The Human Behavior and Evolution Society (HBES) is meeting at California State University, Fullerton. There are 450 evolutionary psychologists in attendance [Notes from an evolutionary psychology conference]. I don't think I could be happy there.
One of the attendees is a graduate student named Elizabeth Pillsworth. She studies the evolution of adaptations for avoiding incest. You'll be surprised at what she reports.
The researchers' hypothesis on incest avoidance was that near ovulation, women are motivated to avoid affiliation with male kin (fathers) but not mothers, to avoid the potential costs of inbreeding. Their predictions were that relative to low-fertility days, on high-fertility days women would initiate fewer calls and engage in shorter conversations with fathers, compared to mothers.Isn't that amazing? I can't possibly think of any other explanation. There must be a gene for not talking to your father when you're fertile. I wonder what chromosome it's on?
They had 51 normally-ovulating women (mean age 19.1 years old) provide complete cell phone bills from one month, along with their menstrual cycle information and details about individuals on their phone bill. It turned out that the subjects called their fathers significantly less than their mothers during high fertility days, and when both mothers and fathers called them during high fertility days they spent less time on the phone with their dads than with their moms.
Conclusion: "this is the first evidence of adaptation in human females to avoid affiliation with male kin when fertility is at its highest."
I wonder if there were any controls—like how often the women spoke to their boyfriends, or when mothers called their sons?