Alexandra Rosati, Ph.D. - US grants

DESCRIPTION (provided by applicant): While it is clear that lifespan was extended during human evolution, there is remarkably little data available to assess the specific ways by which this remarkable change in life history came about. This missing information could importantly inform the understanding of how modern lifestyles, in interaction with our evolved biology, produce the health outcomes observed in developed countries. A major limitation at present is a dearth of data on the aging process in humans' closest evolutionary relative, the chimpanzee. The current study would be the first to gather comprehensive data on aging in wild chimpanzees, whose health has not been manipulated by humans during captive management or biomedical experimentation. Like humans during most of their evolutionary history, wild chimpanzees experience frequent nutritional stress and high rates of infectious disease and these processes - little studied in modern aging research - are expected to have shaped species-normative life history strategies. The project entails non-invasive collection of urine and feces from approximately 245 wild chimpanzees (Pan troglodytes) for a broad range of health biomarkers, in additional to observational research for observed morbidity, locomotor proficiency, and social behavior. New data collection will complement and extend existing long-term demographic data, as well as individual histories of social interaction and reproductive effort. The wild data will be supplemented by additional blood-based biomarkers obtained during routine veterinary immobilizations of approximately 240 semi-free ranging chimpanzees in African sanctuaries. The project integrates investigators from major studies of health and aging in human foraging populations, and the central aim (1) of the project is to perform structured comparisons of health and aging between humans and chimpanzees. To further this goal, the additional project aims focus on key variables that are expected to shape senescence, and which are associated with prominent behavioral differences between species: (2) sex differences and the allocation of reproductive effort across the life history, (3) stability of accss to energy, and (4) social status and support. Information gathered in pursuit of these aims has specific relevance to prominent focuses of human aging research: the gender morbidity-mortality paradox, caloric restriction, and the influences of chronic stress and social subordination.

Leadership is crucial for effective cooperation, especially in large and complex groups. Yet there is an empirical and theoretical gap in our understanding of the individual-level processes underpinning leadership and the group-level consequences of leadership. How does the cognition of individual leaders translate into coordinated group action in the real world? This project proposes using chimpanzees as a new model of human-like leadership to better understand the evolutionary origins of our own leadership patterns. We will bridge the gap between individual- and group-level phenomena by conducting matched research with semi-free ranging chimpanzees living in a sanctuary where we can do detailed assessments of cognition, and with chimpanzees living in the wild where we can look at complex group behavior in a natural setting. By matching datasets across these two contexts, we will be able to see how individual cognitive process translate into group action. While humans are thought to be uniquely able to establish leadership through prestige and collaboration instead of just pure physical domination, chimpanzees are our closest living relative, also show variation in how individuals obtain and maintain status in their groups. This project will therefore illuminate the evolutionary origins of human leadership, and also set a new agenda in evolutionary cognitive science for studying cognition in the wild. Training, education, and outreach from elementary school through to graduate school will be integrated throughout the project both domestically and abroad. As part of this proposal, we will develop a leadership module for children, using animal models to demonstrate different forms of leadership. We will implement this module through outreach at local schools and museums in the US and in 16 primary schools in Uganda. Undergraduates and high school students in the US will gain hand-on research experience through internships and in coursework. Two postdoctoral researchers and a graduate student will further gain international research experiences in the course of the project. This integrated approach to research and education will train a new generation of evolutionary cognitive scientists and disseminate primate research to the public.

This project has three specific aims. The first aim is to identify individual leaders (those with outsized influence) in natural social groups across multiple contexts of behavior including dominance rank, initiation of group movements, resource acquisition, within-group mediation and inter-group aggression. The second aim is to create leadership profiles by characterizing individual variation in the cognitive, behavioral, and physiological mechanisms of leaders across these contexts. At the sanctuary, 100+ chimpanzees across 5 social groups will be assayed for cognition (including social cognition, cooperation, and executive function); temperament; behavior (aggression and affiliation), and physiology (hormones and body size) to predict leadership. At the field site, similar assessments will be made of temperament, behavior, and physiology, drawing on a longitudinal database with 30 years of data on 150 wild chimpanzees. These data will be used to test the hypothesis that there are distinct pathways to leadership in chimpanzees, with intimidation-based and cooperative strategies being the most important, but knowledge and motivation anchoring some forms of leadership. The final aim is to understand how variation in leadership styles shapes the outcomes of collective action by examining several short-and long-term metrics of leadership success, including group cohesion, rewards received, and biological outcomes like reproductive success that can only be studied in the wild. This project will bridge individual-level and group-level perspectives on cognition, behavior, and physiology by leveraging the strengths of two natural populations of chimpanzees. The project will match experimental and observational techniques across sites on a scale never previously done, and will develop chimpanzees as a new model for human leadership.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

The social environment is thought to play a major role in the fate of social mammals, including humans. For example, socially advantaged individuals often have more access to resources resulting in better health, more offspring, and longer lives, relative to socially disadvantaged individuals who often experience harsher environments. However, it is still unclear how social aspects in the life of mammals affect the ecological and evolutionary dynamics of their populations. This knowledge gap deepens for mammals with complex social behaviors, long lifespan, and flexible cognitive abilities such as primates. This project seeks to understand whether the effects of sociality on individual fates ultimately translates into population-level processes using data of rhesus macaques, a nonhuman primate. This goal will be accomplished by establishing a research team built on a foundation of education and training aimed at broadening opportunities for quantitative and field research for students at a Primarily Undergraduate and a Minority-Serving Institution where over half of the total student body also comes from first-generation college, low-income backgrounds. In this way, this project will contribute to the national initiative of increasing diversity of the STEM research workforce by integrating training and mentorship to broaden access to interdisciplinary biology and quantitative skills to mentees from diverse backgrounds.<br/><br/>This project will identify how and why socially driven individual differences have direct and significant effects on the eco-evolutionary dynamics of a primate population, linking current research in the social determinants of individual variability to evolutionary demography approaches to the fundamental rules of life history evolution. The project will take an interdisciplinary approach by jointly examining empirically collected behavioral, physical, and cognitive factors within a single system, and then using this data to test the eco-evolutionary consequences of the social environment in a large population of rhesus macaques (Macaca mulatta) at Cayo Santiago, Puerto Rico. The first aim is to characterize the distribution of socially driven individual phenotypes, comprising both physical and cognitive traits, across the lifespan. This will be used to test whether physical and cognitive phenotypes vary across individuals in relation to their social status. The second aim is to quantify phenotype-dependent demographic performance across the population’s social structure. Here, a demographic model will be formulated using the observed associations between individual phenotypes and sociality from Aim 1. The third aim is to test whether sociality generates selection gradients on demographic and life history descriptors by examining how the strength and direction of selection varies across social stratification. For this, the parameterized demographic model from Aim 2 will be used to carry out joint perturbation analyses on phenotype-demography functions. This framework will be used to evaluate whether sociality supports the emergence and maintenance of individual phenotypes driving eco-evolutionary processes within populations.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.