Professor Elizabeth Lonsdorf

I am an Associate Professor of Psychology and a member of the Biological Foundations of Behavior Program at Franklin and Marshall College in Lancaster, PA, USA.  I study primate behavior, learning, development and health. My current research focuses on behavioral development and the intersection of health and behavior in wild chimpanzees, and social learning and tool use in a variety of primate species.  I conduct my research on chimpanzees at the Gombe Stream Research Centre in Tanzania, and on the two capuchin monkey families that call F&M home.  See below for recent research findings.

Latest research


Age at weaning is a key life history characteristic. However, almost nothing is known about sources of variation in chimpanzee weaning ages. Here we use the long-term data from Gombe Stream Research Centre to examine these sources. Sons and offspring of low-ranking mothers took longer to wean relative to daughters and offspring of higher-ranking mothers. Individual variation between mothers was substantial. The link to the publication can be found here. This work was supported by the National Science Foundation.  Photo courtesy J. Bray.

A multi-year collaboration between researchers at Gombe Stream Research Centre and Goualougo Triangle Ape Project shows that teaching varies with task complexity in wild chimpanzees. At Goualougo, where termite-fishing is more complex, mothers are more likely to share their tools with offspring than at Gombe, where termite-fishing is simpler. Understanding how chimpanzee tool traditions are passed on over generations can provide insights into the evolutionary origins of complex cultural abilities in humans. The publication can be found here, with commentary by Andrew Whiten here. Photo courtesy K. Walker.

We know very little about nonhuman primate attentional preferences for same- versus opposite-sex faces. This paper is one of the first to use a noninvasive eye-tracking paradigm to examine face preferences in capuchin monkeys.  Here is the link to the publication.  Read more about our work in the monkey lab here and here.

Apart from the crucial bonds between mothers and offspring, siblings are an important first social partner in most primate species.  Here, we used 24 years of long-term data from wild chimpanzees in Gombe National Park, Tanzania, to characterize
maternal sibling-infant relationships and investigate sex differences therein.  We found that interactions differed according to the sex combination of sibling-infant dyad, which may have consequences for the social development of both individuals.  The link to the publication is here.

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