omedical research, and my work in Samoa
represents a first step in exploring the social ecology of stress and immunity
in a non-western setting. However, additional factors are important
determinants of immune development and function, and I have been working
toward a more comprehensive analysis of the developmental ecology of human
immunity through ongoing field research in the Philippines and Bolivia.
The Cebu
Longitudinal Health and Nutrition Survey (CLHNS) is an ongoing study
of maternal and child health in the Philippines, and I have been using
this dataset to evaluate the long-term effects of prenatal and early postnatal
environments on adolescent immunocompetence. By analyzing blood samples
from Filipino adolescents for 3 aspects of immune function (thymic hormone
levels, antibody response to typhoid vaccination, total IgE concentration),
and relating these results to data collected while these adolescents were
infants, we were able to show that the ecologies of nutrition and infectious
disease experienced in utero and in early infancy have long-term effects
on immune function. Publications from this work were the first to
document evidence of early “programming” of the immune system—a process
that may have significant implications for current understandings of adaptation
and human development.
Complementary research in lowland
Bolivia is exploring the ecology of immune function, infectious disease,
and child growth among the Tsimane’, a relatively isolated Amerindian population.
The Tsimane’ are at the earliest stages of cultural and economic transition,
and provide a unique opportunity to investigate the local implications
of globalization. In addition, they represent an interesting contrast
to my earlier work in Samoa, where engagement with western lifestyles had
been occurring for decades. Laboratory and data analyses are currently
ongoing, but preliminary work indicates that high burdens of infectious
disease (as measured by a biomarker of immune activation, C-reactive protein)
likely contribute to growth faltering among Tsimane’ children, and that
erosion of local ethnobotanical knowledge associated with acculturation
may undermine child health.
Through my research in Samoa,
the Philippines, and Bolivia I have attempted to demonstrate the importance
of population-based research on human immune development and function in
a wide range of cultural and ecological settings. Recent review articles
construct a foundation for this effort: My Yearbook paper draws on
life history theory to generate testable hypotheses regarding the tradeoffs
associated with investment in immunity versus other critical life history
functions involving growth and reproduction, and to propose an explanation
for the anomalous developmental trajectory of human immune tissues.
My Annual Review article builds on this analysis by attempting to integrate
physical as well as social factors shaping immune function for a more comprehensive
cultural ecological perspective on human immunity. Both these articles—as
well as earlier review papers on immune function and breastfeeding—reflect
my interest in developing theory-based conceptual models to guide future
research into the biocultural ecology of human health.
Relevant publications*
McDade,
T.W., Leonard, W.R., Burhop, J., Reyes-García, V., Vadez, V., Huanca,
T. and R.A. Godoy (in press). Predictors of C-reactive protein
in Tsimane’ 2-15 year-olds in lowland Bolivia. American Journal
of Physical Anthropology.