Young blue monkey

Though the wild blue monkey (Cercopithecus mitis) has a social structure of one-male social groups, this organization can be somewhat dynamic.  Hence, resident males do not always have a reproductive monopoly over the females, and non-resident (bachelor) males may have a higher reproductive success than one might expect.

Su-Jen Roberts


Su-Jen Roberts, PhD candidate from Columbia University, was awarded a research grant in spring of 2012 for her project to asses what variables drive variance in reproductive success in wild blue monkeys. The report below describes how Roberts used DNA analysis to assign paternity to the study population in the Kakamega Forest, Kenya.  She then combined these results with long-term observational data in order to better understand how variables such as female reproductive synchrony or the number and proximity of competitor males affect the reproductive success of resident and bachelor males.   

Posted
AuthorH Gregory

Julia Ostner
University of Göttingen

Female Assamese macaque

Researchers have been performing daily focal observations and fecal sampling on this study group of habituated Assamese macaques in Thailand’s Phu Khieo Wildlife Sanctuary since October 2006.  For her investigation of ecological, social and reproductive stress in female macaques, Julia Ostner used data collected between September 2007 and February 2009. This time period included two events that resulted in periods of marked social instability for the group, the death of an adult female and later that year the death of an alpha-male at the hands of co-resident males.

In the report below Ostner summarizes her team’s progress in disentangling the sources of physiological stress and their effects on female primates. 

Posted
AuthorH Gregory

Paco BertolaniPhD Candidate
University of Cambridge

The Tshuapa-Lomami-Lualaba area (TL2) lies at the eastern edge of the bonobos’ species range in the Congo basin. In what eventually led to the creation of the TL2 Project, Terese and John Hart organized extensive surveys of TL2 starting in 2007. They confirmed the presence of bonobos in this area, estimating a population of over 10,000 individuals. This relatively pristine, remote habitat had the potential to be an area of extraordinary importance for the future of bonobos.

In a Leakey Foundation research grant awarded in spring of 2011, Paco Bertolani proposed a pilot study to assess the feasibility of establishing a long-term site for bonobo behavioral research (and conservation) in TL2. He and his team would conduct surveys in search of bonobo traces. This would include detailed mapping of the study area as well as the collection of fecal samples for genetic analysis and surveying the health of the bonobos. They would also monitor signs of hunting and other human disturbance in collaboration with TL2 Project staff.

In the report below, Bertolani summarizes the results of his team’s findings, including his assessment of the feasibility- and riskiness- of establishing a long-term bonobo research site in TL2 where poaching is a serious problem.

Posted
AuthorH Gregory

Anne E. Russon
York Univesity

Anne E. Russon

In spring 2012 The Leakey Foundation awarded Anne E. Russon a grant for her long-term study of behavior in east Bornean orangutans (Pongo pygmaeus morio) at the Bendili study area located in Kutai National Park.  This project focused specifically on orangutan ranging, feeding ecology and spatial cognition. 

Researchers have studied orangutans in the Bendili and nearby Mentoko study areas several times over the last 44 years.  During this time their habitat has undergone drastic changes, including commercial logging incursions, severe droughts and massive forest fires. In the report below Russon describes some of her team’s findings, including how intra-site comparisons of activity budgets and travel distances provide insight into how these orangutans coped with this series of habitat changes. 

Posted
AuthorH Gregory

Brigitte Spillmann, PhD Candidate
University of Zurich, Switzerland

Approved:  April 2010


Original Abstract

Long-distance communication in a widely dispersed, semi-solitary species mediates individuals ranging behavior and social relationships. Long calls are the most conspicuous vocalization in orangutans. They are emitted only by flanged males and serve as a long-distance signal and are therefore key regulators of encounters between dispersed individuals in a dense rainforest where visibility is limited. Two functions of flanged male long calls are generally considered: repulsion of male rivals and mate attraction. Nevertheless, long call function is poorly understood, given that recent work in our group has shown that: (i) there is a third likely function, travel coordination with non-receptive females; (ii) long calls can be divided into acoustically distinct types; and (iii) social systems, and in particular male-male competition and male-female relationships, differ between Sumatran and Bornean orangutans. In this project, we intend to examine all three possible functions of long calls and their information content on both islands, in order to elucidate the flexibility of vocal signaling in geographically variable social system.

To understand human evolution, be it our morphology or our mind, study of great apes is essential because a composite picture of the great apes' social systems and communication 

The combination of traditional follows and novel auditory monitoring will create an accurate picture of flanged males' presence in the area should be more accurate, and thus allow us to reconstruct a model of the communication network over time and space. In addition, playback experiments will answer questions about females' and males' reactions to long calls in a controlled way and thus to elucidating long call function. 

Posted
AuthorH Gregory

Varsha C. Pilbrow, PhD
University of Melbourne

Co-Investigator:  Shara Bailey, New York University

Approved:  December 2011


Original Abstract

Descriptions of non-metric or discrete dental traits form a large part of the taxonomic and phylogenetic diagnosis of fossil hominids. New diagnoses often engender debate with regards to how the ranges and patterns of dental variation in the fossils compare with variation in living great apes and humans. Since objective comparisons with living taxa are rarely included in the initial descriptions such debates seem to be without resolution. The purpose of this project is two-fold: (1) to examine the nature of variation in non-metric dental traits in Pan, Gorilla and Pongo, and (2) to use great ape traits and trait expressions to re-assess the taxonomy of southern African hominins. We will test the hypotheses that (1) the great ape and human phylogeny can be accurately reconstructed from dental traits, and (2) dental traits have taxonomic and phylogenetic relevance. We will construct plaster plaques documenting variants in the expression of discrete dental traits and use phylogenetic methods to reconstruct the great ape and human phylogeny already established from molecular data. This study will (1) establish the importance of dental traits for fossil taxonomy and phylogeny, and (2) provide a comparative hominid database of standardized traits and trait variants with which to compare fossil taxa. Given the predominance of teeth in fossil assemblages we expect this study to have wide application in fossil hominid systematics. As a test case, we will use great ape dental traits and trait expressions to re-assess the taxonomy of Paranthropus and Australopithecus in southern Africa. These taxa exemplify the debate on the taxonomic and phylogenetic relevance of dental traits for fossil hominid systematics, thus will provide good resolution of the debate. 

Posted
AuthorH Gregory

Barbara Tiddi, PhD
German Primate Center

Approved:  December 2011


Original Abstract

The present project focuses on aspects of female mating strategies in a species which has been described as exhibiting "female choice". In particular, this research investigates whether female tufted capuchin monkeys (Cebus apella nigritus) adopt specific mating strategies to solve potential conflicts with both males and other females. In examining conflicts with males, the study asks: do capuchin females convey behavioral and acoustic sexual signals via graded-systems?; do females adopt strategies to confuse paternity? Considering conflicts with other females, the study focuses on the following questions: do females compete directly and indirectly  to mate with the alpha male? Do females compete indirectly by engaging in non-conceptive mating?. Tufted capuchin females show at least two features that make them an ideal system from which to examine human sexual behavior from a comparative perspective. First, capuchin females, like human females, solicit their mates mainly through behavioral and vocal cues. Second, capuchin females are extremely active in soliciting males, contrasting with traditional portrayals of females as passive partners. Likewise, the production of effective mate-attracting behaviors has been proposed to be a prevalent component female mating strategies of intrasexual mate competition in humans. Therefore, studies examining mating strategies in a primate species with similar patterns of sexual behaviours and sexual signaling will provide a better model for understanding sexual signaling and mating strategies among humans. The study will be conducted on three wild groups of tufted capuchin monkeys over two mating seasons in Iguaz˙ National Park, Argentina. Factors influencing female mating strategies will be examined by integrating behavioral observations on mating patterns and sexual behaviors with analyses of reproductive hormonal profiles and bio-acoustic analysis of proceptivity calls.

Posted
AuthorH Gregory

Michelle Kline, PhD Candidate
University of California, Los Angeles 

Approved:  May 2011


Original Abstract

The objective of this research is to test predictions of the hypothesis that cumulative cultural evolution is integral to human adaptation, and that humans possess unique social learning capacities that have coevolved with culture. This research is theoretically important to cultural evolutionary theory because these data will constitute the most extensive existing data set on cultural transmission outside the laboratory. This pursuit matters for the study of human origins, because culture is a major source of human adaptability, and because interpreting the early hominin archaeological record accurately requires empirically verified theory about how cultural transmission creates patterns of cultural variation.

This project has four aims: (1) test whether subtle teaching is important to social learning in a small-scale society; (2) measure within-group variation in knowledge relevant to adaptive skills; (3) test whether theorized learning biases generate adaptive behavior outside the laboratory; and (4) measure patterns of social interaction to infer the geometry of cultural information networks.

The work will take place in villages on Yasawa Island, Fiji. Each village is about 100 people, who subsist mainly on fishing and horticulture. Political units are composed of interrelated clans, a council of elders, and a hereditary chief. There are no local markets, broadcast television, automobiles, or public utilities here. Since face-to-face societies like this one are where most of the world's population lives, and are more similar to the environments to which the human mind has evolved, this is an ideal setting for this study. The researcher will collect data using mixed methodology, including focal follows, structured interviews, and video-recorded observation and video-assisted interviews. She will also conduct collect physiological health measures.

 




Posted
AuthorH Gregory