Group comparisons exemplify population differences in the relative importance of determinants of fertility. Also, our findings among Kami do not support reported associations between increasing maternal age and a less responsive neuroendocrine system since maternal age is positively associated with PRL levels. Our findings suggest that in the case of Kami, age-related behavioral modifications are more likely to underlie the association between maternal age and PRL levels than physiological changes. Varying levels of parental care, or investment in offspring, are reflected in variations in population sex ratios and infant mortality and morbidity rates. These contexts provide supports and constraints that influence parental attributes.
Behavioral data based on interactions with their own infants are also part of the study.
Heart rate responses are evaluated as an indicator of autonomic response to infant cues. The overall aim of the study is to contribute to a normative understanding of the biological and social mediators of parental behavior, and by extending the focus to fathers and non-parents, explores whether responsiveness is different according to sex and parental status. Final analyses are underway and data are being prepared for publication. Also, fathers with lower testosterone levels have higher baseline heartrates and heartrate responses to cries, whereas mothers exhibit a positive correlation between cortisol levels and heartrate at baseline and in response to cry stimuli. American Journal of Physical Anthropology , Suppl.