Thursday, June 22, 2017

The Value of Territorial Aggression for Chimpanzees #Science #Ethology

A primate named Wilson and his cohort jointly test the boundaries of their group's region. 

Credit: Kevin E. Langergraber

Make no mistake of the danger of chimpanzees since they're substantially stronger than men and they coordinate their attacks.  You are doomed, Jungle Jim.

If this recalls Robert Ardry, Desmond Morris, or others, it's deliberate since the study of aggression in ethology and primatology specifically shows significant parallels so we believe there are lessons to be learned from them.

Territorial boundary patrolling by chimpanzees is a striking example of group-level cooperation displayed by our closest primate relatives.

Chimpanzees patrol in groups for the same reason wolves hunt in packs, because what they can achieve working together far exceeds the returns of more individualized efforts.

Patrols are conspicuous events that occur when multiple individuals, typically male, travel to the peripheries of their territory and sometimes deep into those of their neighbors. During these incursions, patrollers become hypervigilant and behave in other ways that suggest they are actively searching for neighbors. If the patrolling males find members of a rival group, they will attack and sometimes even kill them.

Unlike other animals, who will fight when groups happen to meet at the edges of their territories, male chimpanzees seem to deliberately search for neighbors while on patrols, potentially putting themselves in harm's way for uncertain gains.  Looking for trouble: Territorial aggressions and trespasses pay off among primates

That sounds eminently human but you're cautioned against anthropomorphizing; they're not human. Therefore, we watch to see whatever we can deduce from it.

So why do male chimpanzees choose to patrol when such forays may lead to violent, even lethal, encounters with members of neighboring groups? Patrols may benefit everyone by increasing the size of the territory and the food supply, but individuals also have the option to shirk patrol duty since unhelpful members are not punished or ostracized.

- PO

That screams of a metaphor relative to conscientious objection but we don't know why the so-called shirkers sit it out.  Maybe they're lazy or maybe they're gay or maybe they're gay and lazy ... we have no idea why they don't do it but we observe that's the behavior and continue.

Note:  of course some subset of gay men excels in the military and there are multiple movies but that's not the point; we don't know why some don't go out on patrols.

By combining analyses of patrol participation with results of paternity testing on 122 group offspring, Langergraber and colleagues found that, over the long run, patrolling paid off because it increased group size, which is important in determining success in competition against other groups.

"The Ngogo chimpanzees patrol and kill neighbors more frequently than any other chimpanzee group," says John Mitani of the University of Michigan, who has studied these particular primates for 22 years.

By 2009, the group expanded the size of their territory by 22 percent over the previous decade after killing 13 individuals from a neighboring group. Because of their success in competition against other groups, the Ngogo chimpanzees benefit from an unusually good food supply and long life expectancies.

- PO

Ed:  thanks for blasting pacifism into atoms to prove some scientific point!

Incorrecto, Mr Wizard, since you're anthropomorphizing and we're still observing which shows us the  group did well by this behavior.

But patrolling is a potentially dangerous as well as energy-sapping activity, and time spent patrolling is time that cannot be spent eating or mating with females in the safety of the territory. The study showed that males varied in how often they patrolled, and it was no surprise that high-ranking individuals, who were likely to be in good physical condition, participated frequently.

- PO

See, that's where America went wrong since it spends half its gold on patrolling and it's not the ones with the most to protect who do the patrolling but rather those who have the least and ...

Ed:  that's anthropomorphizing?


"We know that humans have means ranging from gossip to drastic punishment to aid cooperation in group settings," Langergraber says. "The puzzle has been to explain cooperation in animal societies, where shirking would seem an attractive option."

Most studies have focused on short term benefits of cooperation, he adds, "but our study shows the benefit of long-term data collection, and also that we still have a lot to learn from these chimpanzees."

- PO

Although I brought over quite a bit from the source article, the interested student will find additional links within that source to find more about this and ethology in general which has fascinated me since I was a kid and first heard of Konrad Lorenz with his geese.  (WIKI:  Konrad Lorenz)

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