Darryl Holman's Research: The Ecology of Breastfeeding
For the past several years, my collaborators Michael Grimes, Kathleen
O'Connor, Eleanor Brindle and I have been investigating the ecology of
breastfeeding in Bangladeshi women. This project began as an
investigation of the determinants of early breastfeeding behavior in
Bangladeshi women (Holman and Grimes 2001). From there, we became
interested in differences among mammalian species in distributions of
the onset of breastfeeding, and how they change for different life
history traits, like the degree of physical and neurological maturity
at birth. Although this question cannot yet be answered (there are no
data for any species except humans), we collected data from the primary
literature on times to initiation of breastfeeding in humans. We
hypothesized that if there were preprogrammed early maternal behaviors
in humans (as suggested in the psychobiology literature), we would
detect it as a statistical mixture of two distributions: one reflecting
preprogrammed behaviors and another reflecting culturally-mediated
behavior. From that investigation we concluded that there is evidence
for a weak effect of preprogrammed early maternal behavior in humans
(Holman and Grimes 2003).
In a related project, we used endocrine and questionnaire data
collected in the Bangladesh study to investigate the effects of
pregnancy hormones on the time to initiation of breastfeeding. We
found that a urinary form of estrogen was weakly associated with time
to initiation of breastfeeding--estrogen concentrations "explained" only
4% of the variation in initiation of breastfeeding (Holman et al.
2004). The relatively weak association, combined with our other
results, suggest that human mothers are largely emancipated from
preprogrammed behaviors directed to the newborn; and, we believe this
makes sense in light of other life history characteristics of humans.
Most recently, we are investigating the determinants of postpartum
amenorrhea and endocrine changes through the resumption of ovulation in
Bangladeshi women (Holman et al. in press).
Holman DJ, Grimes MA, Achterberg JT, Brindle E, O'Connor KA
(in press) The distribution of postpartum amenorrhea in Bangladeshi women
The American Journal of Physical Anthropology. (Also: Working
Center for Studies in Demography & Ecology, University of Washington).
Holman DJ, Grimes MA, Brindle E
and O'Connor KA. (2004) Hormonal correlates for the initiation of
breastfeeding in Bangladeshi women. Hormones and Behavior 46(4):382-391.
Holman DJ, Grimes MA. (2001)
Colostrum feeding behaviour and initiation of breast-feeding in rural
Bangladesh. The Journal of Biosocial Science 33:139-54.
Holman DJ, Grimes MA. (2003)
Patterns for the initiation of breastfeeding in humans. The American
Journal of Human Biology 15:765-780.
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