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Tuesday, June 29, 2010

Chimpanzee behavior and their killer instincts


Killer instincts

Like humans, chimpanzees can engage in guerrilla warfare with their neighbours. As with humans, the prize is more land
Jun 24th 2010
Economist

PEOPLE are not alone in waging war. Their closest living cousins, chimpanzees, also slaughter their own kind—in brutal attacks that primatologists increasingly view as strategic, co-ordinated assaults rather than random acts of violence. But however tempting it is to see these battles through the lens of human warfare, the motives for chimp-on-chimp violence are poorly understood. In particular, researchers have long debated whether the apes fight for land, or for females.

A report just published in Current Biology may help to settle the question. The study it describes, led by John Mitani, of the University of Michigan in Ann Arbor, is the first to offer a detailed picture of organised conflict between chimpanzees. Drawing on a decade of observations in the field, it concludes that, as with human conflict, wars between chimpanzees are fuelled by territorial conquest.

Between 1999 and 2008 Dr Mitani and his colleagues shadowed a group of chimpanzees called the Ngogo, who live in the Kibale national park in Uganda. Most of the time, the Ngogo chimps were anything but model soldiers—squabbling, foraging and lolling about their domain. But on 114 occasions Dr Mitani’s colleague Sylvia Amsler watched large groups of males strike out on silent, single-file patrols to the fringes of their territory.

These forays often turned violent. All but one of the 18 fatal attacks Dr Amsler witnessed occurred during boundary patrols. In each case, males colluded to kill chimps from a neighbouring group.


The territorial imperative

To understand what motivated this violence, the researchers looked at which chimps were actually attacked. If the purpose of chimpanzee warfare were either rape or the abduction of mates, then the expectation would be that adult males would be the targets of lethal violence. On occasion, they were. But most victims were juveniles, and of both sexes.

Furthermore, chimpanzee mothers were often beaten as the raiders snatched and killed their offspring. Though these assaults on mothers were rarely lethal, patrolling chimps were clearly more likely to batter females than recruit them as mates, suggesting that other motives might drive their violent behaviour.

The researchers therefore asked whether geography offered a better explanation. Using the Global Positioning System to map patrol routes and attack locations, they saw that the Ngogo chimps’ reconnaissance fanned mainly beyond their north-eastern border, encroaching onto the land of a neighbouring group. Almost all of the killings occurred in this disputed territory, which sported particularly fine stands of the chimps’ favourite fruit-tree. By the time the study ended, the Ngogo group’s campaign had displaced its rivals completely, annexing the north-eastern lands and enlarging its range by 22%.

Though the territorial upgrade may eventually attract new mates, none of the displaced females has been spotted joining the Ngogo group. This suggests that real estate, not a tight mating market, is the true motive for chimp combat. Such motivation makes sense in the context of the discovery in 2004, by Jennifer Williams of the University of Minnesota, that larger territories enabled chimps in neighbouring Tanzania to produce more offspring. This provides an evolutionary incentive for the apes to expand their range—and its associated resources—by any means necessary.

Can chimpanzee skirmishes tell people anything about their own violent tendencies? One lesson, which may surprise cynics, is that humans are more peaceful than chimps. The rate of killing Dr Mitani reports is between one-and-a-half and five times that seen in human agricultural societies—and between five and 17 times higher than attrition due to warfare among hunter-gatherers, who could have less need to defend territory than farmers. (It is also, it must be acknowledged, higher than that reported for other chimpanzee communities, suggesting that the Ngogo troop may be exceptionally bellicose.) In the context of comparisons with humans, though, the most salient feature of chimpanzee combat may be its co-operative nature.

Chimps avoid single combat. To fight successfully, they must maintain complex, collaborative social networks—suggesting that only by bonding within groups can chimps engage in violence between such groups. This has big implications. It may be the ability to form bonds with strangers was forged by the demands of war. Thus, the human tendency to coalesce around abstract concepts such as religion or nation, which underpins civilisation, may well be an evolutionary legacy of a violent past. Signs of anything similar in a species that, albeit a close-ish relative, parted company from the line leading to humans at least 5m years ago are therefore interesting.

Unfortunately for the chimpanzees of Kibale, they are not the only combatants locked in a central African territorial dispute. Even as bushmeat poachers, exotic-pet traders and encroaching farmers have landed the quarrelsome primates on the endangered-species list, decades of resource-driven conflicts between humans have destabilised conservation efforts. On June 21st, in an attempt to protect chimp populations, the Wildlife Conservation Society of New York and the International Union for Conservation of Nature announced a new conservation plan for the species. By identifying the areas most in need of protection, researchers hope to preserve the culture of chimp communities such as the Ngogo for future study.


12 comments:

  1. Trouble is how it fit in altruism which seems to have an usefullness for the individual, or even the group.

    But as, Berkley, Hume, Kant , Schopenhauer can began see. and came up with an possible answer, with an answer, same as the east, there might be a little 'leak' from the one world to the other is. In the noumenonal there ought not be diffisions, all is at aon, peace, and there is nothing to fight for, while in the phenomenal is just seems so. The 'ought' is there are strongly as the is.

    mee',mi

    (bob fell asleep)

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  2. I'd ratther have bob taking care of my medical carn than Obana, seems to me the likes of us bob treats me like one of his own, with Obama I'm going to end up at the end of some dirty hall somewhere, amongst the dust mops.

    mee'm'

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  3. More about McChrystal.

    Trish,

    Don't mean to beat a dead horse.

    ...Much.


    .

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  4. Funny story. Sort of..

    I was out in the parking lot the other day bs'ing with another denizen of the compound.

    I was talking about that special 2%; strawberry blondes...

    Guy I was talking with is broken down like me. But a player in his day. Unlike me.

    Anyway he excuses himself, ducks back into his hidey hole and comes out with an old pic of a birthday celebration with his 4 ex wives...

    The show stopper was a 6' strawberry blonde...

    He'd met her peddling small arms and had a photo of her on the range...

    Only woman on the line. Standin' tall with those Emmylou gramma jeans... Holster high on her waist...

    My neighbor spoke of a couple of trips with her. How she dealt with a couple of "shady characters" that accosted them one time.

    Said she worked for the State Department.

    Often went off for a month or more at a time...

    Said that, as well as he knew her, there was a side of her he knew he'd never know...


    .

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  5. gnossos, you'll appreciate the next post.

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  6. Stan wasn't just a Ranger. He was a life-long Operator.

    I'd thought a couple of times about doing a partial disclosure of my own husband's working relationship with the man, but decided it would serve no good purpose. It'd just draw more blind fire.

    Stanley McChrystal didn't intend to get himself shit-canned and throw the higher headquarters and the mothership into turmoil, that's for sure. Nothing could have been as painful as having to clear his cubby, so to speak, in Kabul. And turning that wretched mess over to Dave Petraeus, whose wife was undoubtedly heaving a deep sigh over that phone call.

    In any event, that sad episode is behind us.

    Remains to be seen if Team Obama really learned anything.


    On another subject:

    6' tall?

    She has a few inches on me.

    And the last time I went to the range, in Bogota - really just to keep my husband company for the day - I was as previously more or less inept with the Sig Sauer, I think it was; pretty good with the AK and M4; and, look, who cannot get the job gun with a shotgun?

    We actually qualified together down in Fredericksburg before we before we left for Colombia. A sweaty, frustrating week I'd not like to repeat, except for the driving portion, which was outstanding fun.

    4 ex wives? Jesus. Some people do know how to go through them.

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  7. "as well as he knew her, there was a side of her he knew he'd never know..."

    I am completely familiar with this and it's only ever once bothered me. I said so and he responded sympathetically. "What do you want to know?"

    And for whatever reason, I decided I didn't *really* want to know.

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  8. "...only ever once..."

    Well, that's not quite true.

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  9. This comment has been removed by the author.

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  10. Let me try that again:

    Why, oh why, do I always feel like Gracie in George Burns and Gracie Allen?

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