Doctoral Dissertation Research: Social and ecological influences on brain anatomy

Some of the most defining features of primates, including humans, are their large brains and complex social systems. Comparing brain structure – or neuroanatomy – across primate species that live in a wide variety of social organizations can suggest how the brain and sociality are related. Previous studies of primate brain evolution have not included the full extent of social diversity in primates, limiting the conclusions that can be drawn from them. This Doctoral Dissertation Research project combines existing data on neuroanatomy and hormone receptor distributions in the brain from well-studied mammal species and generates new data from species not previously included in prior studies, to better understand how these traits relate to sociality. Beyond sharing data with the scientific community and providing educational opportunities for K-12 students, generating the results from this study allows for advanced training of undergraduates. Hormones, such as testosterone, estradiol, oxytocin, and vasopressin act in the brain, and must bind their receptors to exert any effects on behavior. In rodents and some primates, the distributions of these hormone receptors in the brain are linked to differences in social behavior; however, previous work from a sample of lemur species shows that the patterns may not be the same across all mammalian species. This project expands prior work through three main objectives: 1) to characterize neuroanatomy in thirteen lemur species and broadly compare it to that of better-studied mammalian species, including rodents and other primates, 2) to investigate sex differences in lemur neuroanatomy in relation to androgen and estrogen receptor expression and variation in female aggression, and 3) to explore the relationship between oxytocin and vasopressin receptor distribution and social bonding. Understanding the neuroanatomical and neuroendocrine correlates of sociality in these unique primate species can advance our knowledge of primate brain evolution, and the interplay between the brain and social behavior more broadly. 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.