Little is known about menstrual cycling in the noncontracepting populations characteristic of human evolutionary history. I report the results of a longitudinal investigation of menstrual cycling among the Dogon, a noncontracepting population of Mali. During menses Dogon women sleep at a menstrual hut. This custom permitted me to continuously monitor virtually all menstruations occurring in a village of 460 people over two years. I use data on menstrual cycling to address three questions about Dogon reproductive ecology: (1) Do women synchronize their menstrual cycles?, (2) What is the function of menstrual segregation?, and (3) What are the causes of variation in the waiting time to conception?. Tests for menstrual synchrony provide no evidence for this phenomenon among Dogon women. Neither the mean difference in menstrual onset dates for co-wife pairs, related pairs, or friend pairs differs significantly from that of age-matched random pairs. Moreover, the number of menstrual onsets per day is consistent with a Poisson distribution so the null hypothesis that women's menses occur at independent times cannot be rejected. These results caution against the assumption that menstrual synchrony is adaptive. Previous hypotheses on menstrual segregation appear to overlook the reproductive significance of menstrual huts. Among the Dogon, menstrual huts may promote confidence of paternity by enabling men to selectively marry women who have recently menstruated. This custom reduces their risk of marrying pregnant women. Given the prevalence of serial remarriage, this risk would otherwise be substantial. If the confidence of paternity hypothesis is correct, it supports the broader argument that the consideration of individual reproductive interests is helpful for understanding culture. From data on menstrual hut visitation, I calculated the waiting times to conception among Dogon women. Using hazard analysis, I then determined which variables are significantly associated with the elapsed time before a woman conceives. Conception waits are significantly associated with age, nursing status, marital duration, and gravidity. I found no evidence for a significant association between conception waits and the following: nutrition, economic status, polygyny, and the length or variability of menstrual cycles.Ph.D.Biological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105290/1/9116303.pdfDescription of 9116303.pdf : Restricted to UM users only
