An example of that is a study of the effects of bottle feeding. Based on what we know of our evolutionary history, the only reason that a new mother would prematurely cease breastfeeding her infant would be in the case of the infant's death. Bottle feeding had not yet been invented. Consequently, a team of scientists at the Department of Psychology, State University of New York in Albany surmised that bottle feeding mimics this loss, and that mothers who breastfeed would be more likely than average to experience postpartum depression.
The researchers found this hypothesis to hold true in a study of 50 new mothers:
We recently completed a study of over 50 mothers recruited through local pediatric offices at 4–6 weeks postpartum . Consistent with previous reports, we found that those who bottle fed their babies scored significantly higher on the Edinburgh Postnatal Depression Scale than those engaged in breastfeeding. The increased risk of depression among mothers who relied on bottle feeding held true even after we controlled for such things as age, education, income, and the mother’s relationship with her current partner.The authors don't label their study as evolutionary psychology, but as evolutionary medicine, and I commend the emergence of this new discipline. What can it bring to the table, then? The authors conclude that
Bottle feeding practices and hospital procedures that simulate child loss may increase the risk of postpartum depression and fall within a growing number of medical issues that could benefit from an evolutionary perspective.[The paper is published in a journal owned by Elsevier, and is not free. If you want a copy of the PDF, let me know and I will send you one.]
Gallup Jr., G., Nathan Pipitone, R., Carrone, K., & Leadholm, K. (2009). Bottle feeding simulates child loss: Postpartum depression and evolutionary medicine Medical Hypotheses DOI: 10.1016/j.mehy.2009.07.016