Bond­ing with bono­bosTORY

Peo­ple don’t tend to take bono­bos se­ri­ously, but there’s a lot we could learn from our gen­tle, ma­tri­ar­chal cousins.

BBC Wildlife Magazine - - Contents - By Vanessa Woods Pho­tos Roland Hil­gar­t­ner

Meet the friendly but elu­sive bono­bos that re­side in one of the most re­mote re­gions of the Congo

We have two sets of cousins in Africa. We have many traits in com­mon with both – traits we share with one and not the other, as well as traits that are uniquely our own. You have prob­a­bly heard about our chim­panzee cousins many times be­fore. They are rel­a­tively easy to visit, and there are lots of pho­tos and videos. They of­ten come up in con­ver­sa­tion about evo­lu­tion and how we came to be hu­man.

The other cousins are more of a mys­tery. They live deep in the Congo Basin, in a lu­mi­nous wilder­ness that may be the last of its kind on Earth. These cousins are shy. A long, bloody war in their coun­try made them in­ac­ces­si­ble for decades. But the war is over, and it is time to meet these long-lost rel­a­tives. In­tro­duc­ing bono­bos… at long last.

“To see them for the first time was fas­ci­nat­ing,” says Roland Hil­gar­t­ner, a pho­tog­ra­pher and pri­ma­tol­o­gist. “When they came down from the trees, I was im­pressed by their grace­ful move­ments, how beau­ti­ful they were. Es­pe­cially look­ing into their eyes. It’s not hard to see we are so closely re­lated.”

To get to the bono­bos you must fly into Kin­shasa, the cap­i­tal of the Demo­cratic Repub­lic of Congo. Then you char­ter a plane and fly four hours north into the city of Djoulu, then ride for five hours on the back

of a mo­tor­bike to the vil­lage of Ye­tee, where you must stay for at least one din­ner hosted by the Bon­dango peo­ple, the lo­cal guardians of the for­est. From there it is another hour on foot to Lonoa, the re­search camp named af­ter a river that weaves through the for­est.

Ar­riv­ing at Lonoa is like step­ping back in time. Dwarfed by an­cient trees shoot­ing 30m high, sim­ple huts are wo­ven from what can be found in the for­est. Wash­ing is slung over twine to dry. There's no elec­tric­ity or run­ning wa­ter. Just out­side camp, bono­bos are call­ing.

“I re­mem­ber the fe­males were un­happy with one of the males for some rea­son,” says Dr Martin Surbeck of the Max Planck In­sti­tute of Evo­lu­tion­ary An­thro­pol­ogy. Surbeck is the direc­tor of the Loana re­search site, and one of the world’s few bonobo ex­perts. “They were all shout­ing and scream­ing at him. Sud­denly they turned around and saw me, and de­cided I was the one caus­ing trou­ble. All the fe­males started shout­ing and scream­ing at me. I was scared. Really scared.”

In gen­eral, fe­males have it rough in our pri­mate fam­ily. Chim­panzees males can be very ag­gres­sive to­wards a fe­male, es­pe­cially when she is sex­u­ally re­cep­tive. Males know when a fe­male is ovu­lat­ing be­cause the pink part of her bot­tom swells, ad­ver­tis­ing ex­actly when she is most likely to con­ceive. All the high-rank­ing males at­tack her, beat­ing her into sub­mis­sion so she will mate with them.

The fe­male’s only de­fence is to stay close to the al­pha male as pro­tec­tion. Once she has her baby, if the male loses his sta­tus, the new al­pha may kill her in­fant. This per­pet­u­ates a cy­cle of vi­o­lence, where ag­gres­sive males have the ad­van­tage and in­fan­ti­cide quickly re­turns nurs­ing moth­ers to a re­pro­duc­tive state.

Fe­male dom­i­nance

Bonobo fe­males will have none of this kind of be­hav­iour. They hide their ovu­la­tion with swellings that last for longer, so males can­not tell ex­actly when they are ovu­lat­ing. Also, fe­male bono­bos can be ex­tremely ag­gres­sive to­wards males who start act­ing like chim­panzees. Any male who tries to force fe­males into mat­ing is met with fierce op­po­si­tion – of­ten from a coali­tion of an­gry fe­males. And if any male even looks at a baby the wrong way, they quickly feel the full force of fe­male wrath. Fe­males work to­gether so that even though males might win in terms of size, fe­males al­ways win in terms of num­bers.

“Fe­male bono­bos get away with any­thing,” says Surbeck. “I’ve seen them pull a male’s legs right out from un­der him so he trips over and falls. They think this is so funny.” If this sounds un­ortho­dox – it is. There are some an­i­mals such as hye­nas where fe­males are dom­i­nant to males. But fe­male hye­nas are big­ger than males, with more mus­cles and more male hor­mones, such as testos­terone. Fe­male hye­nas hunt and fight. They even have pseudo-penises. But bonobo fe­males are smaller than males. It is ex­tremely rare for fe­males to dom­i­nate males with­out a phys­i­cal ad­van­tage. Even more un­ortho­dox is how fe­male bono­bos are dom­i­nant.

In chim­panzees, the males mostly so­cialise with other males. They take the best spot in the fruit­ing trees, leav­ing the fe­males to scram­ble for fruit lower down. “In bono­bos,” Surbeck says, “it is mostly the fe­males who are in the best part of the tree. If a male wants to come in he can – if his mother is there.”

The best chance of a male bonobo get­ting ac­cess to fe­males is through his mother. It is his mother who in­tro­duces him to all her friends, and any new fe­male who has ar­rived. Un­like chim­panzees, bonobo males do not at­tempt to dom­i­nate their moth­ers. They achieve all their sta­tus and rank through her. In fact, there are some bonobo ba­bies who out­rank adult males. And even if an adult male is higher rank­ing than a baby, the male is al­ways very well be­haved.

“High rank­ing chim­panzee males have higher testos­terone and cor­ti­sol,” says Surbeck. “In bonobo males it is the op­po­site. The high-rank­ing males have lower testos­terone. They need to stay calm to re­main in the cen­tre of the group with the fe­males. They can’t cause any trou­ble. You wouldn’t want to get kicked out of the tree by Mum.”

You might think that male bono­bos might suf­fer for their un­man­li­ness in terms of re­pro­duc­tive suc­cess. Surbeck cer­tainly did. “I thought, you know, there is a lot of mat­ing, ev­ery­body gets a lit­tle bit of a share, the males don’t fight, so the pa­ter­nity would be more evenly dis­trib­uted.” But when Surbeck looked at pa­ter­nity, it was the op­po­site. The

The best chance of a male bonobo get­ting ac­cess to fe­males is through his mother in­tro­duc­ing them.

Be­ing nice to fe­males, kind to in­fants and sweet to your mum seems to work very well.

high­est-rank­ing bonobo male – the friendli­est and best-be­haved – had most of the ba­bies. As a re­pro­duc­tive strat­egy, be­ing nice to fe­males, kind to in­fants and sweet to your mum seems to work very well.

In most mam­mals, it is the males who leave their mother’s group and find a new com­mu­nity. In bono­bos and chim­panzees, it is the fe­males who em­i­grate. For chim­panzee fe­males, this is the mo­ment where they re­ceive the most ag­gres­sion from other fe­males. The res­i­dent fe­males of the new group at­tack the new fe­male, some­times killing her baby, if she has one. The fe­male im­mi­grant be­comes one of the low­est-rank­ing chim­panzees in the group. She can only seek pro­tec­tion from the males, who will di­rect their ag­gres­sion to­wards her later, when she is sex­u­ally re­cep­tive.

In bono­bos, an im­mi­grant fe­male is greeted with kind­ness and ex­cite­ment. The other fe­males rush to­wards her, com­pete to groom and rub gen­i­tals with her. These res­i­dent fe­males have been seen to de­fend the new fe­male against males they have known for years. Moth­ers have even de­fended new fe­males against their own sons.

This kind­ness seemed to ex­tend to­wards all strangers. Our re­search group played a game with bono­bos at the Lola ya Bonobo sanc­tu­ary in Congo. Say you have $100. There is some­one in the next room, a stranger you have never met be­fore and who you will never see. Then there is some­one in the other room, who is a friend. You can ei­ther share with your friend, share with the stranger, or keep all the money. Most peo­ple usu­ally share with their friend. It makes sense to share with some­one who might re­turn the favour later.

Acts of kind­ness

We played this game with bono­bos, us­ing food in­stead of money. The bonobo in the mid­dle was a bonobo fe­male called Kalina, and we gave her a pile of fruit. She could choose to un­lock the door for ei­ther her friend or a stranger. Kalina opened the door to share with a stranger. Then once the stranger was in the room, the stranger opened the door for the friend, so all three bono­bos could eat to­gether.

When we ran another ver­sion of this ex­per­i­ment where Kalina was not even in the room with the food, she still opened the door for the stranger, even though she did not get any food, and could not play with the stranger once the door was opened. We found that bono­bos would help a stranger, even when there was ab­so­lutely no re­ward.

In chim­panzees, re­la­tion­ships be­tween strangers are fraught with ten­sion. As a male chim­panzee, you are more likely to be killed by a male stranger than by any­one else. Bono­bos have no rea­son to be afraid of strangers; any scuf­fle that might oc­cur is mi­nor com­pared to what is seen in chim­panzees. We found that bono­bos are not only non-ag­gres­sive to­wards strangers, they are at­tracted to them. This at­trac­tion al­lows them to help a stranger in a way we will never ob­serve in chim­panzees.

Only last year, in the wild, bonobo re­searchers Bar­bara Fruth and Got­fried Hohmann saw some­thing in­cred­i­ble. One af­ter­noon, bono­bos from the Bom­pusa West com­mu­nity met up with those from Bom­pusa East. The al­pha male of the Bom­pusa West caught a small an­te­lope. Bono­bos from both

com­mu­ni­ties ap­proached him. He moved into the crown of a tall tree, fol­lowed by nine fe­males ( four from one group, five from the other) and their off­spring. For the next half an hour, he shared meat with ev­ery­one.

When an­thro­pol­o­gist Her­bert Spencer read Darwin’s On the Ori­gin of Species, he coined the phrase, “sur­vival of the fittest”. But over the years, fit­ness was con­fused with phys­i­cal fit­ness, such as size and strength. Cou­pled with the ob­ser­va­tions of vi­o­lence in na­ture, sur­vival of the fittest came to mean that the strong would sur­vive and the weak would per­ish. How­ever, fit­ness is just your abil­ity to re­pro­duce. It was never meant to go be­yond that. Bono­bos have a fit­ness that is al­most cer­tainly unique. Where males treat fe­males like part­ners, where ev­ery­one is wel­com­ing to im­mi­grants and kind to strangers.

“One of the most spe­cial mo­ments was when I was tak­ing a photo of Izia cross­ing the river,” says Hil­gar­t­ner. “She was stand­ing in the river and so was I and she looked at me. She had her baby on her back, and when our eyes met, she was just so hu­man.”

Few peo­ple take bono­bos se­ri­ously. Bono­bos have been cel­e­brated and mocked as the ‘make-love-not-war’ hip­pie ape. They are of­ten ig­nored as a freak­ish rel­a­tive best left in the closet. But we ig­nore bono­bos at our peril.

All fe­males pre­fer males who are less ag­gres­sive. But only bonobo fe­males have man­aged to turn this pref­er­ence into a choice. And their choice is for tol­er­ant males, who de­spite their size and strength, are still of­ten sub­mis­sive to a baby. In our large fam­ily of primates – and our even more close-knit great ape rel­a­tives – bono­bos stand alone. Bono­bos have es­caped the lethal vi­o­lence that threat­ens the rest of us. They do not kill each other. And that is a feat, that de­spite our in­tel­li­gence, we have not yet man­aged to ac­com­plish.

FIND OUT MORE

Dis­cover more about the Bonobo Con­ser­va­tion Ini­tia­tive at: bonobo.org

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