Women of the same age spend a lot more time and effort talking to each other one-on-one using voice, text and email than men, who used the phone far less and tended to bond in groups during activities rather than conversations.
Women's phone records showed "intense, one-on-one friendships maintained and shaped through frequent communication."
Their conclusion was that women's networks weren't only about friendship and mutual emotional support. They were focused on choosing, developing and maintaining the women's romantic relationships.
'Hen party' or Committee on Evolution of the Species?
Those focused discussions amount to a cooperative analysis of the prospective mates for each woman and the best way to go about choosing a mate.
That complex analysis plays much the same role in humans that mating displays or battles for dominance among males do among other animals, the paper concludes.
Rather than judging males on the redness of a baboon butt or size of the rock nest built by a hopeful penguin, human females judge prospective mates using a complex analysis of their physical appearance, social skills, potential for growth in social and financial circumstances, emotional aptitude and compatibility and other factors.
Hence, women in their 20s and 30s define the social requirements for both sexes of the same age, largely through decisions reached through long discussions and consensus among a network of female friends, often advised or guided by women over 50 providing advice.
Men, whose volume of phone conversation doesn't peak until 32, rather than 27 in women, appear to be separate from this process during their 20s, but gradually accede to it in order to form long-term pair bonds of their own.
"We have been able to demonstrate striking patterns in mobile phone usage data that reflects shifts in relationship preferences as a function of the way the reproductive strategies of the two sexes change across the lifespan," researchers concluded. "We have been able to demonstrate a marked sex difference in investment in relationships during the period of parbond formation, suggesting that women invest much more heavily in pairbonds than do men. Though previously suspected, this suggestion has been difficult to test."
So, if you're one of those people others hound about talking too much on your cell or texting while they'd prefer you pay attention to them, now you have an answer: you're not gossiping or wasting time. You're guiding the path of human evolution and developing the rules that govern how members of a society should conduct themselves and specifically why, given the application of the right criteria, men can be demonstrated scientifically to be complete jerks.