While we continue collaborations focused on the role of the gut microbiota in shaping non-human primate ecology and evolution, our current research focuses on comparisons between non-human primates and humans as well as investigations of host-gut microbe dynamics in human populations around the world. These projects broadly examine the interactions of host diet, physiology and the gut microbiota. More specifically, we focus on microbial contributions to host nutrition during periods of reduced food availability (e.g. seasonality) or increased nutritional demands (e.g. pregnancy), as well as microbial influences on brain growth.
Here are a few of the ongoing projects in the lab:
Western and Non-Western Diet in Humans and Non-Human Primates
Gut microbes break down dietary starch and fiber to generate short-chain fatty acids (SCFAs), which can be absorbed by hosts and used as an energy source. Differences in dietary fiber intake, as dictated by a Western or Non-Western diet, can lead to changes in the types and proportions of SCFAs produced. As the Western diet has evolved to include higher amounts of processed sugar, heavier dependence on meat, and lower intake of fiber, it is possible our SCFA production has been altered.
Among other factors, human brain expansion is believed to have depended upon a shift in energy allocation from the gut to the brain as well as increased fat stores as a buffer against food shortage. It is possible that gut microbial SCFA production patterns played a role in these physiological shifts, especially given that human evolution is characterized by a gradual reduction in fiber intake. Because it is virtually impossible to recover gut microbial data from our earliest human ancestors, a better understanding of these putative processes depends on comparisons of the human and non-human primate gut microbiota.
Therefore, this project compares SCFA production potential in humans and non-human primates to determine if humans exhibit a unique relationship between diet, the gut microbiota, and physiology. Funded by the Wenner-Gren grant, this study represents a critical first step toward understanding the potential role of the gut microbiota in shaping human metabolic and physiological changes over evolution.
Gut Microbiome of Omnivorous New World Monkeys
Six omnivorous primate species, including large- and small-brained primates, were sampled in South America. With funding by the Leakey Foundation, Dr. Liz Mallott is leading this comparative study with hope it will give a broad context on how omnivorous species look like, more generally. We also hope to gain more insight into the evolutionary trajectory of humans now that we have shifted to a diet with more animal prey.
The Cebu Study
In collaboration with Thom McDade and Chris Kuzawa, we utilize longitudinal data collected from families living in Cebu, Philippines for over 30 years. Using microbiome and biomarker samples, we are investigating life history patterns, fetal growth rate and birth weight, and physiological dynamics during pregnancy. Learn more about the Cebu Longitudinal Health and Nutrition Survey here.
Pregnancy creates additional energy costs for mothers. We are sampling pregnant and non-pregnant females across the world to understand how microbes change during pregnancy in an effort to understand what are the microbial contributions during these times of increased nutritional demands.
Additionally, Melissa Manus is investigating the role of the social environment on the ecology of the developing infant microbiome. We are particularly interested in the role that alloparents play in transferring microbes to infants and what this means for the development of microbial communities at different body sites.