Of all of the tactics men take to find a girlfriend and eventually get laid, hanging around with his mother isn’t one of the most popular. Well, there is that Dungeons and Dragons crowd that choose to live life in the basement of the home they were raised in, but the technique isn’t really all that successful when it comes to bringing a girl home.
Or so I’ve heard. I don’t have firsthand knowledge. No, seriously. I don’t.
Though it may not work so well for people, a new study from the University of Wisconsin shows that it does work for at least one species of primates that have no dominant male social structures. The primates I’m speaking of are the critically endangered muriqui monkeys that live only in the Brazilian Atlantic Forest. There’s only about 1000 of these monkeys left, and this study involves nearly one-third of them.
Karen B. Strier took the torch of a study that has been following and observing this society of monkeys since 1983 and added a bit more than observation to the data set. She took a generation of offspring and sequenced the DNA of 22 infants, their 21 mothers and the 24 adult males that potentially could have been their fathers.
In case you’re wondering, the genetic data was taken by getting samples of their poo. What a life.
In many primate societies, a clear hierarchy exists where the dominant males get more food, more respect and more women. In these groups, dominant males can sire as much as 85% of the offspring, with several species well above the 66% line. But in Northern muriqui, there are no dominant males, society is more or less egalitarian, and the most successful male sired just 18% of the newborns (for you math wizards, that’s four of them).
Interestingly enough, however, another aspect of their culture seems to influence the ones that do have the slight edge in reproducing. Because the group has been watched and studied for so long, the researchers were able to notice that the males that maintain close contact with their mothers rather than striking out on their own into new groups have a slight edge in making babies.
There are two reasons that hanging around their mothers might help the Northern muriqui procreate. The first is opportunity. Think of it this way. If you live in the same city as your mother and go visit her in social situations on a regular basis, there’s at least some chance that her shopping buddy is going to have a hot daughter. Voila! Instant access and credibility.
The second explanation goes with the “Grandmother hypothesis” of why human females have evolved to have longer lifespans than males. Once a woman hits menopause and can’t have any more children, they’re still extremely valuable as caretakers and can contribute greatly to the success of the family and the growth of their grandchildren. Thus, the theory is that because grandma likes to spoil you, she’s valuable and thus has been selected to live longer.
With the Northern muriqui, the same theory could hold true. Since older females can help their grandchildren survive and thrive, those that have close ties and live in close proximity with them have a greater chance of siring offspring.