Amboseli baboon

Exaggerated sexual swellings and male mate choice in primates

Author: Courtney Fitzpatrick



The exaggerated estrous swelling displayed by females of many Old World primates has often been thought of as a trait that functions as a reliable indicator of individual female quality. Indeed, baboon swellings are regularly held up as the text-book example. This idea is based on Pagel (1994), which put forward the Reliable Indicator Hypothesis. This hypothesis posited that the exaggerated swellings of some females are consistently larger than others (i.e. inter-individual variation in size), that this swelling size is an indicator of heritable female ‘quality’ (quality that translates into variation in lifetime reproductive success), and that males therefore prefer those females that have larger swellings. Previous work in the Amboseli baboons provided support for the first part of the reliable indicator hypothesis; swellings of some females are indeed larger than others (Fitzpatrick et al. 2014). However, until the recent study by Amboseli researchers, a complete test of the Reliable Indicator Hypothesis had not been conducted in any primate population. Read More

Measuring testosterone in female and estrogens in male baboons

Author: Laurence Gesquiere


Traditionally, testosterone is thought as a male hormone and estrogens as female hormones. However, estrogens and testosterone are produced by both sexes and appear to have important roles in both males and females.  Measuring hormone concentrations in the wild without disturbing the animals is now feasible using non-invasive methods like fecal determination. These methods, however, need careful validation as the circulating hormone is usually degraded into several metabolites and it is necessary to verify that the antibody used in the immunoassay only recognized metabolites of the original hormone.  Because the metabolites excreted in feces may be different for males and females, it is essential to validate immunoassays in both sexes. In this study, we determined whether the radioimmunoassays we previously used to measure fecal testosterone in male baboons and fecal estrogens in female baboons were suitable to measure these hormones in the opposite sex. Read More

Family influences dominance rank in female baboons

Author: Amanda Lea



There's a new ABRP paper out on predictors of female dominance rank. Dominance rank influences many fitness-related traits in the Amboseli baboons and in other mammalian populations. Therefore, understanding how and why animals attain a given dominance rank is an important goal in behavioral ecology. For female baboons, dominance rank is maternally inherited and generally follows predictable patterns. Specifically, adult daughters attain a rank immediately below their mother, and in reverse age order (a phenomenon known as ‘youngest ascendency’). This pattern of rank inheritance is assumed to be widespread and generally stable in cercopithecine primates; however, few studies have systematically examined whether the rules of female rank inheritance always hold true, and under what circumstances they are violated. Read More

Collaborating institutions

Princeton, Duke, and Notre Dame

Princeton University

Duke University

University of Notre Dame


Amboseli baboon research project

Located near Amboseli National Park in Kenya, ABRP is one of the longest-running studies of wild primates in the world. ABRP is directed by Dr. Jeanne Altmann at Princeton University, and Dr. Susan Alberts at Duke University. The Associate Directors are Dr. Beth Archie at the University of Notre Dame and Dr. Jenny Tung at Duke University. Click the links at left to learn more about the project and our research.The Amboseli baboons.

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