Pregnant bonobos get a little delivery help from their friends

Like humans, African apes called bonobos may treat birth as a social event with a serious purpose.

In three recorded instances in captivity, female bonobos stood close by and provided protection and support to a bonobo giving birth to a healthy infant. Female bystanders also gestured as if ready to hold an infant before it was born, or actually held one as it was born, scientists report online May 9 in Evolution and Human Behavior. Ethologist Elisa Demuru of the Natural History Museum of the University of Pisa in Italy and colleagues filmed these incidents in 2009, 2012 and 2014 at two European primate parks where the apes roam freely through forested areas.

These observations, along with a 2014 report of wild bonobos behaving similarly, challenge an influential idea that human females, unlike other primates, receive birth assistance. Scientists had proposed that the perils of passing a baby through the relatively narrow human birth canal called for help from others. But bonobos can safely give birth on their own, so something else is at work here, Demuru and colleagues suspect. Comparably high levels of sociability among female bonobos and among women may instead explain why helpers assemble as a pregnant individual nears delivery.

Chimpanzees, close cousins of bonobos, are a different story. Female chimps are more competitive and maintain weaker social bonds than female bonobos or humans do. No chimps have been spotted helping or hanging out near a peer about to give birth.

Research on birth practices in wild and captive ape communities remains in its infancy, the investigators say.