Research Projects

We all know the importance of eating right if we hope to maintain a healthy body weight. Far fewer realize that whether we develop a condition like obesity is also partly a response to our mother’s eating habits when she was pregnant with us. Similarly, how we react biologically to stress was partly “learned” in utero in response to our mother’s experiences of stress during pregnancy. These are but two examples of how early environments can permanently alter, or “program”, biology by modifying the development of organs, tissues, and physiologic systems.

These developmental processes are the subject of a rapidly growing focus in biomedical and public health research. They also hold fascinating insights for anthropological problems like the causes of human variation and the modes of adaptation. Why might our bodies alter biological settings in response to experiences prior to birth? Is this merely a limitation of the developing body’s capacity to buffer itself against disruption? Alternatively, given that the fetus receives a stream of hormones and nutrients from the mother, might these allow it to set up certain biological parameters, such as energy expectations, in anticipation of the environmental conditions that it is likely to encounter after birth? Variations on this hypothesis have been proposed to explain patterns of disease in populations experiencing rapid changes in diet, culture and lifestyle: in these settings, individuals who were undernourished in utero but go on to experience more abundant nutrition as adults are often at greatest risk for diseases related to obesity.

Developmental programming of adult health in the Philippines. Much of my work has evaluated the long-term effects of early environments in the Philippines, a nation experiencing rapid changes in diet, lifestyle, and disease. Since 1998, I’ve worked with US and Filipino colleagues on one of the few studies in a non-western setting capable of clarifying the biological effect of early environments with longitudinal data extending back to pregnancy. Our research shows how the nutritional and lifestyle changes underway have more adverse effects on CVD risk among individuals who were born small or whose mothers were marginally nourished during pregnancy. As a continuation of this focus, we currently have grant support to assess the prenatal and early life determinants of weight gain and CVD risk in all mothers and their young adult offspring (n ~ 4,000).

While developmental programming may contribute to disease transitions in nations experiencing rapid change, a lifecourse, intergenerational model could also help explain health disparities in other contexts, like the cluster of perinatal and adult conditions found among African Americans.

A developmental approach to male reproductive ecology. If the fetus uses nutritional cues conveyed by the mother to adjust future nutritional requirements, we should expect expenditure on energetically costly but non-essential traits to be diminished in response to early life nutritional stress. In males, these prominently include sexually dimorphic traits like stature growth and muscle, which in part reflect the anabolic effects of testosterone. Several grants are allowing us to evaluate plasticity in male life history and reproductive ecology in the Philippines. This research will clarify the effect of early environments on the hypothalamic-pituitary-testicular axis and its regulation, including production of both testosterone and sperm, and any downstream effects on energetically-costly, testosterone-sensitive traits like muscle mass, stature, and strength.

Evolutionary medicine. Public health can clarify how it is that we get sick, but leaves open the broader question of why we get sick. From an evolutionary perspective, diseases like obesity and diabetes can be viewed as a result of the body’s strategy for prioritizing and allocating its finite energy. I am particularly interested in the importance of the brain to the body’s energy budget during infancy: not only does the brain demand most of the body’s energy at this age, but it is quickly damaged if this supply line is even temporarily disrupted. The challenge of feeding the brain is compounded by the frequent nutritional disruptions that accompany weaning and childhood infectious diseases. I have argued that this confluence of factors helps explain why our highly-encephalized babies also come equipped with more body fat than any other mammalian neonate. I also believe that some of the changes in metabolism and physiology triggered in response to early life nutritional stress, such as we see in the Philippines, might be understood as a strategy to buffer the fragile and energy-hungry brain at this nutritionally-turbulent age.

The synthesis of evolutionary and developmental biology. The bringing together of Mendel’s laws with Darwin’s principle of natural selection in the 1930s and 40s laid the foundation for modern evolutionary biology. These developments, described as the Modern Synthesis, revealed how the differential replication of genes could create complex adaptations like eyes and wings. As an accident of scientific history, the rules that govern how genes unfold and interact with the environment to actually create such traits—developmental biology—were largely missing from this synthesis. As a result, developmental processes were relegated to a black box and their role in evolution taken for granted for much of the 20th century. The brisk pace of research on developmental plasticity, epigenetic inheritance, life history evolution, and the genetics of developmental pathways (evo-devo) is helping finish the important work begun 80 years ago by bringing development back to the center of the field. As a student of evolutionary biology and its history, I have a keen interest in this new synthesis and the contribution that anthropologists can make to it.