• Primate Behavior Lab

    Department of Anthropology | University of Michigan

    The members of our lab study the evolutionary causes and consequences of the behavior and physiology of primates, including humans. Much of our research focuses on the wild mountain gorilla population monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center in Rwanda.

  • Research


    Primate behavior is unusual in many ways. We study how primates interact with one another and with their environment. The goal is to understand how behavior influences their health, reproduction, and longevity, and use this information to make inferences about the evolutionary history of the primate order.


    Physiological processes such as reproduction, growth, and metabolism provide important information about why primates behave the way they do. We use non-invasive methods to study what happens inside of primates' bodies, and how it relates to their social and environmental landscapes.

  • Publications

    Papers written by our lab members

    Hormones & behavior

    Gettler LT, Rosenbaum S, Kuo PX, Sarma MS, Bechayda SA, McDade TW, & Kuzawa CW. (2022). Evidence for an adolescent sensitive period to family experiences influencing adult male testosterone production. PNAS, 119 (23) e2202874119.


    Grebe NM, Sheikh A, & Drea CM (2022). Integrating the female masculinization and challenge hypotheses: female dominance, male deference, and seasonal hormone fluctuations in adult blue-eyed black lemurs. Hormones & Behavior, 139, 105108.


    Rosenbaum S, Eckardt W, Stoinski TS, Umuhoza R, Kuzawa CW, & Santymire RM (2021). Group structure, but not dominance rank, predicts fecal androgen metabolite concentrations of wild male mountain gorillas. American Journal of Primatology, e23295.


    Rosenbaum S, Stoinski TS, & Santymire R (2020). Urinary androgens, dominance hierarchies, and social group structure among wild male mountain gorillas. In Chimpanzees in context: a comparative perspective on behavior, cognition, conservation, and welfare (Hopper L & Ross S, eds.). University of Chicago Press, Chicago IL, 137-166.


    Eckardt W, Stoinski TS, Rosenbaum S, & Santymire RS (2019). Social and ecological factors alter stress physiology of Virunga mountain gorillas (Gorilla beringei). Ecology and Evolution, 9, 5248-5259.


    Rosenbaum S, Gettler LT, McDade T, Augustin S, & Kuzawa CW (2018). Does men’s testosterone ‘rebound’ when dependent children grow up, or when pair bonds end? A test in Cebu, Philippines. American Journal of Human Biology, e23180.


    Gettler LT, Kuo P, Rosenbaum S, Avila J, McDade T, & Kuzawa CW (2018). Sociosexuality, testosterone, and life history status: prospective associations and longitudinal changes among men in Cebu, Philippines. Evolution and Human Behavior, DOI: 10.1016/j.evolhumbehav.2018.11.001.



    Paternal care

    Rosenbaum S* & Silk JB* (2022). Pathways to paternal care in primates. Evolutionary Anthropology, https://doi.org/10.1002/evan.21942.


    Rosenbaum S, Kuzawa CW, McDade TW, Avila J, Bechayda SA, & Gettler LT (2021). Fathers' care in context: 'facultative,' flexible fathers respond to work demands and child age, but not to alloparental help, in Cebu, Philippines. Evolution and Human Behavior, 42(6), 534-546.


    Gettler LT, Boyette A, & Rosenbaum S (2020). Broadening perspectives on the evolution of human paternal care and fathers' effects on children. Annual Review of Anthropology, 49, 141-60.


    Rosenbaum S, Vigilant L, Kuzawa CW, & Stoinski TS (2018). Caring for infants is associated with increased reproductive success for male mountain gorillas. Scientific Reports, 8:15223.


    Rosenbaum S, Hirwa JP, Silk JB, Vigilant L, & Stoinski TS (2016). Infant mortality risk and paternity certainty are associated with postnatal maternal behavior toward adult male mountain gorillas. PLoS One, DOI: 10.1371/journal.pone.0147441.


    Rosenbaum S, Hirwa JP, Silk JB, & Stoinski TS (2016). Relationships between adult male and maturing mountain gorillas persist across developmental stages and social upheaval. Ethology, 122, 134-150.


    Rosenbaum S, Maldonado-Chapparo AA, & Stoinski TS (2015). Group structure predicts variation in proximity relationships between male-female and male-infant pairs of mountain gorillas. Primates, 57, 17-28.


    Rosenbaum S, Hirwa JP, Silk JB, Vigilant L, & Stoinski TS (2015). Male rank, not paternity, predicts male-immature relationships in mountain gorillas. Animal Behaviour, 104, 13-24.


    Rosenbaum S, Silk JB, & Stoinski TS (2011). Male-immature relationships in multi-male groups of mountain gorillas. American Journal of Primatology, 71, 1-10.



    Alloparental care

    Rosenbaum S, Kuzawa CW, McDade TW, Bechayda SA, & Gettler LT (2022). Neither environmental unpredictability nor harshness predict reliance on alloparental care among families in Cebu, Philippines. Development and Psychopathology, 1-12, DOI: 10.1017/S0954579421001711.


    Rosenbaum S & Gettler LT (2018). With a little help from her friends (and family) I: the ecology and evolution of non-maternal caretaking in mammals. Physiology & Behavior, 193, 1-11.


    Rosenbaum S & Gettler LT (2018). With a little help from her friends (and family) II: the behavior and physiology of non-maternal caretaking in mammals. Physiology & Behavior, 193, 2-24.



    Early life adversity

    Rosenbaum S, Zeng S, Campos FA, Gesquiere LR, Altmann J, Alberts SC, Li F, & Archie EA (2020). Social bonds do not mediate the relationship between early adversity and adult glucocorticoids in wild baboons. PNAS, 117(33), 20052-20062.


    Lea A* & Rosenbaum S* (2020). Understanding how early life effects evolve: Progress, gaps, and future directions. Current Opinion in Behavioral Sciences, 36, 29-35.




    Malani A*, Rosenbaum S*, Alberts SC, & Archie EA (2022--PREPRINT). Seeing the future: a better way to model and test for adaptive developmental plasticity. bioRxiv, DOI: 10.1101/2022.02.10.479998v1


    Zeng S, Rosenbaum S, Archie EA, Alberts SC, & Li F (2021). Causal mediation analysis for sparse and irregular longitudinal data. Annals of Applied Statistics, DOI: 10.1214/20-AOAS1427.


    Rosenbaum S, Gettler LT, McDade TW, Belarmino NM, & Kuzawa CW (2018). The effects of collection and storage conditions in the field on salivary testosterone, cortisol, and sIgA. Annals of Human Biology, DOI: 10.1080/03014460.2018.1495263.


    Eckardt W, Stoinski TS, Rosenbaum S, Umuhoza MR, & Santymire R (2016). Validating faecal glucocorticoid analysis in the Virunga mountain gorilla using a natural biological stressor. Conservation Physiology, 4, cow029.




    Rivera CJ, Mayo D, & Hull V (2021). Social-ecological interactions influencing primate harvest: insights from Madagascar. Frontiers in Conservation Science, DOI: 10.3389/fcosc.2021.776897.


    Knott CD, Kane EE...Brown ER... & Susanto TW (2021). The Gunung Palung Orangutan Project: Twenty-five years at the intersection of research and conservation in a critical landscape in Indonesia. Biological Conservation, 255, 108856.




    Grebe NM, Hirwa JP, Stoinski TS, Vigilant L, & Rosenbaum S (2022). Mountain gorillas maintain strong affilative biases for maternal sibilings despite high male reproductive skew and extensive exposure to paternal kin. eLife, 11, e80820. 


    Kuzawa CW, Adair L, Bechayda SA, Borja JRB, Carba DB, Duazo PL, Eisenberg DTA, Georgiev AV, Gettler LT, Lee NR, Quinn EA, Rosenbaum S, Rutherford J, Ryan C, & McDade TW (2020). Evolutionary life history theory as an organizing framework for cohort studies: Insights from the Cebu Longitudinal Health and Nutrition Survey. Annals of Human Biology, 47(2), 94-105.


    Rosenbaum S (2018). Offspring defense. In Encyclopedia of Evolutionary Psychological Science (Shackelford TK & Weekes-Shackelford VA, eds.). Springer. DOI: 10.1007/978-3-319-16999-6_1904-1.


    Rosenbaum S, Vecellio V, & Stoinski TS (2016). Observations of severe and lethal coalitionary attacks in wild mountain gorillas. Scientific Reports, 6, 37018.


    Stoinski TS, Rosenbaum S, Ngaboyamahina T, Vecellio V, Ndagijimana F, & Fawcett K (2009). Patterns of male reproductive behavior in multimale groups of mountain gorillas: examining theories of reproductive skew. Behaviour, 146, 1193-1215.


    Stoinski TS, Vecellio V, Ngaboyamahina T, Ndagijimana F, Rosenbaum S, & Fawcett K (2009). Proximate factors influencing dispersal decisions in male mountain gorillas. Animal Behaviour 77, 1155-1164.


    *Authors contributed equally

  • Current projects

    Brief overviews of some things we're working on

    Social behavior, adaptive responses, and developmental constraints

    There is a large body of research on the connections between early life conditions (e.g. environmental factors like resource abundance, but also social factors such as caregiving environments) and later-life outcomes . Are the downstream outcomes adaptive responses that maximize lifetime fitness (e.g. the predictive adaptive response hypothesis), or are they simply the result of constraints imposed by environmental realities during development (e.g. the developmental constraints hypothesis)?


    Prior research in this area has focused heavily on epigenetic and physiological mechanisms, and has not yet leveraged the fundamental role that behavior generally, and social behavior specifically, may play. This project is a collaboration with Dr. Beth Archie, and uses data from the Amboseli Baboon Research Project. The baboons’ high environmental variability, male dispersal, and strong female dominance hierarchies make them an ideal system to study how social variables interact with ecological ones, and how the relationship between early life experiences and later outcomes is mediated by social bonds and intraspecific competition.

    Reproductive strategies and steroid hormones in non-seasonal breeders

    There is an extensive body of literature on the endocrine system switches that occur as seasonally-breeding organisms shift from mating to parenting effort and back again (aka the Challenge Hypothesis). The Challenge Hypothesis is a powerful framework for understanding hormonal mechanisms and reproductive effort in some species, but its predictive power is limited in non-seasonal breeders, and it treats “mating effort” and “parenting effort” as monoliths rather than the complex suite of behaviors each actually represents. In species such as mountain gorillas and humans, non-seasonal breeding is combined with extended offspring development, during which males offer both direct and indirect care. Organisms like these offer ideal opportunities to understand how hormonal mediators work when competing needs must be balanced.


    Using longitudinal behavioral and hormonal data from both gorillas and humans, we are exploring how steroid hormones are related to intra- and inter-individual variation in male reproductive strategies, including caretaking. Across the two species, this research addresses hypotheses about (for example) the effect alloparental care has on males’ testosterone profiles, and how testosterone profiles respond to the changes in caretaking behavior that occur as offspring age and become less reliant upon intensive care.

    Male development and life history strategies

    Male mountain gorillas go through a period of uncertainty after they've become reproductively mature, but have not yet fully developed the secondary sexual characteristics of a fully adult silverback (e.g., large body size, sagittal crest, silver hair on their back). They face critical life history decisions, such as whether to remain in their natal group or disperse, or compete immediately versus wait for later mating opportunities. These decisions may have effects on male development and physiology, including the speed at which they acquire secondary sexual characteristics. We know a phenomenon called "bimaturism," (where males can employ different reproductive strategies by maturing at different times) happens in other primates such as orangutans, but does it happen in gorillas as well? This project is led by graduate student Ella Brown.

    High elevation adaptation and climate change

    Non-human primates are losing their habitats at a faster rate than ever before, and with the looming threat of climate change, this is unlikely to resolve itself. Primates living in extreme and variable environments will likely be the most negatively impacted. The Virunga mountain gorilla population living in Volcanoes National Park has adapted to live in cold and wet conditions at a high elevation. We are specifically interested in questions such as, how does the Virunga gorilla population behaviorally and physiologically adapt to this extreme environment?  how do their environmental conditions and stressors vary across the different microclimates they use? how will this population be affected by climate change? It is unclear if the current adaptations used by Virunga gorillas will be enough to survive the predicted warming climate of this region. Therefore, It is important to measure their physiological and behavioral responses as the climate continues to warm, This project is led by graduate student McKensey Miller.

  • Teaching

    Current and upcoming classes at the University of Michigan

    Fall 2022 courses

    Anthrbio 368/Psych 338: Introduction to Primate Behavior

    Anthrbio 569/Psych 539: Grant Writing for Life Sciences

  • Collaborators

    The people and projects we can't work without

  • Science communication

    The Planetary Laboratory

    Current K-12 science teaching practices often limit kids' science exposure to out-of-date materials with little obvious relevance to the world children see around them. The Planetary Laboratory team is working to transport science from field sites, laboratories, and universities, into the classroom. Our NSF-supported project is helping teachers and kids learn how scientists solve problems, and helping scientists reach--and learn from--teachers and kids.

    General interest writing

  • Opportunities

    Current openings in the lab

    Prospective graduate students

    Information about the department and the graduate school application process at the University of Michigan can be found here, but please contact Professor Rosenbaum directly if you are a highly qualified candidate who plans to apply. Feel free to use the contact form at the bottom of this website, or send an email. Priority will be given to students with prior field and laboratory experience, and who have a strong interest in theory-driven questions.

    Research opportunities for undergraduates

    Are you an undergraduate who is interested in getting involved in biological anthropology research at the University of Michigan? See here for more information about what the faculty in our subfield do, and please fill out this form to indicate interest in one or more of our labs. While we do not always have opportunities available, if there is a position we feel is a match for your interests, we will be in touch.

  • Contact