Four decades of chimpanzee observations reveals the mothers of sons are 25 percent more social than the mothers of daughters, spending about two hours more per day with other chimpanzees than the girl moms did. Researchers believe mothers are giving young males the opportunity to observe males in social situations to help them develop the social skills they'll need to thrive in adult male competition.

Source: Boy moms more social in chimpanzees: Watching adult males in action may help youngsters prepare