Image makeover: A five year study of bonobos in the Democratic Republic of Congo observed them hunting other primates on at least five occasions. Credit: Wikimedia
SYDNEY: Unlike the male-dominated society of the chimpanzee, bonobo society – in which females enjoy a higher social status than males – has a ‘make-love-not-war’ kind of image, but this may be all wrong new observations suggest.
The bonobo (Pan paniscus) formerly known as the pygmy chimpanzee, lives only in the lowland forest south of Africa’s river Congo, and, along with the chimp is our closest living relative.
Bonobos are perhaps best known for their promiscuity: sexual acts both within and between the sexes are a common means of greeting, resolving conflicts, or reconciling after conflicts.
Male dominance and bonding
While chimpanzee males frequently band together to hunt and kill monkeys, the more peaceful bonobos were believed to restrict what meat they do eat to forest antelopes, squirrels, and rodents.
But a study published this week in the U.S. journal Current Biology now offers the first direct evidence of wild bonobos hunting and eating the young of other primate species.
“These findings are particularly relevant for the discussion about male dominance and bonding, aggression and hunting – a domain that was thought to separate chimpanzees and bonobos,” said study co-author Gottfried Hohmann of the Max-Planck-Institute for Evolutionary Anthropology in Leipzig Germany.
In chimpanzees, male-dominance is associated with physical violence, hunting, and meat consumption, said Hohmann. “By inference, the lack of male dominance and physical violence is often used to explain the relative absence of hunting and meat eating in bonobos.”
Finger of blame
However, his team’s observations now suggest that these violent behaviours may also exist in ape societies that are not dominated by males.
The researchers made the discovery that the free-loving primates hunt and kill other primates while they were studying a bonobo population living in Salonga National Park, in the Democratic Republic of Congo.
Although the team had prior anecdotal evidence for monkey hunting by bonobos, it came from indirect studies of faeces samples; one of which contained the digit of a black mangabey. Yet, in the absence of direct observation, it was not entirely clear whether the bonobos had hunted the mangabey themselves or had taken it from another predator.
Human implications
Over five years of observation the researchers have now seen three instances of successful hunts in which bonobos captured and ate their primate prey. In two other cases, the bonobo hunting attempts failed.
The data from Salonga National Park showed that both bonobo sexes play active roles in pursuing and hunting monkeys. The involvement of adult females in the hunts (which is not seen in chimps) may reflect social patterns such as alliance formation and cooperation among adult females, they said.
Overall, the experts argue that the discovery challenges the theory that male dominance and aggression must be causally linked to hunting behaviour, an idea integral to earlier models of the evolution of aggression in human and non-human primates.
Hohmann said that future work may shed light on the social and ecological conditions that encourage bonobo monkey-hunting expeditions, yielding insight into the evolutionary significance and causes of aggression in both these apes and our own species.
Alarming decline
Another study published this week in Current Biology reports a drastic decline in the West African sub-species of chimpanzee (Pan troglodytes verus) living in Ivory Coast.
Researchers led by Geneviève Campbell, also of the Max Planck Institute for Evolutionary Anthropology, found that the population had fallen by a staggering 90 per cent since the last survey was conducted 18 years ago.
The alarming decline in a country that had been considered one of the final strongholds for West African chimps suggests that their status should be raised to critically endangered, says the study, which cites a growing human population and civil war as the likely cause of the demise.
The study in Current Biology
