Olivia (pictured middle) died shortly after this photo was taken

So much for the “hippy chimp”. Bonobos, known for their peaceable ways and casual sex, have been caught in the act of cannibalism.

An account of a group of wild bonobos consuming a dead infant, published last month, is the first report of cannibalism in these animals – making the species the last of the great apes to reveal a taste for the flesh of their own kind.

The account comes from a group of primatologists led by Gottfried Hohmann of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The team has studied bonobos in the wild at a site in Salonga national park in the Democratic Republic of the Congo on hundreds of days since 2002. Few were more eventful than 9 and 10 July, 2008.


Early on the morning of 9 July, Andrew Fowler spotted an ape known as Olga with her two daughters: 5 or 6-year-old Ophelia, and Olivia, who was three years her junior. “By 8 o’clock Olivia was dead,” says Fowler. She showed no obvious traces of blood or bruises, so it seems unlikely she had been killed by other members of her group.

Decomposing corpse

Fowler’s team lost sight of the apes not long afterwards, but early the following day he saw Olga join them carrying Olivia’s body, which had already begun to decompose. “It was smelling, limp and wet,” he recalls. Olga and seven others spent the rest of the day devouring the corpse.

“We’ve never seen anything like this,” says Vanessa Woods at Duke University in Durham, North Carolina, who studies semi-captive bonobos at a reserve. “The last time I saw an infant die, the mother held onto it for days and the keepers had trouble taking the body away.”

Though bonobos mostly eat fruit and leaves, they are known to hunt monkeys and the small antelopes called duikers. But Fowler noted signs that this meal was somehow different. More individuals got a taste of the infant than is typical when the apes share meat. They also spent 7½ hours eating the body – longer than they take over a similar-sized monkey. Some even played with it. “If they just think of it as another piece of meat, why do they behave differently with it?” he asks.

Needing nourishment

Fowler warns against over-interpreting the event, and reckons that the need for nourishment was the animals’ main driver. “If you eat meat and you can see [the infant] as a reasonably large piece of meat, you may as well eat it,” he says. “It’s perfectly normal that you would eat the meat that’s available, even if it’s in the form of a dead infant.”

Frans de Waal at Emory University in Atlanta, Georgia, agrees. “It may be that bonobos are craving animal proteins and fats more than we realise.”

There are fewer opportunities to study bonobos in the wild than chimpanzees, and it is impossible to tell from this one observation whether cannibalism is a regular feature of their behaviour. David Dellatore, a primatologist at Oxford Brookes University in the UK, who last year became the first to document an instance of cannibalism in orang-utans, doubts it. “In all of the great apes except for the chimpanzee, all documented cases of cannibalism are outliers,” he says.

When primates eat their own

Chimpanzees: Of all the great apes, chimpanzees resort to cannibalism most often. Typically, males will kill and eat the infant of another female, usually in their own group but occasionally in another. When chimps kill adults from other groups in a fight, they do not eat the body.

Gorillas: In the 1970s, primatologist Dian Fossey found remains of two gorillas in the faeces of a mother gorilla and her daughter. Nothing has been reported since.

Orang-utans: Two instances of cannibalism have been documented in orang-utans living wild in Sumatra. In both cases, the mothers ate their infants after carrying their corpses around for several days. David Dellatore of Oxford Brookes University in the UK, who observed both events, thinks they were due to stress.

Humans: Cut marks on 800,000-year-old hominin remains from Atapuerca, Spain, and more recent fossilised Neanderthal bones suggest that our distant ancestors ate the flesh of their own species. More recently, thousand-year-old bones discovered in the American Southwest bear clear signs of butchery. There are even signs of cannibalism in the human genome: a mutation has been found in Papua New Guineans that protects them from kuru, a prion disease transmitted through cannibalism.

Journal reference: American Journal of Primatology, DOI: 10.1002/ajp.20802