Department of Anthropology | University of Michigan
I am a behavioral ecologist who studies the evolutionary causes and consequences of social behavior. My empirical work to date has primarily focused on a wild population of mountain gorillas in the Great Lakes region of Africa. This population has been monitored for 50 years, which provides unparalleled opportunities to understand how variation in ecological and social environments influences reproductive success and life history patterns in a long-lived mammal. I use behavioral, genetic, and hormonal data to determine how kin discrimination, behavioral plasticity, and life history decisions interact to produce the astonishing range of variation observed in these animals’ social group structures and social relationships. The goal of my research is to gain a richer understanding of the evolution of mammalian sociality generally, and the hominid lineage specifically.
In addition to my research on gorillas, I also work on complementary research questions about primate evolution, sociality and health, using the Cebu Longitudinal Health and Nutrition Survey (humans), and data collected for the Amboseli Baboon Project (savannah baboons), via collaborations with Dr. Christopher Kuzawa at Northwestern University, and Dr. Beth Archie at University of Notre Dame.
You can find a copy of my CV here.
Humans and many other animals develop myriad social relationships across the course of their lifetimes. I study how these relationships develop and are maintained, what their consequences are for participants, and how individual relationships impact evolutionary dynamics.
Social relationships have many physiological correlates. For example, hormones and social behavior work in complex feedback loops. I study how relationships and physiology impact one another, and how their interactions affect health, longevity, and reproductive success.
Studying wild primates, especially critically endangered species, comes with many methodological challenges. I work on improving existing tools, and developing new ones, to non-invasively measure a variety of physiological parameters.
Peer Reviewed Publications
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.
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.
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.
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 (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.
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, 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.
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.
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.
Rosenbaum S, Vecellio V, & Stoinski TS (2016). Observations of severe and lethal coalitionary attacks in wild mountain gorillas. Scientific Reports, 6, 37018.
Eckardt W, Stoinski TS, Rosenbaum S, Umuhoza MR, & Santymire R (2016). Characterizing stress physiology in Virunga mountain gorillas. Conservation Physiology, 4, cow029.
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.
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
In Review or Revision (available upon request)
Rosenbaum S, Eckardt W, Stoinski TS, Kuzawa CW, & Santymire RS (in review). Group structure, but not dominance rank, predicts fecal androgen metabolite concentrations of wild male mountain gorillas (Gorilla beringei beringei).
Rosenbaum S, Kuzawa CW, McDade TW, Avila J, Bechayda S, & Gettler LT (in review). Fathers’ care in context: evaluating the importance of alloparental care, paternal labor and education, and family structure to paternal care in Cebu, Philippines.
Rosenbaum S & Silk JB (in review). Pathways to paternal care in primates.
Zeng S, Rosenbaum S, Archie EA, Alberts SC, & Li F (2020). Causal mediation analysis for sparse and irregular longitudinal data. arXiv preprint: https://arxiv.org/abs/2007.01796
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.
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.
Special theme issue of Physiology & Behavior: Evolutionary perspectives on non-maternal care in mammals: physiology, behavior, and developmental effects.
In most mammal species, only mothers care for young. However the exceptions, including humans, are of particular theoretical importance for our understanding of the evolution of sociality and of reproductive strategies. Lee Gettler and I co-guest edited a special journal issue on the physiology and behavior of non-maternal caretaking in mammals, The issue contains a wide variety of empirical, theoretical, and review/synthesis papers from diverse fields, including neurobiology, psychology, anthropology. You can find the link to the full issue here.
Evolutionary consequences of socioecological novelty
Mountain gorillas are a rare conservation success story, and their growing population has brought increased inter-group contact, potentially evolutionarily-novel group structures, and expansion into new, higher-elevation habitat. I am working with Drs. Tara Stoinski, Rachel Santymire, and Winnie Eckardt to understand how the animals respond to socio-environmental novelty, and use this to generate data-driven hypotheses linking emerging conditions to evolutionary outcomes at the individual, group, and population levels. In addition to its clear theoretical implications, especially in a world where virtually all organisms are experiencing the effects of rapid anthropogenic change, this research has immediate conservation implications for endangered mountain gorillas.
Social behavior, adaptive response, 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. Initially, I am focusing on the Amboseli baboon population, in collaboration with Dr. Beth Archie. 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, I am writing a series of papers that explore how steroid hormones are related to intra- and inter-individual variation in male reproductive strategies, including caretaking. Across the two species, these papers address 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.
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. I am part of The Planetary Laboratory team, which 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.
Current openings in my lab
Prospective graduate students
I am always happy to hear from potential graduate students or postdocs. Information about the department and the graduate school application process can be found here, but please contact me directly if you are a highly qualified candidate who plans to apply. Priority will be given to students with prior field and laboratory experience, and who have a strong interest in theory-driven questions.