation. However, it is notable that AMC is present in 100%
of callitrichids (tamarins, marmosets). Perhaps even more remarkable,
because AMC was thought to be absent in strepsirrhines until just recently,
is the frequency at which AMC occurs in several of the nocturnal, solitary
and pair-living cheirogaleids (dwarf lemurs, mouse lemurs). Pair-living
males babysit (Fietz & Dausmann, 2003), and although solitary species were
once thought to have “little or no opportunity for nonmaternal care” (Ross
& MacLarnon, 2000, p. 94), ‘solitary’ females communally nest their infants
and share in allomaternal suckling (Eberle & Kappeler, 2006). It should
be noted, however, that we lack data for three of five cheirogaleid genera,
reinforcing the fact that more information is still needed. Both callitrichids

Primate Allomaternal Care

3

Table 1
Phylogenetic Distribution of Allomaternal Care in the Order Primates
N
Source

AMC

Species Strep Hap AMC
Strep Hap
excluding (%)
(%)
protection
(%)

Isler and van
98
Schaik (2012)
Hrdy (2010)
120
Tecot et al.
23
(2012, 2013)
Combined
109
dataset: Isler
and van
Schaik (2012),
Tecot et al.
(2012, 2013)
All datasets
154
combined

Carrying
Strep Hap
(%)
(%)

Notes

20

78

72.00

27
23

93
0

68.33
65.22

65.00 74.36 45.00 58.97 445 mammals
48.15 75.27 N/A N/A Primates
65.22 N/A 34.78 N/A Lemurids

78

31

71.50

64.52 74.36 48.39 58.97 —

31

123 74.03

61.29 76.42 N/A

N/A

—

Combining databases by Hrdy and Tecot (unpublished data, available in All the World’s Primates
Database), Isler and van Schaik (2012), Tecot et al. (2012), and Tecot, Baden, Romine, and Kamilar (2013).
Strep, strepsirrhines; Hap, haplorhines.

and cheirogaleids comprise several litter-bearing species for which helpers
alleviate maternal energetic burden and increase infant survival (Bales,
Baker, Miller, & Tardif, 2000; Fietz & Dausmann, 2003). Despite the fact that
the majority of the remaining primates bear singletons, AMC by fathers,
other relatives, and unrelated individuals occurs throughout the Order.
AMC by adult males is generally strongest in species where paternity is
certain. Male care is most common among pair-living taxa, including at least
two lemur species (mongoose lemurs, red-bellied lemurs; Figure 1), several
New World monkeys (tamarins, marmosets, titis, owl monkeys), and some
apes (siamangs, humans). In cases where females are not monopolizable and
males can maximize their reproductive success by living with a pair-mate
rather than seeking out multiple females, the benefits of paternal care are
clear. However, even resident males who are unrelated to the mother and
infant will sometimes provide care to extra-pair young (fat-tailed dwarf
lemurs, Fietz et al., 2000).
In group-living species with AMC, some adult males also provide infant
care, and not necessarily more often to their own genetic offspring (Ménard
et al., 2001). More often, nulliparous females (i.e., females who have not borne
offspring) provide care. Juvenile helpers of both sexes are generally older

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Figure 1 Red-bellied lemur (Eulemur rubriventer) male carrying an infant while
traveling in Vatoharanana, Ranomafana National Park, Madagascar. Source:
Photo credit Lahitsara Jean Pierre.

siblings, but help is not always directed towards relatives (Fairbanks, 1990),
and cannot be explained entirely by kin selection. Although AMC among
adult females is most common in female bonded species (i.e., those with little
female emigration and high female relatedness), allomothering also occurs
in species in which both sexes emigrate (capped langurs, Stanford, 1992),
although to a much lesser degree (Bennett & Davies, 1994). Despite this, AMC
is never prevalent in species characterized by male philopatry (i.e., where
males remain in their natal groups), except perhaps in anomalous cases of
maternal death.

Primate Allomaternal Care

5

WHY HELP? ADAPTIVE VALUE OF AMC
Traditionally, studies of AMC have focused on the benefits to caregivers
because helping and cooperation seemed paradoxical in light of evolutionary theory: Why should fathers invest in one infant when they can
produce several progeny by mating with additional females? Why should
individuals invest in infants who are not their own, sometimes foregoing
their own reproduction to do so? While several forms of AMC may not be
costly (e.g., huddling with infants for thermoregulation), contributing time
and energy to infants can be (Heinsohn & Legge, 1999). Babysitters can
suffer drastic reductions in body mass by sacrificing time normally allocated
to foraging and feeding (Clutton-Brock et al., 1998), carrying infants makes
travel more energetically expensive and awkward (Altmann & Samuels,
1992), and in extreme cases, one’s own reproduction may be suppressed
(Solomon & French, 1997). Despite the associated costs of AMC, studies
have revealed that helpers can gain direct benefits by, for example, learning to parent and subsequently increasing their own offspring’s survival
(vervet monkeys, Fairbanks, 1990), or by securing an infrequently available
breeding position (marmosets, Abbott, Digby, & Saltzman, 2009). They can
also benefit indirectly by providing care to related offspring and increasing
their inclusive fitness (Briga, Pen, & Wright, 2012; Hamilton, 1964), and
even by caring for unrelated individuals via mutualism (black-and-white
ruffed lemurs, Baden, Wright, Louis, & Bradley 2013), or reciprocal altruism
(capuchins, O’Brien & Robinson, 1991). Thus, AMC may represent an
optimal reproductive strategy, yielding relatively higher fitness pay-offs to
caregivers than alternative scenarios.
WHAT ABOUT MOTHERS? ADAPTIVE VALUE TO MOTHERS AND THEIR OFFSPRING
Many primate females are “continuous care and contact” mothers (Hrdy,
2009), who prohibit others from interacting with their offspring, presumably
because of potential threats such as negative infant handling and infanticide that can severely and directly impact infant survival. But mothers who
allow others to help them rear their young can benefit in dramatic ways. In
cooperative breeders, relatively greater AMC can increase an infant’s quality of care, health, and survival, and a mother’s reproductive rate (humans,
Egeland & Hiester, 1995; Sear, Mace, & McGregor, 2000; callitrichids, Bales
et al., 2000). Broad, comparative analyses determined that haplorhine mothers receiving help reproduce faster than mothers without help and may ultimately experience relatively higher reproductive success (Mitani & Watts,
1997). However, these effects on fertility are absent in lemurids (Tecot et al.,
2012) and nonprimate mammals (Isler & van Schaik, 2012). These divergent
results may indicate distinctive selective pressures for haplorhines, or reflect

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

the very strong influence of callitrichids on these analyses. As cooperative
breeders, litter-bearing callitrichids have a highly derived form of AMC that
includes infant provisioning, and that potentially allows offspring to grow
quickly and at less of an energetic cost to mothers, who often resume cycling
soon after birth. It appears that this extensive form of AMC largely drove
the positive relationship between AMC and fertility in haplorhines (Isler &
van Schaik, 2012). At the same time, fetal and infant growth rates for strepsirrhines are only available from provisioned, captive animals, which may
result in overestimated growth rates in species lacking AMC. Data on more
taxa will help determine whether these relationships hold true for noncooperatively breeding haplorhines, and whether the benefits to strepsirrhines
have been underestimated.
Additional hypotheses for the evolution of AMC in primates have been
tested using broad-scale comparative analyses, but caution should be used
in interpreting such studies. Comparative meta-analyses fail to consider
inter-individual variation and/or the fluctuating selection pressures at the
intraspecific level under which primate sociality has evolved (Strier, 2009).
Therefore, they may not provide the level of resolution needed to determine
the adaptive benefits of AMC in species where individual care is facultative
(i.e., can but does not always occur), or the selective pressures leading to
the expression of AMC. For example, in testing whether maternal energetic
stress favors the evolution of AMC (owing to energetic savings afforded
mothers), Ross and MacLarnon (2000) were limited in using species dietary
categories as proxies for nutritional stress. Because species have evolved
adaptations to successfully extract nutrients from their dietary items, an
ideal test of the relationships between energetic stress and AMC might be
one that is conducted among species sharing a dietary guild. Individual-level
investigations within a single species might be most informative in helping
to address what internal states and social and physical environments select
for AMC, and whether and how the quality and quantity of AMC influences
reproductive success (Mitani & Watts, 1997).
PROXIMATE MECHANISMS PROMOTING AMC
Individual variation can help identify environmental pressures selecting
for and prohibiting AMC. Maternal size, litter size, and group size are all
associated with variation in AMC (Bales, French, & Dietz, 2002), indicating
that AMC can release individuals from certain reproductive constraints. It is
also possible that energetic need drives maternal tolerance of AMC (Ross &
MacLarnon, 2000), such that lower-ranking mothers, mothers bearing twins,
or mothers with older dependent offspring would allow AMC to a greater

Primate Allomaternal Care

7

extent than higher-ranking mothers, mothers bearing singletons, or mothers
who recently gave birth.
There is growing consensus that the physiological mechanisms promoting
and maintaining maternal care may also facilitate AMC (Ziegler, 2000).
Mothers undergo critical endocrine changes during pregnancy and lactation
that have evolved to enhance responsiveness to offspring (Saltzman &
Maestripieri, 2011). More recently, research examining the endocrinological
profiles of fathers found that they respond to their mate’s pregnancy (Ziegler,
Washabaugh, & Snowdon, 2004) and to infants themselves, indicating that
paternal hormonal changes can facilitate, maintain, or prime individuals
for care. For example, there is abundant support for an inverse relationship
between paternal care and testosterone, which may decrease the likelihood
of infant-directed aggression, or reflect the trade-off between mating and
parenting effort (Wingfield, Hegner, Dufty, & Ball, 1990). In humans, paternal testosterone decreases pre- to postpartum (Storey, Delahunty, McKay,
Walsh, & Wilhelm, 2006), and after mating and siring offspring (Gettler,
McDade, Feranil, & Kuzawa, 2011). Testosterone levels decrease once males
become fathers, and are lower in those who invest more (Gettler et al.,
2011; Nunes, Fite, Patera, & French, 2001). The neuropeptide prolactin has
several hundred biological actions, including stimulating female lactation,
inhibiting male sexual behavior, and mediating parental behavior (Freeman,
Kanyicska, Lerant, & Nagy, 2000). This hormone also responds to carrying/
infant contact (cotton-top tamarins, common marmosets, Ziegler, 2000),
infant cries, and play (humans, Fleming, Corter, Stallings, & Steiner, 2002)
in fathers. Ziegler, Prudom, Zahed, Parlow, and Wegner (2009) found that
prolactin elevations even buffered experienced fathers from weight loss
associated with infant carrying, thus reducing energetic costs.
To our knowledge, very little research has examined the hormonal mechanisms underlying AMC in nonparental helpers (i.e., alloparental care),
although help from these individuals is hypothesized to be essential (Hrdy,
2009). Higher levels of vasopressin (which promotes offspring care) in
grandmothers than control women (Gray & Samms-Vaughan, 2009), and
elevated prolactin levels in cooperatively breeding nonprimate babysitters
that are otherwise absent in nonhelpers (meerkats, Carlson et al., 2006)
suggest that alloparental care also can have a hormonal basis. Variation
in hormone levels can thus help explain variation in AMC, although this
research is still in its infancy, particularly as it pertains to free-living individuals. Extending this research to nonparental helpers would provide a
critical test of the importance of hormonal mechanisms for the expression of
infant care. It is also essential to understand how different individuals have
been shaped by natural selection to help, not only in nonhuman primates,
but also in our own evolutionary history.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Because the observation that AMC is widespread in primates occurred
recently, a disparity of appropriate models has resulted in a research focus
on a very limited set of primate species: the callitrichids. Two species in
particular (Callithrix jacchus, Saguinus oedipus) have contributed the vast
majority of what we know of primate hormones facilitating AMC. Therefore,
we still know very little about the role that hormones play in the expression
of AMC in the majority of species. One recent study by Rafacz, Margulis,
and Santymire (2012) of bi-parental and exclusively maternal hylobatids
(siamangs and gibbons, respectively) suggests that the same mechanisms
are at work in species with less specialized paternal care. Future research on
these mechanisms in species with facultative AMC will be fundamental in
determining how adaptable (and critical) these systems are, and whether all
primate AMC is rooted in such adaptability.
CUTTING EDGE RESEARCH
Outside of studies with humans, the bulk of the work described herein has
been conducted in captivity, largely owing to the fact that, until relatively
recently, noninvasive hormonal sampling was difficult, if not impossible
(Ziegler & Wittwer, 2005). Experimental studies have been particularly
influential on contemporary studies of hormone-behavior relationships.
They identified several hormones of interest, partly through selectively
blocking their expression and observing effects on behavior, or injecting
exogenous hormone, and were at times able to determine cause and effect. It
is now well recognized that fecal metabolites can provide reliable measures
of steroids such as cortisol and androgens, they parallel serum levels, and
have been used in numerous studies as long-term (i.e., not acute) measures
of adrenal and gonadal axis activity (Tecot, 2013). Recent work indicates that
not only steroids, but also oxytocin and vasopressin, bonding hormones of
potential interest in AMC research, and prolactin can be measured reliably
in urine (Seltzer & Ziegler, 2007; Soltis, Wegner, & Newman, 2005). Armed
with the ability to make predictions about hormones and the expression of
AMC in variable social and mating structures, and the logistical feasibility
of extracting these hormones from noninvasively collected samples, we can
now investigate the mechanisms involved in facilitating and maintaining
AMC in the natural environments in which they evolved.
Recent work in the field of behavioral genetics has revealed that variation
in behavioral style (i.e., personality) can be explained, in part, by variation
at the genotypic level (Bradley & Lawler, 2011), opening new and exciting avenues of inquiry. Although few investigations have examined the
genetic basis of parental care in primates, parental effort does appear to
have a significant heritable component in other animals (Komdeur, 2006).

Primate Allomaternal Care

9

For example, variation in the arginine vasopressin 1a gene (AVPR1a) in
prairie voles has been linked to the quality and quantity of paternal care
(Hammock & Young, 2005). Although evidence from field studies are more
tenuous (Ophir, Campbell, Hanna, & Phelps, 2008; Solomon et al., 2009),
together, captive and wild-based studies provide strong evidence indicating
the importance of this gene region in mediating social behavior (Fink,
Excoffier, & Heckel, 2006; Heckel & Fink, 2008).
In humans, AVPR1a variants have been linked to altruistic tendencies
(Israel et al., 2008) and the propensity for men to form long-term, content partnerships (Walum et al., 2008). Recent surveys have identified significant intraand interspecific AVPR1a sequence variation across nearly all major primate
radiations (Anestis et al., 2014; Babb, Fernandez-Duque, & Schurr, 2010;
Hong et al., 2009; Rosso, Keller, Kaessmann, & Hammond, 2008) but to date,
researchers have been unable to link this variation to either social or mating
system in primates (Hong et al., 2009). However, recent studies have found
links between microsatellite polymorphisms (i.e., repeating sequences of
DNA) and various personality traits, including conscientiousness (Hopkins,
Donaldson, & Young, 2012) and friendliness (Anestis et al., 2014).
Although most work has focused on AVPR1a, several other promising
candidate genes have also been linked to parental behavior. For example,
more than 30 single nucleotide polymorphisms (i.e., DNA sequence variation occurring when a single nucleotide—A, T, C or G—differs among
members of a population) are known in the OXTR gene region (Israel et al.,
2008). OXTR gene polymorphisms have been associated with several social
behaviors, including empathy (Rodrigues, Saslow, Garcia, John, & Keltner,
2009), prosociality (Kogan et al., 2011), and both maternal (Francis, Young,
Meaney, & Insel, 2002) and paternal sensitivity (Bakermans-Kranenburg &
van Ijzendoorn, 2008). While results from captive studies are intriguing,
little if any work has focused on the links between OXTR variation and
personality in the wild.
KEY ISSUES FOR FUTURE RESEARCH
Work in the last 4 years has substantially increased our understanding of how
widespread AMC is, thus increasing (i) the power of comparative analyses,
(ii) our ability to look for broad patterns of selection, and (iii) the availability
of suitable species of study. However, we still lack complete data on the distribution of primate AMC, which can skew comparative analyses. We therefore
encourage researchers to broaden their taxonomic focus and also report AMC
behaviors whenever possible (and noting its absence in cases where AMC is

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

never observed). Furthermore, armed with increasingly sophisticated technologies, researchers can begin to address not only the AMC behaviors themselves, but also the endocrinological, molecular, and energetic underpinnings
of AMC.
Finally, It is important to consider the delicate balance between generating
high-resolution data (i.e., frequent, high intensity sampling) and large
sample size (i.e., many individuals from several social groups). While
studies of some species can easily meet both criteria (e.g., cercopithecids),
many other species live in strikingly smaller social groups, particularly the
strepsirrhines. Researchers are thus faced with the difficult trade-off between
achieving fine-grained behavioral resolution and statistical power. This issue
is further compounded in species with facultative AMC. This does not mean
that studies aren’t worthwhile. In these cases, collecting high-resolution data
from a relatively small, hopefully representative sample of focal individuals
is preferable to neglecting to study taxa at all.
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FURTHER READING
Chism, J. (2000). Allocare patterns among cercopithecines. Folia Primatologica, 71,
55–66.
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pp. 301–335). Oxford, England: Blackwell Scientific.
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primates: A test of the hypotheses. Folia Primatologica, 71, 93–113.
Tecot, S., Baden, A., Romine, N., & Kamilar, J. (2013). Reproductive strategies and
infant care in the Malagasy primates. In K. Clancy, K. Hinde & J. Rutherford (Eds.),
Building babies: Primate development in proximate and ultimate perspective. Developments in primatology: Progress and prospects (pp. 321–359). New York, NY:
Springer.
Whitten, P., Brockman, D., & Stavisky, R. (1998). Recent advances in noninvasive
techniques to monitor hormone-behavior interactions. Yearbook of Physical Anthropology, 27(Suppl.), 1–23.
Ziegler, T. (2000). Hormones associated with non-maternal infant care: A review of
mammalian and avian studies. Folia Primatologica, 71, 6–21.

STACEY TECOT SHORT BIOGRAPHY
Stacey Tecot, PhD is an Assistant Professor at the University of Arizona,
the Director of the Laboratory for the Evolutionary Endocrinology of Primates, and co-director of the Ranomafana Red-Bellied Lemur Project. She is

Primate Allomaternal Care

15

a biological anthropologist with training in primate behavior and socio- and
eco-endocrinology. She integrates fieldwork in Madagascar with hormone
assay development in the laboratory to understand how species mitigate
environmental challenges, with a current emphasis on the evolution of primate allomaternal care. More information on her research can be found at the
following Web sites:
http://www.stecot.weebly.com,
http://anthropology.arizona.edu/user/stacey-tecot,
http://www.leep.arizona.edu

ANDREA L. BADEN SHORT BIOGRAPHY
Andrea L. Baden, PhD is an Assistant Professor at Hunter College, City
University of New York and Director of Hunter’s Primate Molecular Ecology
Lab. She is a biological anthropologist with training in primate behavior
and molecular ecology. Her research integrates traditional fieldwork in
Madagascar and molecular genetic techniques to answer larger evolutionary questions regarding primate social and reproductive strategies,
with a current emphasis on the evolution of primate allomaternal care.
More information on her research can be found at the following Web sites:
http://andra581.wix.com/andreabaden, http://www.nycep.org/faculty/
andrea-baden

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Primate Allomaternal Care
STACEY TECOT and ANDREA L. BADEN

Abstract
Allomaternal care (AMC) (i.e., infant care that is provided by group members
other than an infant’s mother) is a rare, although phylogenetically widespread,
mammalian infant care strategy. In primates, however, AMC occurs at unusually
high frequencies, particularly among several haplorhine (monkey and ape) taxa.
In fact, AMC is present in every major primate radiation and has been described
in 74% of 154 species for which data are available. Its widespread presence in the
Order Primates suggests that there may have been strong selective pressure for
AMC early in primate evolution, but it is currently unknown why these behaviors
are so common in primates. Research focused on captive callitrichids (tamarins and
marmosets) has contributed greatly to our understanding of the potential causes
and consequences of highly derived forms of AMC (i.e., cooperative breeding).
Recent efforts have shifted focus to understand the selective pressures leading
to the expansion and diversification of AMC throughout the Primate Order, thus
expanding research to investigate the causes and consequences of less derived forms
of AMC. Here we review the broad-scale patterns observed in primates and outline
innovative and exciting avenues of research moving forward.

INTRODUCTION
Allomaternal care (AMC) is infant care provided by individuals other than
the genetic mother (e.g., fathers, siblings, aunts, uncles, or unrelated individuals, termed helpers), including several seemingly altruistic behaviors such as
babysitting, carrying, nursing, crèching, or huddling for thermoregulation.
Although AMC has been observed in several taxonomically diverse species
(e.g., birds, social insects, and mammals), mammalian mothers are typically
the sole providers of infant care and AMC is uncommon. However, recent
research indicates that AMC is notably abundant in primates, suggesting that
relatively strong selective pressures helped shape this behavior early in our
evolution.
AMC was the likely evolutionary antecedent to cooperative breeding—a
more derived form of AMC including infant provisioning, that evolved
in only a few species including the callitrichids (tamarins, marmosets)
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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and humans. Cooperative breeding is ubiquitous among humans, and
proposed to have been profoundly important during human evolution:
Mothers and offspring gained significant energetic benefits, enabling higher
maternal fertility, protracted infant development, and less costly brain
growth, which ultimately led to emotionally modern brains (Hrdy, 2009). It
is thought that when the cognitive abilities shared by apes and our earliest
human ancestors merged with these underlying prosocial motivations,
“shared intentionality”—a social disposition identified as the source of
many uniquely human traits, such as culture and language—emerged
(Burkart, Hrdy, & van Schaik, 2009). These traits allowed our ancestors,
and eventually modern humans, to forge deeper social relationships, and
cooperate on an unparalleled level. In short, prosocial behaviors associated
with ancestral forms of shared infant care (i.e., AMC) paved the way for us
becoming human.
FOUNDATIONAL RESEARCH
WHO CARES?
The study of primate AMC has traditionally focused on New World and Old
World monkeys. Until recently, AMC in primates was viewed as exceptional,
and thought to be entirely absent in one of the two primate suborders (strepsirrhines, i.e., lemurs, lorises, galagos). As data have accumulated, scientists
have been surprised to discover that primate AMC is both widespread and
common. Nearly 75% of primate species display some type of AMC (Table 1).
By suborder, AMC is present in 61% of strepsirrhines, and 76% of haplorhines
(monkeys, apes including humans) for which there are data.
Currently, it is difficult to make many meaningful statements about the
abundance of AMC because (i) we lack solid empirical data for many
species; (ii) estimates are heavily impacted by the number of species in the
given taxonomic group; and (iii) these broad-scale analyses do not consider
intra-specific variation. However, it is notable that AMC is present in 100%
of callitrichids (tamarins, marmosets). Perhaps even more remarkable,
because AMC was thought to be absent in strepsirrhines until just recently,
is the frequency at which AMC occurs in several of the nocturnal, solitary
and pair-living cheirogaleids (dwarf lemurs, mouse lemurs). Pair-living
males babysit (Fietz & Dausmann, 2003), and although solitary species were
once thought to have “little or no opportunity for nonmaternal care” (Ross
& MacLarnon, 2000, p. 94), ‘solitary’ females communally nest their infants
and share in allomaternal suckling (Eberle & Kappeler, 2006). It should
be noted, however, that we lack data for three of five cheirogaleid genera,
reinforcing the fact that more information is still needed. Both callitrichids

Primate Allomaternal Care

3

Table 1
Phylogenetic Distribution of Allomaternal Care in the Order Primates
N
Source

AMC

Species Strep Hap AMC
Strep Hap
excluding (%)
(%)
protection
(%)

Isler and van
98
Schaik (2012)
Hrdy (2010)
120
Tecot et al.
23
(2012, 2013)
Combined
109
dataset: Isler
and van
Schaik (2012),
Tecot et al.
(2012, 2013)
All datasets
154
combined

Carrying
Strep Hap
(%)
(%)

Notes

20

78

72.00

27
23

93
0

68.33
65.22

65.00 74.36 45.00 58.97 445 mammals
48.15 75.27 N/A N/A Primates
65.22 N/A 34.78 N/A Lemurids

78

31

71.50

64.52 74.36 48.39 58.97 —

31

123 74.03

61.29 76.42 N/A

N/A

—

Combining databases by Hrdy and Tecot (unpublished data, available in All the World’s Primates
Database), Isler and van Schaik (2012), Tecot et al. (2012), and Tecot, Baden, Romine, and Kamilar (2013).
Strep, strepsirrhines; Hap, haplorhines.

and cheirogaleids comprise several litter-bearing species for which helpers
alleviate maternal energetic burden and increase infant survival (Bales,
Baker, Miller, & Tardif, 2000; Fietz & Dausmann, 2003). Despite the fact that
the majority of the remaining primates bear singletons, AMC by fathers,
other relatives, and unrelated individuals occurs throughout the Order.
AMC by adult males is generally strongest in species where paternity is
certain. Male care is most common among pair-living taxa, including at least
two lemur species (mongoose lemurs, red-bellied lemurs; Figure 1), several
New World monkeys (tamarins, marmosets, titis, owl monkeys), and some
apes (siamangs, humans). In cases where females are not monopolizable and
males can maximize their reproductive success by living with a pair-mate
rather than seeking out multiple females, the benefits of paternal care are
clear. However, even resident males who are unrelated to the mother and
infant will sometimes provide care to extra-pair young (fat-tailed dwarf
lemurs, Fietz et al., 2000).
In group-living species with AMC, some adult males also provide infant
care, and not necessarily more often to their own genetic offspring (Ménard
et al., 2001). More often, nulliparous females (i.e., females who have not borne
offspring) provide care. Juvenile helpers of both sexes are generally older

4

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Figure 1 Red-bellied lemur (Eulemur rubriventer) male carrying an infant while
traveling in Vatoharanana, Ranomafana National Park, Madagascar. Source:
Photo credit Lahitsara Jean Pierre.

siblings, but help is not always directed towards relatives (Fairbanks, 1990),
and cannot be explained entirely by kin selection. Although AMC among
adult females is most common in female bonded species (i.e., those with little
female emigration and high female relatedness), allomothering also occurs
in species in which both sexes emigrate (capped langurs, Stanford, 1992),
although to a much lesser degree (Bennett & Davies, 1994). Despite this, AMC
is never prevalent in species characterized by male philopatry (i.e., where
males remain in their natal groups), except perhaps in anomalous cases of
maternal death.

Primate Allomaternal Care

5

WHY HELP? ADAPTIVE VALUE OF AMC
Traditionally, studies of AMC have focused on the benefits to caregivers
because helping and cooperation seemed paradoxical in light of evolutionary theory: Why should fathers invest in one infant when they can
produce several progeny by mating with additional females? Why should
individuals invest in infants who are not their own, sometimes foregoing
their own reproduction to do so? While several forms of AMC may not be
costly (e.g., huddling with infants for thermoregulation), contributing time
and energy to infants can be (Heinsohn & Legge, 1999). Babysitters can
suffer drastic reductions in body mass by sacrificing time normally allocated
to foraging and feeding (Clutton-Brock et al., 1998), carrying infants makes
travel more energetically expensive and awkward (Altmann & Samuels,
1992), and in extreme cases, one’s own reproduction may be suppressed
(Solomon & French, 1997). Despite the associated costs of AMC, studies
have revealed that helpers can gain direct benefits by, for example, learning to parent and subsequently increasing their own offspring’s survival
(vervet monkeys, Fairbanks, 1990), or by securing an infrequently available
breeding position (marmosets, Abbott, Digby, & Saltzman, 2009). They can
also benefit indirectly by providing care to related offspring and increasing
their inclusive fitness (Briga, Pen, & Wright, 2012; Hamilton, 1964), and
even by caring for unrelated individuals via mutualism (black-and-white
ruffed lemurs, Baden, Wright, Louis, & Bradley 2013), or reciprocal altruism
(capuchins, O’Brien & Robinson, 1991). Thus, AMC may represent an
optimal reproductive strategy, yielding relatively higher fitness pay-offs to
caregivers than alternative scenarios.
WHAT ABOUT MOTHERS? ADAPTIVE VALUE TO MOTHERS AND THEIR OFFSPRING
Many primate females are “continuous care and contact” mothers (Hrdy,
2009), who prohibit others from interacting with their offspring, presumably
because of potential threats such as negative infant handling and infanticide that can severely and directly impact infant survival. But mothers who
allow others to help them rear their young can benefit in dramatic ways. In
cooperative breeders, relatively greater AMC can increase an infant’s quality of care, health, and survival, and a mother’s reproductive rate (humans,
Egeland & Hiester, 1995; Sear, Mace, & McGregor, 2000; callitrichids, Bales
et al., 2000). Broad, comparative analyses determined that haplorhine mothers receiving help reproduce faster than mothers without help and may ultimately experience relatively higher reproductive success (Mitani & Watts,
1997). However, these effects on fertility are absent in lemurids (Tecot et al.,
2012) and nonprimate mammals (Isler & van Schaik, 2012). These divergent
results may indicate distinctive selective pressures for haplorhines, or reflect

6

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

the very strong influence of callitrichids on these analyses. As cooperative
breeders, litter-bearing callitrichids have a highly derived form of AMC that
includes infant provisioning, and that potentially allows offspring to grow
quickly and at less of an energetic cost to mothers, who often resume cycling
soon after birth. It appears that this extensive form of AMC largely drove
the positive relationship between AMC and fertility in haplorhines (Isler &
van Schaik, 2012). At the same time, fetal and infant growth rates for strepsirrhines are only available from provisioned, captive animals, which may
result in overestimated growth rates in species lacking AMC. Data on more
taxa will help determine whether these relationships hold true for noncooperatively breeding haplorhines, and whether the benefits to strepsirrhines
have been underestimated.
Additional hypotheses for the evolution of AMC in primates have been
tested using broad-scale comparative analyses, but caution should be used
in interpreting such studies. Comparative meta-analyses fail to consider
inter-individual variation and/or the fluctuating selection pressures at the
intraspecific level under which primate sociality has evolved (Strier, 2009).
Therefore, they may not provide the level of resolution needed to determine
the adaptive benefits of AMC in species where individual care is facultative
(i.e., can but does not always occur), or the selective pressures leading to
the expression of AMC. For example, in testing whether maternal energetic
stress favors the evolution of AMC (owing to energetic savings afforded
mothers), Ross and MacLarnon (2000) were limited in using species dietary
categories as proxies for nutritional stress. Because species have evolved
adaptations to successfully extract nutrients from their dietary items, an
ideal test of the relationships between energetic stress and AMC might be
one that is conducted among species sharing a dietary guild. Individual-level
investigations within a single species might be most informative in helping
to address what internal states and social and physical environments select
for AMC, and whether and how the quality and quantity of AMC influences
reproductive success (Mitani & Watts, 1997).
PROXIMATE MECHANISMS PROMOTING AMC
Individual variation can help identify environmental pressures selecting
for and prohibiting AMC. Maternal size, litter size, and group size are all
associated with variation in AMC (Bales, French, & Dietz, 2002), indicating
that AMC can release individuals from certain reproductive constraints. It is
also possible that energetic need drives maternal tolerance of AMC (Ross &
MacLarnon, 2000), such that lower-ranking mothers, mothers bearing twins,
or mothers with older dependent offspring would allow AMC to a greater

Primate Allomaternal Care

7

extent than higher-ranking mothers, mothers bearing singletons, or mothers
who recently gave birth.
There is growing consensus that the physiological mechanisms promoting
and maintaining maternal care may also facilitate AMC (Ziegler, 2000).
Mothers undergo critical endocrine changes during pregnancy and lactation
that have evolved to enhance responsiveness to offspring (Saltzman &
Maestripieri, 2011). More recently, research examining the endocrinological
profiles of fathers found that they respond to their mate’s pregnancy (Ziegler,
Washabaugh, & Snowdon, 2004) and to infants themselves, indicating that
paternal hormonal changes can facilitate, maintain, or prime individuals
for care. For example, there is abundant support for an inverse relationship
between paternal care and testosterone, which may decrease the likelihood
of infant-directed aggression, or reflect the trade-off between mating and
parenting effort (Wingfield, Hegner, Dufty, & Ball, 1990). In humans, paternal testosterone decreases pre- to postpartum (Storey, Delahunty, McKay,
Walsh, & Wilhelm, 2006), and after mating and siring offspring (Gettler,
McDade, Feranil, & Kuzawa, 2011). Testosterone levels decrease once males
become fathers, and are lower in those who invest more (Gettler et al.,
2011; Nunes, Fite, Patera, & French, 2001). The neuropeptide prolactin has
several hundred biological actions, including stimulating female lactation,
inhibiting male sexual behavior, and mediating parental behavior (Freeman,
Kanyicska, Lerant, & Nagy, 2000). This hormone also responds to carrying/
infant contact (cotton-top tamarins, common marmosets, Ziegler, 2000),
infant cries, and play (humans, Fleming, Corter, Stallings, & Steiner, 2002)
in fathers. Ziegler, Prudom, Zahed, Parlow, and Wegner (2009) found that
prolactin elevations even buffered experienced fathers from weight loss
associated with infant carrying, thus reducing energetic costs.
To our knowledge, very little research has examined the hormonal mechanisms underlying AMC in nonparental helpers (i.e., alloparental care),
although help from these individuals is hypothesized to be essential (Hrdy,
2009). Higher levels of vasopressin (which promotes offspring care) in
grandmothers than control women (Gray & Samms-Vaughan, 2009), and
elevated prolactin levels in cooperatively breeding nonprimate babysitters
that are otherwise absent in nonhelpers (meerkats, Carlson et al., 2006)
suggest that alloparental care also can have a hormonal basis. Variation
in hormone levels can thus help explain variation in AMC, although this
research is still in its infancy, particularly as it pertains to free-living individuals. Extending this research to nonparental helpers would provide a
critical test of the importance of hormonal mechanisms for the expression of
infant care. It is also essential to understand how different individuals have
been shaped by natural selection to help, not only in nonhuman primates,
but also in our own evolutionary history.

8

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Because the observation that AMC is widespread in primates occurred
recently, a disparity of appropriate models has resulted in a research focus
on a very limited set of primate species: the callitrichids. Two species in
particular (Callithrix jacchus, Saguinus oedipus) have contributed the vast
majority of what we know of primate hormones facilitating AMC. Therefore,
we still know very little about the role that hormones play in the expression
of AMC in the majority of species. One recent study by Rafacz, Margulis,
and Santymire (2012) of bi-parental and exclusively maternal hylobatids
(siamangs and gibbons, respectively) suggests that the same mechanisms
are at work in species with less specialized paternal care. Future research on
these mechanisms in species with facultative AMC will be fundamental in
determining how adaptable (and critical) these systems are, and whether all
primate AMC is rooted in such adaptability.
CUTTING EDGE RESEARCH
Outside of studies with humans, the bulk of the work described herein has
been conducted in captivity, largely owing to the fact that, until relatively
recently, noninvasive hormonal sampling was difficult, if not impossible
(Ziegler & Wittwer, 2005). Experimental studies have been particularly
influential on contemporary studies of hormone-behavior relationships.
They identified several hormones of interest, partly through selectively
blocking their expression and observing effects on behavior, or injecting
exogenous hormone, and were at times able to determine cause and effect. It
is now well recognized that fecal metabolites can provide reliable measures
of steroids such as cortisol and androgens, they parallel serum levels, and
have been used in numerous studies as long-term (i.e., not acute) measures
of adrenal and gonadal axis activity (Tecot, 2013). Recent work indicates that
not only steroids, but also oxytocin and vasopressin, bonding hormones of
potential interest in AMC research, and prolactin can be measured reliably
in urine (Seltzer & Ziegler, 2007; Soltis, Wegner, & Newman, 2005). Armed
with the ability to make predictions about hormones and the expression of
AMC in variable social and mating structures, and the logistical feasibility
of extracting these hormones from noninvasively collected samples, we can
now investigate the mechanisms involved in facilitating and maintaining
AMC in the natural environments in which they evolved.
Recent work in the field of behavioral genetics has revealed that variation
in behavioral style (i.e., personality) can be explained, in part, by variation
at the genotypic level (Bradley & Lawler, 2011), opening new and exciting avenues of inquiry. Although few investigations have examined the
genetic basis of parental care in primates, parental effort does appear to
have a significant heritable component in other animals (Komdeur, 2006).

Primate Allomaternal Care

9

For example, variation in the arginine vasopressin 1a gene (AVPR1a) in
prairie voles has been linked to the quality and quantity of paternal care
(Hammock & Young, 2005). Although evidence from field studies are more
tenuous (Ophir, Campbell, Hanna, & Phelps, 2008; Solomon et al., 2009),
together, captive and wild-based studies provide strong evidence indicating
the importance of this gene region in mediating social behavior (Fink,
Excoffier, & Heckel, 2006; Heckel & Fink, 2008).
In humans, AVPR1a variants have been linked to altruistic tendencies
(Israel et al., 2008) and the propensity for men to form long-term, content partnerships (Walum et al., 2008). Recent surveys have identified significant intraand interspecific AVPR1a sequence variation across nearly all major primate
radiations (Anestis et al., 2014; Babb, Fernandez-Duque, & Schurr, 2010;
Hong et al., 2009; Rosso, Keller, Kaessmann, & Hammond, 2008) but to date,
researchers have been unable to link this variation to either social or mating
system in primates (Hong et al., 2009). However, recent studies have found
links between microsatellite polymorphisms (i.e., repeating sequences of
DNA) and various personality traits, including conscientiousness (Hopkins,
Donaldson, & Young, 2012) and friendliness (Anestis et al., 2014).
Although most work has focused on AVPR1a, several other promising
candidate genes have also been linked to parental behavior. For example,
more than 30 single nucleotide polymorphisms (i.e., DNA sequence variation occurring when a single nucleotide—A, T, C or G—differs among
members of a population) are known in the OXTR gene region (Israel et al.,
2008). OXTR gene polymorphisms have been associated with several social
behaviors, including empathy (Rodrigues, Saslow, Garcia, John, & Keltner,
2009), prosociality (Kogan et al., 2011), and both maternal (Francis, Young,
Meaney, & Insel, 2002) and paternal sensitivity (Bakermans-Kranenburg &
van Ijzendoorn, 2008). While results from captive studies are intriguing,
little if any work has focused on the links between OXTR variation and
personality in the wild.
KEY ISSUES FOR FUTURE RESEARCH
Work in the last 4 years has substantially increased our understanding of how
widespread AMC is, thus increasing (i) the power of comparative analyses,
(ii) our ability to look for broad patterns of selection, and (iii) the availability
of suitable species of study. However, we still lack complete data on the distribution of primate AMC, which can skew comparative analyses. We therefore
encourage researchers to broaden their taxonomic focus and also report AMC
behaviors whenever possible (and noting its absence in cases where AMC is

10

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

never observed). Furthermore, armed with increasingly sophisticated technologies, researchers can begin to address not only the AMC behaviors themselves, but also the endocrinological, molecular, and energetic underpinnings
of AMC.
Finally, It is important to consider the delicate balance between generating
high-resolution data (i.e., frequent, high intensity sampling) and large
sample size (i.e., many individuals from several social groups). While
studies of some species can easily meet both criteria (e.g., cercopithecids),
many other species live in strikingly smaller social groups, particularly the
strepsirrhines. Researchers are thus faced with the difficult trade-off between
achieving fine-grained behavioral resolution and statistical power. This issue
is further compounded in species with facultative AMC. This does not mean
that studies aren’t worthwhile. In these cases, collecting high-resolution data
from a relatively small, hopefully representative sample of focal individuals
is preferable to neglecting to study taxa at all.
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(pp. 185–195). Springer: New York, NY.
Tecot, S., Baden, A., Romine, N., & Kamilar, J. (2012). Infant parking and nesting, not
allomaternal care, influence Malagasy primate life histories. Behavioral Ecology and
Sociobiology, 66, 1375–1386.
Walum, H., Westberg, L., Henningsson, S., Neiderhiser, J., Reiss, D., Igl, W., … ,
Lichtenstein, P. (2008). Genetic variation in the vasopressin receptor 1a gene
(AVPR1A) associates with pair-bonding behavior in humans. Proceedings of the
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Theoretical implications for patterns of testosterone secretion, mating systems,
and breeding strategies. American Naturalist, 136, 829–846.
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improved methods for storage, transport, processing, and analysis. American Journal of Primatology, 67, 159–174.
Ziegler, T., Washabaugh, K., & Snowdon, C. (2004). Responsiveness of expectant
male cotton-top tamarins to mate’s pregnancy. Hormones and Behavior, 45, 84–92.

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

Ziegler, T., Prudom, S., Zahed, S., Parlow, A., & Wegner, F. (2009). Prolactin’s mediative role in male parenting in parentally experienced marmosets (Callithrix jacchus). Hormones and Behavior, 56, 436–443.

FURTHER READING
Chism, J. (2000). Allocare patterns among cercopithecines. Folia Primatologica, 71,
55–66.
Donaldson, Z., & Young, L. (2008). Oxytocin, vasopressin, and the neurogenetics of
sociality. Science, 322, 900–904.
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Krebs & N. B. Davies (Eds.), Behavioural ecology: An evolutionary approach (3rd ed.,
pp. 301–335). Oxford, England: Blackwell Scientific.
Fernandez-Duque, E., Valeggia, C., & Mendoza, S. (2009). The biology of paternal care in human and nonhuman primates. Annual Review of Anthropology, 38,
115–130.
Hrdy, S. (2009). Mothers and others: The evolutionary origins of mutual understanding.
Cambridge, MA: Belknap Press of Harvard University Press.
Isler, K., & van Schaik, C. (2012). Allomaternal care, life history and brain size evolution in mammals. Journal of Human Evolution, 63, 52–63.
Israel, S., Lerer, E., Shalev, I., Uzefovsky, F., Reibold, M., Bachner-Melman, R., … ,
Ebstein, R. (2008). Molecular genetic studies of the arginine vasopressin 1a receptor (AVPR1a) and the oxytocin receptor (OXTR) in human behavior: From autism
to altruism with some notes in between. Progress in Brain Research, 170, 435–449.
Ross, C. (2003). Life history, infant care strategies, and brain size in primates. In P. M.
Kappeler & M. E. Pereira (Eds.), Primate life histories and socioecology (pp. 266–284).
Chicago, IL: University of Chicago Press.
Ross, C., & MacLarnon, A. (2000). The evolution of non-maternal care in anthropoid
primates: A test of the hypotheses. Folia Primatologica, 71, 93–113.
Tecot, S., Baden, A., Romine, N., & Kamilar, J. (2013). Reproductive strategies and
infant care in the Malagasy primates. In K. Clancy, K. Hinde & J. Rutherford (Eds.),
Building babies: Primate development in proximate and ultimate perspective. Developments in primatology: Progress and prospects (pp. 321–359). New York, NY:
Springer.
Whitten, P., Brockman, D., & Stavisky, R. (1998). Recent advances in noninvasive
techniques to monitor hormone-behavior interactions. Yearbook of Physical Anthropology, 27(Suppl.), 1–23.
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mammalian and avian studies. Folia Primatologica, 71, 6–21.

STACEY TECOT SHORT BIOGRAPHY
Stacey Tecot, PhD is an Assistant Professor at the University of Arizona,
the Director of the Laboratory for the Evolutionary Endocrinology of Primates, and co-director of the Ranomafana Red-Bellied Lemur Project. She is

Primate Allomaternal Care

15

a biological anthropologist with training in primate behavior and socio- and
eco-endocrinology. She integrates fieldwork in Madagascar with hormone
assay development in the laboratory to understand how species mitigate
environmental challenges, with a current emphasis on the evolution of primate allomaternal care. More information on her research can be found at the
following Web sites:
http://www.stecot.weebly.com,
http://anthropology.arizona.edu/user/stacey-tecot,
http://www.leep.arizona.edu

ANDREA L. BADEN SHORT BIOGRAPHY
Andrea L. Baden, PhD is an Assistant Professor at Hunter College, City
University of New York and Director of Hunter’s Primate Molecular Ecology
Lab. She is a biological anthropologist with training in primate behavior
and molecular ecology. Her research integrates traditional fieldwork in
Madagascar and molecular genetic techniques to answer larger evolutionary questions regarding primate social and reproductive strategies,
with a current emphasis on the evolution of primate allomaternal care.
More information on her research can be found at the following Web sites:
http://andra581.wix.com/andreabaden, http://www.nycep.org/faculty/
andrea-baden

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