Amanda Tan is a PhD candidate at Nanyang Technological University in Singapore. She was awarded a Leakey Foundation research grant in the spring of 2013. Here is a summary of her team's recent paper in PLOS ONE.

Researchers Catalog Variation in Stone-Tool Use by Burmese Long-Tailed Macaques

Burmese long-tailed macaques living on islands in southern Thailand use 17 different action patterns in their use of stone tools to crack open seafood.

Since 2007, a group of researchers including Leakey Foundation grantee, Amanda Tan, has been documenting variation in the tools and action patterns used by a population of coastal-living Burmese long-tailed macaques in southern Thailand, under an 8-year field project led by Michael D Gumert from the Nanyang Technological University, Singapore. These macaques use stone and shell tools to crack open a wide variety of marine bivalves, gastropods, and crustaceans, as well as plant seeds. Their findings are described in the journal PLOS ONE

To identify variation in how the macaques used tools, the researchers collected and analyzed videos of over 600 instances of tool use from 90 macaques in populations on Piak Nam Yai and Thao Islands, in Laem Son National Park Thailand. They found that the macaques used different parts of stone and shell tools: the flatter faces and edges, and the sharp points. They then catalogued a total of 17 different action patterns in macaque tool use, which varied in hand use, posture, and striking motions. They also observed over 100 macaques on Piak Nam Yai Island’s costs at over 3000 time points to determine what proportion of the population used each action pattern, and how often.

They found that 80% of the macaques used tools, each using between one and four different action patterns. Most commonly, the macaques used one-handed hammering with the points of smaller tools to crack open oysters that grew on rocks, and used one- or two-handed hammering with the faces and edges of larger tools to crack unattached shellfish that had to first be placed on anvils. Some of the macaques however, used rare or idiosyncratic action patterns. All action patterns can be viewed in a video published with the article, and on PLOS’s Youtube channel.

Burmese long-tailed macaques are the most recent addition to the small group of nonhuman primates known to use stone tools in the wild, which had previously comprised of only some populations of West African chimpanzees, and robust capuchins of South America. Compared to the nut cracking behaviour of capuchins and chimpanzees, there seems to be much greater variation in the use of different tool surfaces and striking actions in the use of stone tools by macaques.

At least some of the variation is due to the unique food types that these macaques process with stones. Macaques are the only species to regularly process oysters that grow on rocks, and these oysters require different processing techniques from the nuts that are cracked by chimpanzees and capuchins. Since oysters cannot be moved and placed on flat anvils, the macaques must chip them open with precision from different striking angles depending on the surface on which the oyster grows. As a result, the macaques have developed axe hammering, or using the sharp points of stones to chip open food items, which has not been observed in other species.

Cataloging the tools and actions involved in macaque tool use thus raises new questions about tool technologies and cultures in the primate lineage that can be explored with future study. By answering questions about how different action patterns develop and are influenced by environmental constraints and learning processes, we can gain a better understanding of how technology and culture evolves in species living in different environments, with different social systems.

Click here to read the journal article on PLOS ONE.






AuthorH Gregory

Marina Davila-Ross was awarded a grant from The Leakey Foundation in the spring of 2015 for her research project entitled "Systematically testing facial thermal imaging as a most sensitive and reliable novel technology to directly compare subtle emotion changes in apes and humans." Her work on facial expressions and laughter in chimpanzees was recently published in the journal PLOS ONE.

Chimpanzee facial expressions, vocalizations used differently during play

Chimpanzees may be able to use facial expressions and vocalizations flexibly, notably during physical contact play, according to a study published June 10, 2015 in the open-access journal PLOS ONE by Leakey Foundation grantee, Marina Davila-Ross from the University of Portsmouth, UK and colleagues.

Open mouth expressions of silent and audible laughter in chimpanzees and humans. Image from PLOS ONE paper. Davila-Ross et. al.

Open mouth expressions of silent and audible laughter in chimpanzees and humans. Image from PLOS ONE paper. Davila-Ross et. al.

The ability to flexibly produce facial expressions and vocalizations has a strong impact on the way humans communicate, but scientists' understanding of nonhuman primate facial expressions and vocalizations is limited. The authors of this study investigated whether chimpanzees produce the same types of facial expressions with and without accompanying vocalizations, as do humans. Forty-six chimpanzees were video-recorded during spontaneous play at the Chimfunshi Wildlife Orphanage, Zambia. ChimpFACS, a standardized coding system, was applied to measure chimpanzee facial movements, based on Facial Action Coding System (FACS) developed for humans.

Data showed that chimpanzees produced the same fourteen open-mouthed facial expressions when laugh sounds were present as when they weren't. Based on the data, the authors suggest that chimpanzees produce these facial expressions flexibly, without being constrained by the accompanying vocalizations. Furthermore, the data indicated that the facial expression in addition to vocalization, as well as the facial expression alone, were used differently in social play, for instance, when in physical contact with playmates and when matching playmates' open-mouthed faces. These findings support the idea that chimpanzees produce distinctive facial expressions independently from a vocalization, and that their use affects communicative meaning, as both traits are important for a more explicit and versatile way of communicating.

Click here to read the paper on PLOS ONE.

Citation: Davila-Ross M, Jesus G, Osborne J, Bard KA (2015) Chimpanzees (Pan troglodytes) Produce the Same Types of 'Laugh Faces' when They Emit Laughter and when They Are Silent.PLoS ONE 10(6): e0127337. doi:10.1371/journal.pone.0127337


AuthorMeredith Johnson

The deadline approaches! Those interested in applying for a research grant during our Fall 2013 cycle must complete the application by July 15th. Our website is your source for guidelines for applying as well as the place to start the application process.

We received over one hundred applications for the Spring 2013 cycle, and we expect a similar number for Fall 2013. Here are a few suggestions to help your application stand out from the others and maximize your chances for funding:

‣ Present a clear correlation to human origins. We fund research into human origins, including paleoanthropology of the Miocene, Pliocene and Pleistocene; primate behavior; and the behavioral ecology of contemporary hunter-gatherers. Other areas of study are generally not considered.

‣ State your hypotheses clearly with ways and means of testing them.

‣ Review and accurately cite related literature thoroughly.

‣ Submit a tight budget (Do a lot with a little). Find out from other researchers what they have spent on lodging, food, and transportation in your study area.

We understand you may have questions about the application process, so we've included a few frequently asked questions here: Q: I've received a previous award from The Leakey Foundation. Am I eligible for another? A: Yes, as long as you are fully compliant with the terms of your previous award. You may email us at to find out what, if any, requirements are outstanding.

Q: Does the Foundation offer scholarships for undergraduate and graduate studies? A: No, Foundation grants are limited to funding for expenses directly related to research projects. Eligible applicants must either hold a PhD or equivalent qualification in anthropology (or a related discipline) or be enrolled in a doctoral program with all degree requirements fulfilled other than the thesis/dissertation.

Q: If I'm not affiliated with a school or research institution, may I apply for a grant? A: No, we do not award directly to individuals.

For a complete listing of frequently asked questions, please click here, and if you have further questions concerning the application process, feel free to contact us at

AuthorBeth Green

Q: How did you first come to study human origins?

A: During my first semester [of college], I participated in a program in which a small group of freshmen took several classes around one interdisciplinary theme. Knowing that I was interested in science, I chose the one science-oriented theme available at the time – evolution. I had learned next-to-nothing about evolution in high school, and was fascinated with the explanatory power of evolutionary theory.

Q: Once you learned more about evolutionary theory, how did you decide upon a focused area of research?

A: I realized that I loved studying primates in the field and wanted to continue to do so. In order to gain the experience I needed to conduct research in such settings, I took a field position with the Kakamega Monkey Project in Kenya where I managed a team of international and local field assistants. A year later, I entered the graduate program at Columbia and began my doctoral research at the same fieldsite.

Q: What will this grant form The Leakey Foundation help you research and better understand about primates and our own evolution?

A: Sociality is a hallmark of the primate order. The relationship between social and mating systems is an unending source of questions in evolutionary biology. There is an integral connection between social and mating systems, as how individuals are distributed in the environment depends primarily on their strategies for maximizing reproduction. With this research, I want to evaluate the effect of intrasexual competition on male reproduction in primates living in one-male groups.

This project focuses on wild blue monkeys which live in one-male social groups, but in which preliminary genetic evidence suggests (1) a surprising lack of resident male reproductive monopoly and (2) high inter-annual variability in resident and non-resident (i.e. bachelor) male reproductive output.

Male mammals compete with each other for access to fertile females. When animals live in one-male/multi-female groups, the single resident male should have a reproductive advantage over non-residents (i.e. bachelors).

I will investigate this assumption by extracting DNA from fecal samples [which I will non-invasively collect] and assigning paternity to approximately 140 infants born over a ten-year period. Quantifying reproduction by resident and bachelor males will allow me to determine the relative success of reproductive strategies.

I will then use long-term behavioral and demographic records to evaluate how variables including the number of reproductive opportunities, the number of competitor males, dominance rank, and body size affect resident and bachelor reproduction. This model will clarify the relationship between social and mating systems and thereby allow us to better infer patterns of sociality and reproduction in both extant and extinct taxa, including human ancestors.

AuthorBeth Green


2012 Spring Grants Report

Scientists are turning to The Leakey Foundation for funding now more than ever.

During the most recent grants cycle, Spring 2012, we received a record number of applications (the highest number in 44 years). The competition was stiff, and the funding decisions were even more difficult than usual. Here is a breakdown of some statistics for the cycle.

AuthorBeth Green


The Female In Evolution Symposium is now sold out!

Live online streaming

Not in San Francisco? We are very pleased to announce The Female In Evolution Symposium will be streamed live online via For more information and details on how to register for live streaming, please visit the special event page.

Full Schedule, Lecture Abstracts and Speaker Biographies

Saturday, April 28, 2012

at the California Academy of Sciences.

Greeting from the California Academy of Sciences

9:00 AM

Dr. Terry Gosliner, Dean of Science and Research Collections

Symposium Introduction

Dr. Kelly Stewart


9:15 AM

“The Real Females of Human Evolution” by Dr. Adrienne Zihlman

Paleoanthropology Session

10:00 AM


Dr. Leslea Hlusko

Overview Lecture

10:10 AM

“Millions of Years of Moms” by Dr. Daniel Lieberman

Case Study

10:40 AM

“The Role of Prehistoric Mothers in the Evolution of Language” by Dr. Dean Falk


Leslea Hlusko, Daniel Lieberman, and Dean Falk

Behavioral Session

11:30 AM


Dr. Jill Pruetz

Overview Lecture

11:40 AM

“The Natural History of Social Bonds” by Dr. Joan Silk

Case Study

“Primate Social Cognition” by Dr. Dorothy Cheney


12:10 PM

Jill Pruetz, Joan Silk and Dorothy Cheney


1 PM to 1:45 PM

Afternoon Keynote

1:45 PM

“The Evolution of Mothering: How Long Should A Mother Suckle Her Baby?” by Dr. Robert Martin

Hunter/Forager Session

2:20 PM


Dr. Brooke Scelza

Overview Lecture

2:30 PM

“From Men’s Hunting to the Importance of Grandmothers: Lessions About Human Evolution From The Behavioral Ecology of Foragers” by Dr. Kristen Hawkes

Case Study

3:00 PM

“Beyond Woman the Gatherer: Women’s Cooperative Hunting, Sharing, and Social Networks in Aboriginal Australia” by Dr. Rebecca Bird


Brooke Scelza, Kristen Hawkes, and Rebecca Bird

Symposium Wrapup

3:45 PM

Dr. Leslie Aiello


Biographies and Abstracts

Kelly Stewart, Symposium Chairperson

University of California, Davis

Dr. Kelly Stewart is a Research Associate in the Department of Anthropology at the University of California, Davis. During her college summers, Dr. Stewart dug up fossils in northern Kenya with Richard Leakey. She later became a student of Dian Fossey, and has been observing, thinking about, and writing about gorilla behavior and conservation ever since. She is the co-author of Gorilla Society, with her husband and research partner Dr. Alexander Harcourt.



The Real Females of Human Evolution

When woman-the-gatherer was first proposed as a counter to man-the-hunter, we were only beginning to understand the many faces of primate females – their role as teachers, tool users, carriers of tradition, and as the social glue in society. In ensuing decades we have learned about the skills and talents of female primates which have been key ingredients in the evolution of our species.

Adrienne Zihlman

University of California, Santa Cruz

Adrienne Zihlman, Professor of Anthropology at the University of California, Santa Cruz, has had major impacts on the field of human evolution. Her critique of the Man-the-Hunter concept made way for understanding the role of women in evolution, an approach that has become mainstream. Her publications cover human locomotion, sexual dimorphism and growth and development. She is author of The Human Evolution Coloring Book, co-editor of The Evolving Female, and is co-authoring a book on comparative ape anatomy.



Leslea Hlusko, Session Chairperson

University of California, Berkeley

Dr. Leslea Hlusko earned her PhD from Penn State University in 2000. She is currently an Associate Professor Integrative Biology at the University of California Berkeley. Her research focuses on how genes influence skeletal variation and how this has evolved through time as seen in the fossil record, focusing on primates and human evolution. Her lab projects include gene expression studies and quantitative genetic analyses. She co-directs the Olduvai Vertebrate Paleontology Project at Olduvai Gorge, Tanzania.


Overview Lecture: Millions of Years of Moms

Natural selection was hard at work changing the human body over the last few million years, and much of that selection was driven by the challenges of being a mother. I will present a brief review of the evolution of the human female body, focusing on how natural selection helped mothers cope with the biomechanical demands of being a pregnant biped, with carrying infants and food over long distances, and with giving birth to large-brained babies.

Daniel Lieberman

Harvard University

Dr. Daniel Lieberman is a Professor of Anthropology at Harvard University and Chair of the Biological Anthropology Department, while also serving on the Curatorial Board of the Peabody Museum. Dr. Lieberman is recognized as a leading expert on morphology and is especially interested in when, how and why early hominins first became bipeds, and then became so exceptional as long distance endurance runners. He is a member of the Leakey Foundation Scientific Executive Committee.


Case Study: The Role of Prehistoric Mothers in the Evolution of Language

Clues about the emergence of protolanguage appear every day in the interactions between modern parents and their infants. Parents the world over speak to infants in a special way—known as baby talk, musical speech, or motherese, which helps them acquire their native language. This presentation considers how and why motherese may have been invented by prehistoric mothers and their infants, and the possible role of infant-directed speech in the origin of language.

Dean Falk

Florida State University

Dean Falk is an evolutionary anthropologist who splits her time between Santa Fe, New Mexico where she is a Senior Scholar at the School for Advanced Research (SAR), and Tallahassee, Florida where she is the Hale G. Smith Professor of Anthropology at Florida State University. Her work focuses on the evolution of the human brain and cognition. Recent projects include collaborative research on Homo floresiensis (“Hobbit”) and an investigation of the brain of Albert Einstein.



Jill Pruetz, Session Chairperson

Iowa State University

Dr. Jill Pruetz is the Walvoord Professor of Liberal Arts & Sciences (Anthropology) at Iowa State University. As a primatologist, Dr. Pruetz has studied the behavior of non-human primates such as chimpanzees, spider monkeys, howling monkeys, tamarins, patas monkeys, and vervets in various locales. She is interested in the influence of ecology on primate and early human feeding, ranging, and social behavior. She currently has an ongoing research project in southeastern Senegal to study chimpanzees in a habitat similar to that of early hominids.


Overview Lecture: The Natural History of Social Bonds

For female baboons close and stable social bonds are the foundation of cooperation. These relationships help females cope with stress, and also enhance their reproductive success and longevity. These findings parallel evidence that social ties have positive effects on physical and mental health in humans. And as with humans, for female baboons the strength and stability of these bonds are more important than their number.

Joan Silk

University of California, Los Angeles

Dr. Joan Silk’s research interests are wide ranging and include biological anthropology, primate behavior, and evolutionary biology. She is especially interested in how natural selection shapes social evolution in primates. Her recent focus is on social strategies of female baboons and the origins of altruistic behavior. Dr. Silk is a prolific writer, an author of over 80 publications and co-author of a biological anthropology text, How Humans Evolved. She is a member of the Leakey Foundation Scientific Executive Committee.


Case Study: Primate Social Cognition

Studies on both animals and humans have shown definitively that individuals who are able to establish strong social bonds experience better health and higher offspring survival. It seems likely that natural selection has also favored the cognitive abilities to monitor and manage social relationships. There is growing evidence that monkeys and other animals are adept at recognizing other individuals’ social relationships and dominance ranks. At the same time, there are also many fundamental differences between animal social cognition and the social cognition of humans.

Dorothy Cheney

University of Pennsylvania

Dr. Dorothy Cheney is an expert on primate social behavior, communication, cognition. In 1977, together with her husband and collaborator Robert Seyfarth, she began an 11 year field study of vervet monkeys in Kenya, which led to the publication of How Monkeys See the World. From 1992 through 2007 Dr. Cheney and Dr. Seyfarth studied baboons in the Okavango Delta of Botswana. In 2007, they published Baboon Metaphysics.


Afternoon Keynote

Evolution of Mothering: How Long Should a Mother Suckle Her Baby?

All primates have drawn-out life histories with long pregnancies and extended suckling. Time devoted to individual offspring more than compensates for limited daily investment in reproduction. A key part of intensive maternal care in primates is frequent suckling on demand, reflected in milk composition. In all these respects, humans are typical primates; but we also have special features, notably in brain development. But how long should a mother suckle her baby? Biological comparisons yield clues to the natural breastfeeding period for which women are adapted.

Dr. Robert Martin

The Field Museum

Dr. Robert Martin is A. Watson Armour III Curator of Biological Anthropology at the Field Museum in Chicago. He has devoted his career to exploring the evolutionary tree of primates, as summarized in his 1990 textbook Primate Origins. Dr. Martin is particularly interested in reproductive biology and the brain, because these systems have been of special importance in primate evolution. His research is based on broad comparisons across primates, covering reproduction, anatomy, behaviour, palaeontology and molecular evolution.



Dr. Brooke Scelza, Session Chairperson

University of California, Los Angeles

Dr. Brooke Scelza is an assistant professor at UCLA. A human behavioral ecologist, Dr. Scelza is interested in understanding the adaptive nature of behavior as a function of local socioecological context. Her research focuses mainly on questions related to reproductive decision-making and parental investment, and on understanding the social environment as a critical influence on how people negotiate life history trade-offs. She is currently conducting fieldwork with the Himba, a group of semi-nomadic pastoralists living in northwest Namibia.


Overview Lecture: From Men’s Hunting to the Importance of Grandmothers: Lessons About Human Evolution from the Behavioral Ecology of Foragers

Beginning my ethnographic work with hunter-gatherers I assumed that most distinctive human features evolved as a consequence of ancestral females pairing with hunting males to form nuclear families with men provisioning their wives and dependent offspring. Challenges to that “hunting hypothesis” have mounted in paleoanthropology and archaeology, but it was behavioral findings that forced my own paradigm shift. I’ll review some of those findings, including evidence of the important role of grandmothers, and some life history comparisons between humans and chimpanzees.

Dr. Kristen Hawkes

University of Utah

Kristen Hawkes is Distinguished Professor of Anthropology at the University of Utah. Her ethnographic projects with hunter-gatherers investigate sex and age differences in foraging strategies to improve hypotheses about human evolution. The importance of grandmothers’ help for youngsters when their mothers have newborns focused her attention on the evolution of human longevity, and prompted continuing comparisons of human and chimpanzee life history. She is a member of the National Academy of Sciences, The American Academy of Arts and Sciences, and the Scientific Executive Committee of the Leakey Foundation.


Case Study: Beyond Woman the Gatherer: Women’s Cooperative Hunting, Sharing, and Social Networks in Aboriginal Australia

Gender roles among foraging peoples are usually considered to be nearly universal: that men are hunters and women gatherers of plant foods, that men are more productive than women and that women cooperate mainly with spouses in a division of labor designed to care for dependent offspring; a pattern that is rooted in our evolutionary past. I describe an alternative perspective of women as hunters who cooperate extensively in acquiring small animals, sharing food and caring for children.

Rebecca Bliege Bird

Stanford University

Dr. Rebecca Bliege Bird is an Associate Professor of Anthropology at Stanford University. She is an ecological anthropologist interested in the socioecology of subsistence in small scale societies. Dr. Bird pursues such topics as the gender division of labor in hunting and gathering, cooperation, costly signaling, indigenous conservation/land management, and fire ecology. She’s currently involved in a long-term ethnographic and ecological research project with Martu people in Australia’s Western Desert.


Symposium Wrap Up

Dr. Leslie Aiello

Wenner-Gren Foundation

Dr. Leslie Aiello is the President of the Wenner-Gren Foundation of Anthropological Research, which is largest private foundation in existence devoted solely to the support of international anthropological research. She is evolutionary anthropologist with special interests in the evolution of human adaptation as well as in broader issues of evolutionary theory, life history and the evolution of the brain, diet, language and cognition. Previously Dr. Aeillo was head of University College London’s Anthropology Department and Graduate School. She is a former editor of the Journal of Human Evolution.

Produced in partnership with the California Academy of Sciences, this special symposium is generously sponsored by Jean and Ray Auel, Gordon Getty, and with support from Wells Fargo Bank.

AuthorBeth Green

Live Video Stream Available!

Symposium:The Female in Evolution

Saturday, April 28, 2012 A human female is born, lives her life, and dies within the span of a few decades, but the shape of her life has been strongly influenced by 50 million years of primate evolution. Join leading scientists for a special symposium, in San Francisco at the California Academy of Sciences, as they discuss the The Female in Evolution.

AuthorBeth Green
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During The Leakey Foundation 2011 Annual Auction and Dinner, Foundation Trustee Mrs. Carolyn Farris bid on and won the "naming rights" for the next chimpanzee born at the Fongoli site in Senegal. Fongoli, which is run by Leakey Grantee Jill Pruetz, is home to a unique group of chimpanzees that have adapted to living in a savanna environment, often seen by Pruetz and her team hunting bush babies with "spears". Mrs. Farris chose the name "Pistache" for the newest male chimp at Fongoli, born to Natasha sometime in April of this year.

In a letter sent to the Foundation, Mrs. Farris remarked:

"I would like to name Natasha’s baby “Pistache” (French for pistachio nut), after my long hair Chihuahua. I adopted her from the Helen Woodward Animal Center and she was named after a character in a book. The chain of events that led to her adoption started on Bastille Day, so I thought a French name would be appropriate for her. The name is pronounced Pee-stash. My little dog is popular with everyone she meets, as she is loving, cuddly and playful. She is also tall for a Chihuahua, just as Natasha and her son are tall."

You can read more about Natasha and Pistache in Dr. Pruetz's newest post on the Fongoli Chimps Blog. Once there are photos taken of Pistache, we will be sure to post them!

Above photo courtesy of Kambiz Kamrani, editor of and

AuthorBeth Green
Sarah Mathew, UCLA

Sarah Mathew, UCLA

Leakey Foundation Grantee Sarah Mathew was published in today's PNAS Early Edition.

She was awarded a research grant by The Leakey Foundation in 2009.

Her dissertation research examines how the Turkana, an acephalous pastoral society in East Africa, solve the collective action problem in warfare. She also examines the scale of cooperation and norms in Turkana warfare, to evaluate the role of cultural evolutionary processes in shaping the scale of human cooperation. The following is an abstract of and link to the article in PNAS.

Punishment sustains large-scale cooperation in prestate warfare
by Sarah Mathew, UCLA

Abstract: Understanding cooperation and punishment in small-scale societies is crucial for explaining the origins of human cooperation. We studied warfare among the Turkana, a politically uncentralized, egalitarian, nomadic pastoral society in East Africa. Based on a representative sample of 88 recent raids, we show that the Turkana sustain costly cooperation in combat at a remarkably large scale, at least in part, through punishment of free-riders. Raiding parties comprised several hundred warriors and participants are not kin or day-to-day interactants. Warriors incur substantial risk of death and produce collective benefits. Cowardice and desertions occur, and are punished by community-imposed sanctions, including collective corporal punishment and fines. Furthermore, Turkana norms governing warfare benefit the ethnolinguistic group, a population of a half-million people, at the expense of smaller social groupings. These results challenge current views that punishment is unimportant in small-scale societies and that human cooperation evolved in small groups of kin and familiar individuals. Instead, these results suggest that cooperation at the larger scale of ethnolinguistic units enforced by third-party sanctions could have a deep evolutionary history in the human species.

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1105604108

Several articles were written on this paper, follow links below:

It is human nature to cooperate with strangers - NewScientist

Band of brothers at war - Discover Magazine

Study of East African group suggests punishment could sustain large-scale cooperation among strangers -

Helping out strangers is hard-wired into human nature -

AuthorBeth Green

This is the fourth in a series of posts about Sosthene Habumuremyi's dissertation research on the hormonal correlations of socio-sexual behaviors in female mountain gorillas.

Sosthene's research project combines behavioral data collected in the field with hormonal data analyzed in the lab. The results of this study will characterize the specific behavioral patterns around the time of ovulation in Mountain Gorillas; specifically mating behavior, patterns of mating solicitations, and any evidence of coercion (aggression) by the silverbacks directed towards the females.

We asked Sosthene a series of questions about his work and here are some of his responses.

Sosthene in the field.

Sosthene in the field.

Q. Do you prefer working in the field or the lab? Please explain.

A. I prefer to work in the field because each day is different! I experience difficult and easy times which are both useful and part of the job! Mountain gorillas are exceptional primates which show many varieties in their way of living. When I am with them, I see more than I'm expecting to see. So, it is important for me to appreciate how our field protocol is still working and progressing; being in the field helps a lot with monitoring the project and profiling (in my mind) the potential findings. Besides, the field work is for me an opportunity to get an exact image of the work done in biodiversity conservation. As a researcher, it is an excellent occasion to bring a personal perspective.

I can not say that I do not like the lab, as our field data will be deciphered with the lab results! This combination of field work and lab analysis is the strength of this project.

Q. Is there one question from your list of research questions that you are most excited to find the answer? Can answering that question tell humans something about themselves?

A. It's difficult for me to choose one question that I'll be excited to answer! I'm really interested to find answers for all of our research questions. Those findings will raise certainly some curiosities in human reproduction biology. For example humans should be interested in knowing: what hormonal profiles exist during the conception in young and adult women; how this evolved from the common ancestor of primates; and what are normal profiles corresponding to critical fertility periods.

Q. Tell us about some interesting behavior you have witnessed by the gorillas while in the field.

A. The most impressive moment of my field work was the last week of October 2010 when the three silverbacks from Kuryama's group were competing rashly for access to the females. Kuryama is a dynamic group of 15 individuals: Kuryama (chief, 24 years old), Kirahure (19 years old) and Vuba (17 years old) are all very large silverbacks! (They were also all born in the month of August.) The 3 suffered serious injuries due to the intra-group fights. We were thinking that Kuryama was loosing the dominance in the group, as he was aggressed by Kirahure, and even by the young Vuba. All of this behavior began when I was collecting behavioral data on a cycling female called Mahirwe.

She successfully solicited copulation to Kirahure, and after, Kirahure followed Mahirwe displaying incessantly. In one hour, I recorded 12 displays of Kirahure toward Mahirwe! At a certain time, Mahirwe climbed a tree, and Kirahure waited for her until she came down the tree! He went on following her, displaying and soliciting copulation...however, unsuccessfully!

From this day, me and other researchers recorded lots of aggressive behavior between those three males, and in addition when one silverback tried to solicit copulation to a favorite female of another male. In mountain gorilla groups, while females are rivaling for food and protection, males are actually challenging for access to the females!

Q. Are you noticing different results, trends or date between the nine social groups? Is one group of females more successful with producing offspring? Is one group less fertile?

A. There's no clear difference in key-behavioral data from the target groups that we're sampling. We will wait for statistical analysis to confirm or reveal what we can not be able to perceive now. However, we're seeing that the small groups are growing and that one-male groups are well reproductively managed.

Q. Are there data, trends or conclusions you can share with the general audience?

A. Many conclusions will emerge after the lab analysis. But, we can say that reproductive behaviors are not restricted only in fertile window in mountain gorillas as it is the case in humans.


AuthorBeth Green

Sosthene's research project combines behavioral data collected in the field with hormonal data analyzed in the lab. The results of this study will characterize the specific behavioral patterns around the time of ovulation in mountain gorillas; specifically mating behavior, patterns of mating solicitations, and any evidence of coercion (aggression) by the silverbacks directed towards the females.

Sosthene (center) with research assistants. 

Sosthene (center) with research assistants. 

We asked Sosthene a series of questions about his work and here are some of his responses. In a few days we will post another round of Q and A with Sosthene.

Q. How do you identify the gorillas in your group?

A. Some primates, like gorillas can be identified by their faces. In particular, mountain gorillas can be recognized and named individually by looking at their nose-prints! Each of the 480 mountain gorillas found in the Virungas has a different nose print, similar to human fingerprints!

In some cases, experienced trackers help with rapid identification because nose-prints are not always visible. We use additional tips like the gorillas' group; the group/lone individuals' home range; the body size; the status and darkness of hair; the other mountain gorilla individuals found often in proximity (for example: individuals from the same mother, infants or a favorite female around the dominant silverback).

Other ways for identification include abnormal gestures (for example: Gutangara, a female from Pablo's group, is always nudging her left shoulder); and also malformations (for example: Umwana, a female from Inshuti's group has a straightened finger).


Q. Are there any former poachers working as Karisoke field assistants now? How does this transition work?

A. Recruiting former poachers was among the initial strategies to get effective information on illegal activities in the National Park of Volcanoes, Rwanda. By recruiting former poachers, they helped us gather a lot of information on the poachers' networks; the types of snares; the other materials used and from where they got those materials; the target animals; the time of entering and getting out from the forest; the tracks used; the most frequented areas; and the time that they spend in the forest.

Karisoke and national authorities use the resulting information to reinforce the anti-poaching patrols and to efficiently sensitize local communities on biodiversity protection. Karisoke recruited one exceptional former poacher, who is now retired. We still have some former poachers working as trackers in with the gorillas' groups monitored by the Rwanda government for tourism. The recruited former poachers are welcomed by gorilla trackers! They are still considered as an asset to their daily work of gorillas' protection.

In addition, they have excellent experience in the forest! Some days, the tracking of gorillas is too hard or even unsuccessful, but the former poachers are consulted to find easy and right tracks! On other side, the resulting collaboration ended the friendships of the former poachers with their former colleagues, as they no longer share trust.

Today, the number of poachers has decreased. Most of them have been integrated in local organizations like traditional dancing troupes, handcrafts small-enterprises, and farming associations. But, some persisting poaching activities are observed; in 2010, Karisoke reported 1,927 snares.

AuthorBeth Green

Sosthene collecting data

This is the second in a series of posts about Sosthene Habumuremyi’s dissertation research on the hormonal correlations of socio-sexual behaviors in female mountain gorillas. Please see part one here.

By Sosthene Habumuremyi

My study has gathered data on mating behavior, solicitations, and any displays/aggression from adult males towards the females. Sexual swellings, which are extremely small in gorillas, are also noted.

The plan is to monitor at least 6 nulliparous (never having given birth to offspring) females and 10 cycling parous (given birth to offspring at least once) females for 2 cycles each (2-4 months per female) as well as obtain weekly measures from pregnant females. To ensure that the time of ovulation is measured hormonally, urine and or fecal samples must be collected regularly, on a nearly daily basis without gaps of more than 2-3 days.

My research on nulliparous mountain gorillas may answer these questions:

  1. Are cycles ovulatory?
  2. How do hormonal profiles relate to sexual swelling patterns and mating activities?
  3. How do hormonal profiles change with increasing age?
  4. How do hormonal patterns differ in comparison to parous females?

My research on cycling (parous) mountain gorillas may answer these questions:

  1. How does mating behavior relate to ovulation in parous females?
  2. How does mating behavior differ between one-male and multimale groups?
  3. How does mating behavior differ depending on whether the male is dominant or subordinate?
  4. How do patterns of mating solicitations (by the male or female) and potentially coercive behavior (aggression and displays by the males) vary according to reproductive status of the females?
  5. How do female hormone profiles vary in relation to the age of their dependent offspring, age of the female and proximity to conception?

Help Sosthene Habumuremyi become the first Rwandan to receive a PhD in Primatology

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189 gorilla pregnancy tests

By Sosthene Habumuremyi

The overall goal of this study is to investigate the hormonal correlates of socio-sexual behaviors in female mountain gorillas. Specifically, we want to understand the variation observed in mating strategies and fertility parameters among female mountain gorillas. By using hormonal data, we want to know if this variation is governed by internal stimuli. For a detailed analysis, we formulated multiple research questions, centered around different reproductive status of females. We selected our target individuals from nine gorillas groups monitored by Karisoke Research Center. In the field, we have been simultaneously collecting behavioral data as well as urine and feces samples.

Following the end of the field work, we’ll carry out the endocrinological measurements in the laboratory at the Max Planck. The results of this study will characterize the specific behavioral patterns around the time of ovulation in mountain gorillas, specifically mating behavior, patterns of mating solicitations, and any evidence of coercion (aggression) by the silverbacks directed towards the females. Furthermore, we will search for evidence of pregnancy losses. Also, we will provide additional information on adolescent sterility and sexual swellings in female mountain gorillas. The results of this study contribute to our understanding of fertility in gorillas, which is useful information for understanding the potential for the population to increase. Moreover, we hope that this research will help to provide useful information on the evolutionary profile of reproductive behaviors in primates.

Help Sosthene Habumuremyi become the first Rwandan to receive a PhD in Primatology

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Jeffrey Laitman (Mt. Sinai School of Medicine) will be speaking at The Field Museum in Chicago, on October 9th, as a part of The Leakey Foundation's Speaker Series on Human Origins. Below is an article, written by Dr. Laitman, describing the moment he realized his interest in studying primates.


The Magic of the Monkey House: New Insights Into the Anatomy that Makes Primates Primates Jeffrey T. Laitman Associate Editor,† | Article first published online: 16 MAR 2010 | DOI: 10.1002/ar.21131 | © 2010 Wiley-Liss, Inc.

De Brazza's Monkey at the Bronx Zoo Monkey House

The year 1958 began as a really horrible one for me. Two events made this so. The first occurred in the early spring when I realized that the Brooklyn Dodgers—our baseball team and the soul of Brooklyn—had abandoned us and fled to some bizarre place where people ate tacos instead of Nathan's franks and where it never snowed. Even their perennial nemesis—the New York Giants—left town for another unfathomable hamlet that was always having earthquakes. My almost 7-year-old mind could not fathom all this; the heroes I worshipped (Jackie Robinson often patted my little crew-cut head) were gone forever. I even became a Yankees fan.

My second crisis occurred before school ended in late spring. Our class had trip to the great American Museum of Natural History in Manhattan. I loved museum trips as I got to see dinosaurs, my second passion after the Dodgers. Tyrannosaurs, triceratops, hadrosaurs, I loved them all, but none more than the brontosaurus. I adored the big beasts with little heads, so much so, that I could not help but go under the ropes to climb on one's tail to get “up close and personal.” Caught in this act of defilement by a Goliath-sized museum guard, I was hauled off by the scruff of the neck (those were the days before “spare the rod” philosophy was in effect) and ejected from the Museum. My teacher banned me from future trips.

Ejected and branded (all but a scarlet letter emblazoned on my forehead) in my seventh year. To make matters worse, I had no project to write up for my school report; no postcards of dinos or stuffed grizzlies or meteorites to glue into a folder. I was sure the dreaded—and oft threatened—“summer school” would be my fate. And worst of all—what would I tell my mother? Oy!

As I sat on the front steps of our Brooklyn home, watching the other kids play stickball or marbles, I pondered the enormity of my failure. Lost in my melancholy, I didn't notice my father come home. I was glad he saw me before my mother as she was the disciplinarian and he a gentle Parisian who would say something I didn't understand in French and not get too angry. When I explained what happened, he just said he had an idea, and I should get up early on Sunday.

When Sunday arrived, my dad bundled me into our old Chevy and set off…to the Bronx Zoo. “Forget the dead animals,” dad said, “let's look at live ones.” This was my first time at the Bronx zoo and I was riveted to all the sights and sounds, but, truthfully, nothing set my heart to flutter. The elephants were big, but smelled foul; the seals and sea lions looked and sounded like dogs; the rhinos reminded me of garbage trucks; I was scared of cats the size of small cars. And then I saw a sight that would forever change my world: The Monkey House.

I sat and stared at the assortment of baboons and macaques and squirrel monkeys for most of the day. While I had seen some stuffed ones in the Museum, I never realized that these animals looked and acted so much like my family and friends. I even started to name them in my mind after relatives: there was Aunt Flo, big and bossy; Uncle Joe, snoozing away; Cousin Richie, climbing all over his brother Irwin, on and on. They had hands and fingers and toes that seemed to do all that I could do, and I envisioned them talking together and planning their day. And then it happened: as I pondered my new hairy family, a wad of poop landed smack on my crew-cut head, thrown by some impish baboon. “Wow!” my shocked little mind took a moment to cogitate, “Poop! They hit me with poop! These guys got attitude; they are definitely cool. They could make it in Brooklyn.”

A bond was forged that day between those poop-throwing cousins and me, one that has led me on my own career path: to understand our place among those remarkable relatives. Like most of us who spend our days trying to figure out why we pay taxes and these relatives don't, or how their historical trajectory landed them in the zoo and we were able to enjoy (albeit momentarily for some) the excitement of pondering dinosaurs at a museum, I'm always torn between my scientist's focused curiosity to discover the nuances of our collective anatomical similarities and a profound adoration for these kin. I know it might sound a tad odd to those whose science keeps them at some emotional distance from their object of study (I know you can't get too emotional over a zebrafish, drosophila, or an endoplasmic reticulum), but one of the traits I've found shared by primate biologists—anatomists, paleontologists, anthropologists, lab and fieldworker alike—is our emotional ties to the animals we study. There is undisputable joy in our science, but it is also inseparably coupled with an overriding knowledge that we are studying ourselves.

That fusion of scientific exuberance and “looking-in-the mirror” curiosity has been captured in this month's special issue of The Anatomical Record, “From head to tail: New models and approaches in primate functional anatomy and biomechanics,” guest edited by Jason Organ, Valerie DeLeon, Timothy Smith, and Qian Wang (Organ et al.,2010). This quartet of energetic primates collectively brings to our intellectual forest a robust array of knowledge and insights into cutting edge research on our closest relatives, empowering this issue to cover advances literally from top to bottom. Knowing these, now mature scientists from their intellectual pubescence as graduate students, I've watched their own fine work on tails and skulls, noses and teeth, help redefine our understanding of primate functional anatomy. These guest editors have traveled their own interesting, individual paths to find their love for our cousins: Jason planned on putting his Hebrew school training to good use as a biblical archeologist (his parents were probably so proud!); Valerie, ever the erudite scholar, enraptured by unraveling the intricacies of medieval European history, chartered a career as a field archeologist (and even managed to squeeze in a Law Degree and a stint as a tax attorney in the middle of all that; think of all the money she could have had!); Tim, a true heir of Da Vinci, had an art school background that sharpened his mind to see anatomy in extraordinary ways (not to mention producing outstanding artwork on primates in the process; see, e.g., Burrows and Smith (2003), and the beautiful covers of that issue and this special issue as well); and Qian, whose eight-year old mind was set afire with wonderful and wondrous visions through reading a lay book on primates by the great Chinese anatomist and paleontologist Ju-kang Woo (who, I was fortunate to know and communicate with often throughout my own career.) No matter what their original plans may have been, they all heard the “call of the wild,” so to speak, and were inextricably drawn to search for the Holy Grail of understanding primates.

For those among us that don't cohabitate a primatologists tree, a few words should be said about who primates are and why some of us go gaga over every third molar, tail bone, or nasal concha they possess. While some will argue incessantly that whales are brilliant, felines have consciousness, bees have grammar, or cockroaches will outlive us all (particularly the New York ones; I think I saw one last week with biceps), lets face facts, there's only one sheriff in town, and it's us. This was unambiguously recognized by Linnaeus (1758) who crowned us as “the first” or the “Primates” (spelled with a capital “P” and pronounced “pri-MAY-tees” only when used as the proper noun). To be fair, it is not always clear who has the primate credit-card and who doesn't, and this little point of contention has produced some pretty good arguments over the years (see classic reviews in Szalay and Delson,1979; Martin,1990; Fleagle,1999) Generally speaking, however, our Order consists of: the great (chimps, gorillas, orangs) and lesser (gibbons and siamangs) apes (rumor has it that gibbons at the Bronx zoo are protesting this condescending term; they have received support from “pygmy” chimpanzees and the “killer” whale lobby); monkeys (both Old World ones from Africa and Asia, and New World ones from the Americas); and a generally less well-known group, the prosimians, that include an assortment of lemurs from Madagascar, tarsiers, lorises, galagos, and the little tree shrews. This latter collection has sometimes been derogatively called “lower” primates due to their retention of somewhat more “primitive” features and the public's general lack of familiarity with them (although the “Madagascar” movies have made megastars out of species previously unrecognized outside of zoos.)

In addition to all the living primates listed above are all of our collective parents, grandparents, and relatives going back to the days when we all scrambled around as quasi-bipeds on the savannas of eastern and southern Africa. Indeed, for many of our ilk, the hunt to define a primate is inextricably tied to trying to figure out exactly who Homo sapiens is, and how our particular clan came to be. While arguments have existed aplenty as to who can claim inheritance to the primate lineage, they pale in comparison to the cataclysmic wars that have ensued regarding who is invited to sit at the “grownups” table of our own species. I have seen Distinguished Professors and members of national academies almost come to blow at anthropological or paleontological forums when the preeminence of their cherished fossils (or sacred ideas) have been challenged [to get an idea of the extent of the anger and combativeness that can surround studies on human origins, see the chapter on “Johanson versus the Leakeys” in Hellman (2007)]. To put things in perspective, disagreeing about the importance of someone's fossil is the equivalent to calling their baby “ugly”; go there at your own peril. In the paleoanthropological world, no one gets stars for having the second most important fossil; “close” only counts in horseshoe throwing, not in hominid phylogenetics. At its core, every study of primates, somewhere, somehow, addresses an issue of our own species trajectory.

Pooling their collective energies and interests, our editorial quartet have put together an excellent array of hypothesis-driven science that presents the latest in techniques and approaches searching for those elusive elements that make primates, well, primates. In true comparative mode, the work herein spans the spectrum from modeling studies using nonprimate mammals to examination of humans, with members of our brethren from little bushbabies, to South American monkeys, to baboons, to apes, all making appearances. And the nooks and crannies that are investigated would warm any comparative primate anatomist's heart. Studies take us from prosimian shoulder morphology to the inside of galago noses, from how South American monkeys got their tails to how our weight bearing long bones came to carry their weight. For those among us who are cranial cognoscenti, there are many studies to warm our bones, assessing various aspects of teeth, mandibles, and assorted crevices of the face and vault.

As noted above, the quest for insight into the nature of human origins and human anatomy weaves its way through many studies. Some directly tackle the issue by investigating adaptations and biomechanics among groups of ancestral hominids such as Plio-Pleistocene Australopithecus or enigmatic near-relatives such as the ever-pesky Neanderthals. Many other studies integrate their findings on specific topics with aspects that humans share with other species, or how humans may display autapomorphic features (uniquely derived traits) in these regards. Observations are often tantalizing, and readers will have much to chew on.

Of particular interest to those of us primates whose age is starting to show in our temporal regions, is the potency and diversity of the methods employed in these studies. Our field—and here I refer to primate comparative anatomy and its subsets in aspects of physical anthropology—has come a long, long way from simple calipers measuring a few craniometric points. Don't get me wrong, lumps and bumps have been my bread and butter, and I love my calipers dearly (I also loved my slide-rule—any of you remember these?), yet, we have come a long way from relying solely upon gross dissection or linear measurements. The potency of new technologies, sometimes alone sometimes melded with the strength of the old, can be seen throughout this issue. Indeed, the power of experimental approaches to anatomy, new microanatomical techniques, kinematic and kinetic biomechanical approaches, high-resolution computed tomography (CT), or assessment via Finite Element Modeling and analysis are some of the arrows in the quivers of the cutting-edge papers offered in this special issue. The power of the future is clearly put forward.

“Get off the fence kid,” bellowed the Bronx Zoo guard, “no leaning on the rail.” “I wasn't hurting anything, Mister, just trying to get a closer look at the monkeys,” I tried to explain. “Didn't ya hear me, kid!?” Goliath roared, “I said get your butt…” At this exact moment—forever given a hallowed place in my mind's eye—a wad of poop landed smack in the middle of his bulbous Bronx nose. The zoo guard ignominiously retreated, spewing forth a cacophony of words I was told never to use. It was the perfect ending to the perfect day.

Oh, by the way, I never told my mother what happened at the museum. There was no need to, as I got the highest grade in the class for my report: The Magic of The Monkey House.

Literature Cited

Burrows AM,Smith TD. 2003. Muscles of facial expression in Otolemur, with a comparison to Lemuroidea. Anat Rec 274A:827–836. Direct Link:  Abstract |  Full Article (HTML) |  PDF(578K) |  References

Fleagle JG. 1999. Primate adaptation and evolution. 2nd ed. San Diego, CA: Academic Press.

Hellman H. 2007. Great feuds in science: ten disputes that shaped the world. New York: Barnes & Noble.

Linnaeus C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines genera, species cum characteribus, differentris, synonymis, locis. Editis decimia, reformata. Stockholm: Laurentii Salvii.

Martin RD. 1990. Primate origins and evolution. A phylogenetic reconstruction. Princeton: Princeton University Press.

Organ JM,DeLeon VB,Wang Q,Smith TD. 2010. From head to tail: new models and approaches in primate functional anatomy and biomechanics. Anat Rec 293: 544–548. Direct Link: Abstract |  Full Article (HTML) |  PDF(63K) |  References


This article first appeared in The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology Special Issue: From Head to Tail: New Models and Approaches in Primate Functional Anatomy and Biomechanics Volume 293, Issue 4, pages 541–543, April 2010 The Magic of the Monkey House: New Insights Into the Anatomy that Makes Primates Primates Jeffrey T. Laitman Associate Editor, Article first published online: 16 MAR 2010 DOI: 10.1002/ar.21131 Copyright © 2010 Wiley-Liss, Inc.

AuthorBeth Green

In partnership with The Department of Expansion, The Leakey Foundaiton has launched a series of four short films.

Today, on, Leakey Foundation friend Frans de Waal wrote an article for the Guest Blog, with accompanying short film "The Bi-Polar Ape." This film is part of a four part series on human behavior and evolution.

AuthorBeth Green