Monday, September 07, 2015

immigrant crises + pan-troglodytic ethology = accelerated musical chairs

pri |  When two groups of chimps bump into each other in the forest, it always leads to conflict. Males threaten each other with loud calls and aggressive gestures. And, occasionally, things escalate to physical violence and warfare.

"If they can grab a member of the other community, they may beat on them, bite them, and continue doing so until they're very severely injured or killed," says Wilson.

(See this video for an example of inter-group conflict among chimps. It was recorded by Wilson's colleague in Tanzania, in 1998.)

He says it makes sense chimps defend their territories. Several studies have shown that a bigger territory means more food for the group, and a better chance of survival.

But if chimps say anything about our own evolutionary past, so do bonobos. They're a smaller species of apes, also closely related to us.

Primatologist Frans de Waal of Emory University has studied what happens when two groups of bonobos encounter each other.

"They have initial hostility, but then they have sex, and they groom, and very soon it looks more like a picnic than like warfare between them," says de Waal.

No one really knows why bonobos are friendlier than chimps. It could be because bonobos live in forests with more food and therefore don't need to protect their resources from neighbors, de Waal speculates.

So what do we make of our primate ancestry, when two of our closest evolutionary cousins are so different?