The role of biological and social influences on sex differences in human child development is a persistent topic of discussion and debate. Given their many similarities to humans, chimpanzees are an important study species for understanding the biological and evolutionary roots of sex differences in human development. In this study, we present the most detailed analyses of wild chimpanzee infant development to date, encompassing data from 40 infants from the long-term study of chimpanzees at Gombe National Park, Tanzania. Our goal was to characterize age-related changes, from birth to five years of age, in the percent of observation time spent performing behaviors that represent important benchmarks in nutritional, motor, and social development, and to determine whether and in which behaviors sex differences occur. Sex differences were found for indicators of social behavior, motor development and spatial independence with males being more physically precocious and peaking in play earlier than females. These results demonstrate early sex differentiation that may reflect adult reproductive strategies.
BBC - Earth - Do bonobos really spend all their time having sex?
By Colin Barras. Humans, meanwhile, show a variety of mating behaviours but often form monogamous couples. Michael Jensen-Seaman and Scott Hergenrother at Duquesne University in Pennsylvania think that it is the chimps — not humans — that have experimented with new sexual behaviours since our lineages diverged. But did male chimps inherit their mating plugs from the last common ancestor they shared with us or did they evolve it later? They found that the enzyme is four times as abundant in human semen as it is in chimp semen. The change is related to the way the ACPP gene is turned on and off. For clues about whether the human-chimp ancestor had similar levels of the enzyme to humans or chimps, the team turned to gorillas.
These apes supposedly have inordinate amounts of sex and never fight. Can this appealing story really be true? Reputation: Bonobos are miniature, sharing, caring chimps, living in hippie communes with no aggression and lots of sex. Reality: Not really.
Though chimpanzees and humans share about 99 percent of the same DNA, numerous physical and behavioral traits separate us from our closest living relatives. But are we different even when it comes to sex? Just how do chimpanzees "do it?