Rare event of a chimpanzee gang murder of their alpha male

March 8, 2013 11:17 AM

"ET TU, chimp? The leader of a wild chimpanzee troupe was recently attacked by four of his underlings, who banded together to beat him to death. It's unusual for chimps to kill their alpha male – and this event gives rare insight into group structure in our closest relatives."
posted by Knigel (28 comments total)

Did it happen on the Ides of October ?

(I have no background about chimp group dynamics etc other than hearing Jane Goodall talk, and that was on the wrong species anyway..)
posted by k5.user at 11:31 AM on March 8

Not surprisingly, this is one of the top stories on reddit today.
posted by tapesonthefloor at 11:32 AM on March 8 [3 favorites]

"Wilson says male chimps compete for access to small numbers of females, so they have an incentive to kill each other."

This sounds like pretty old-school primatology to me. I mean, I realize that this is a story about a violent male-on-male chimp interaction, but it paints chimpanzees as generally violent and chimp sexuality as somehow controlled by male behavior in a way falsified long ago by Sarah Hrdy in The Woman that Never Evolved.

In fact, female chimps have sex with numerous males for each baby they produce, and by this they better the gene pool by mating outside the troupe, promote nurturant and peaceful behavior from males towards babies, and, by being "discreet," avoiding conflicts with other females. (Check out, for example, this article.)
posted by DrMew at 11:33 AM on March 8 [4 favorites]

The paper itself is behind a paywall, but the abstract is fascinating:

Chimpanzees (Pan troglodytes) are capable of extreme violence. They engage in inter-group, sometimes lethal, aggression that provides the winners with an opportunity to enlarge their territory, increase their food supply and, potentially, attract more mates. Lethal violence between adult males also occurs within groups but this is rare; to date, only four cases (three observed and one inferred) have been recorded despite decades of observation. In consequence, the reasons for within-group lethal violence in chimpanzees remain unclear. Such aggression may be rare due to the importance of coalitions between males during inter-group encounters; cooperation between males is also thought to be key in the defense or advancement of social rank within the group. Previous accounts of within-group lethal violence concern victims who were low-ranking males; here we provide the first account of the killing of an incumbent alpha male by a coalition of adult males from the same community. We found no clear evidence that the alpha male's position was under threat during the months before the lethal attack: the male dominance hierarchy was highly stable, with low rates of male–male aggression, and there were no significant changes in social interactions (i.e. grooming and aggression) between the alpha male and the other adult males. Two of the four attackers were former alpha males and were the individuals with whom the victim appeared, in the period preceding his death, to be most strongly affiliated: his most frequent grooming partners and those with whom he spent most time in proximity. The lethal attack triggered a period of instability in the male hierarchy and was likely an opportunistic attempt to seize alpha status by the third-ranking male.

posted by compartment at 11:35 AM on March 8 [2 favorites]

This sounds like pretty old-school primatology to me.

It's not a direct quote from the scientist, so it probably lost a lot of nuance in translation.
posted by Bookhouse at 11:38 AM on March 8

Thankfully, the hardcore right-wing doesn't believe in evolution or they'd be using this to squelch the revolution before it gets started.


I've said too much.
posted by Lemurrhea at 11:42 AM on March 8 [1 favorite]

Vinson: What you gonna do when you sittin' at the head of the table? Once you there, you gotta hold it down.

Marlo: Hmm...sound like one of them good problems...

Vinson: Prison and graveyard's full of boys who wore the crown.

Marlo: Point is they wore it. It's my turn to wear it now.
posted by (Arsenio) Hall and (Warren) Oates at 11:44 AM on March 8 [3 favorites]

redditor nastratin's post on the event which includes several other intriguing comments and links.
posted by Knigel at 11:49 AM on March 8 [2 favorites]

Interestingly, while physical intimidation is the clearest path to alphadom with most species, among chimpanzees it's possible to reach the top purely through social tactics, e.g. grooming. The topic of Chimpanzee politics is fascinating.

And for a more uplifting bit of primate news, here's a video of retired lab chimps going outdoors the first time in their lives.
posted by Doktor Zed at 11:49 AM on March 8 [3 favorites]

>ITT: Beta Stories

I'll start

>Be 9
>Watching troupe leader beat up second in command
>3 other betas hanging out near me
>Awkwardly mumble “s-sucks man”
>Spaghetti trickles down my fur
>We end up beating the alpha to death
>everythingwentbetterthanexpected.jpg
posted by ND¢ at 12:00 PM on March 8 [6 favorites]

Not surprisingly, this is one of the top stories on reddit today.

"How many comments before someone says ressentiment, I wonder?"
posted by Rustic Etruscan at 12:10 PM on March 8

I look at all primatology reports published in the popular press -- especially reports about group dynamics -- as inherently suspect until I hear them validated by someone who actually knows what they're talking about. In my experience they are usually more wrong than right, since the temptation to draw or hint at parallels between non-human-primate and human behavior is so strong that most journalists (and many scientists!) don't seem able to resist it even when those parallels are manifestly inappropriate.

I lack the expertise to be able to evaluate when such parallels are and are not appropriate based on the wretched table scraps of information handed out to the public in articles like this one (even the abstract of the sadly closed-access original article is more information-rich than the article in the FPP) so I prefer to just hold back until I hear from someone who does have that expertise.

I am sort of hoping that ChuraChura will come by soon and set us straight regarding what, if anything, is so interesting about this incident.
posted by Scientist at 12:21 PM on March 8 [3 favorites]

The typical end of a banana republic.
posted by Algebra at 12:39 PM on March 8 [5 favorites]

I immediately thought of totem and taboo, this is exactly what Freud talked about!
posted by jalitt at 12:44 PM on March 8

These chimps obviously heeded the wisdom of Omar. "Ayo, lesson here, Bey. You come at the king, you best not miss."

Also, anything written or spoken by Robert Sapolsky on chimps, all day. Google it.

Makes one realise our society's problems are about cortisol and social stratification.
posted by C.A.S. at 12:47 PM on March 8

I wonder if "He needed killin'" is considered a valid defense in Chimpdom...
posted by Greg_Ace at 12:51 PM on March 8 [1 favorite]

I'm a primatologist, but I'm not a chimp researcher. (I like my study subjects a little less terrifying.) I wasn't surprised when I read this in my primate news email alert. The media seem more excited about this than any primate researchers I know, since intra-group violence among male chimps is rare, but has been witnessed before. From the paper:

Nevertheless, within-community coalitional (or gang) attacks have been reported from both the wild and captivity [de Waal, 1986; Fawcett & Muhumuza, 2000; Goodall, 1992; Mjungu, 2010; Nishida, 1996; Nishida et al., 1995; Watts, 2004] although only four cases of lethal violence between adult males of the same community of wild chimpanzees have been documented despite decades of detailed observation [Sonso community: Fawcett & Muhumuza, 2000; Mahale M-group: Nishida, 1996, 2012; Ngogo community: Watts, 2004; Mitumba community: Mjungu, 2010; Wrangham et al., 2006]. Of these, one (in Mahale M-group) was inferred from circumstantial evidence while three were observed directly. In both the Sonso and Ngogo communities, the victim was a low-ranking young adult male, while in Mahale's M-group and in Gombe's Mitumba community, the victim was a deposed alpha male who was certainly (M-group) or probably (Mitumba) low ranking at the time of the attack. In addition, a gang attack on a deposed alpha male of Gombe's Kasakela community could have been fatal without human intervention [through antibiotic treatment: Goodall, 1992].

This is notable for being the first documented incumbent alpha male killing. Going along with what Scientist said above, this doesn't radically change or inform my views on human evolution. Chimps are chimps, and people are people. This just makes chimps all that more terrifying.
posted by bergeycm at 12:52 PM on March 8 [5 favorites]

This just furthers my dislike of chimps. Yes, even Lance Link.
posted by sonascope at 12:55 PM on March 8

OK. Here's my take on this. Though I don't study chimpanzees, I study competition and cooperation in another particularly aggressive species, Diana monkeys (though Diana monkey females are the aggressive ones!). My general reaction is that they observed some really cool behavior, reported it, gave reasonable theoretical discussions, and then further reporting sensationalized it and drew direct lines to human behavior.

Chimpanzee communities tend to be centered around maintaining strong ties between males. Female chimps leave the group they're born into at sexual maturity, leaving behind groups of males who have grown up together. Males tend to try to strengthen and maintain these social bonds, in part so that they have allies when coalitions form against them. Coalitionary aggression within and between chimpanzee groups is common. Lethal aggression between chimpanzee groups is relatively frequent, though I wouldn't say common. Lethal aggression within chimp groups happens more infrequently, but it happens enough that it has been observed several times. And lethal aggression that kills males of the same group, again, is infrequent but has been observed at least five times, including this article. However, this incident is the first report of lethal coalitionary intragroup aggression in which the victim was the dominant male.

The authors do some really cool contextualization of this event. Conveniently, there was an ongoing study looking at directional behaviors (things like who supplants whom, who grooms whom, who threatens whom, etc.) when they observed Pimu's death (and I should say, it looks like the actual fight leading to his death was videotaped by an ecotourism company; the context is from behavioral research being done by primatologists at Mahale, which has a long and interesting history of chimp research). Based on this research, Pimu (dead male) and Primus (male who was most directly involved in the aggressive interaction) had a highly antagonistic relationship. Proximity is a good measure of social tolerance: these guys were very rarely in close proximity and very rarely groomed. Pimu often directed aggression and Primus, and vice versa. When the fight occurred, Pimu and Primus were grooming eachother until Pimu bit Primus. After a serious fight, Primus called for other males to come and at this point in time the four males surrounded Pimu, biting and hitting him and preventing him from leaving. The authors suspect that he died from severe blood loss, based on an examination of his body after death.

OK, so all of that is pretty textbook behavioral observations. The authors then put this event into context in terms of primatological theory and other observations. This is not super surprising based on what's known of chimp behavior. Lethal coalitionary inter-group aggression is usually explained as part of a "war of attrition" between neighboring communities competing for the scarce resources of estrus females, and ripe fruit. Given that the males involved were the alpha male and another prime adult male (and they had a history of aggression), this could be attributed to something similar - especially if there are few estrus females in the group. It could also just be a byproduct of the general aggression that characterizes chimp communities. Either way, it's just an interesting thing. Like Bergeycm, it doesn't surprise me. It doesn't change my impression of chimp behavior, and I don't think it has particular implications for humans.
posted by ChuraChura at 12:58 PM on March 8 [11 favorites]

Remember, even though they are our closest genetic relatives, they are far away indeed, in terms of our closest /shared/ relative, oh those many Millions of Years Ago.

Chimps have gone one way, we have gone another.

However, they are highly socialized and socially contextualized creatures, just like us. So setting, context and environment matters. This is just as "natural" as genetics, which is only a part of this story.

So, yes, just like us they might conspire to neutralize a threat, even if that threat was an "alpha male". What is impeachment but stylized, politicized assassination?

Anyway, what if this behaviour is not a result of being a hominid of some sort, but is related to environment. One just has to cross a river in the Congo to find a much different sort of chimp culture (if you will) and then there are those pesky bonobos, so unlike either in this regard.

Also, until I read under what circumstances this behaviour was observed, we cannot discount human interference as a large factor. I know Goodall is a bit of a saint, but her methods were incredibly unsound and lazy ins many ways, and led to an understanding of chimp behaviour that is more about how chimps react to being fed by humans and the implications of scarcity.
posted by clvrmnky at 1:37 PM on March 8

Seconding Jalit. This is the primal horde in action!
posted by CCBC at 1:37 PM on March 8

Can I just say that all alpha males should be beaten to death by their underlings.
posted by the noob at 2:10 PM on March 8

> we cannot discount human interference as a large factor.

Any sign of a black monolith in the neighborhood that wasn't there recently?
posted by jfuller at 2:33 PM on March 8 [3 favorites]

I don't think that would count as human interference.
posted by Greg_Ace at 2:37 PM on March 8

Clvrmnky, you're overstating things. Jane Goodall's work was the first long term research done on any great ape. Yes, her initial methods can certainly be criticized, but provisioning ended in the mid 1970s and Gombe Stream is very, very restricted in the experimental research that can be done now in order to minimize the impact of research on chimp behavior as much as possible (to the degree that you can't even do playback experiments, which are pretty common for studying vocalizations). What substantive criticisms of her research do you have? One major issue at Gombe is that habitat loss around the park has restricted the chimps to a relatively small forest, and so population densities are increasing. That indeed might be causing increased aggression between groups and within groups. This study was at Mahale, which hasn't had provisioning in more than 20 years. Again, population density may be unnaturally high because of habitat loss, and that may have an impact, but chimpanzee aggression - even lethal, coalitionary aggression - is not rare, even in the most pristine of chimp habitats.

The comparison between chimps and bonobos are interesting. There are some important differences in their social structure, including the fact that males transfer out of the group they're born in at sexual maturity, while females stay in the same group and maintain close social bonds. They're also eating very different things, and living in very different habitats. Chimps are fruit specialists. Bonobos eat a lot of what's called terrestrial herbaceous vegetation, basically just foliage and plants and green things that are abundant and easy to access pretty much year round. Ripe fruit, on the other hand, is relatively scarce and distributed in patches that are too small to support an entire chimp community - and chimps will compete for access to ripe fruiting trees. One hypothesis for the difference in approaches to social interactions between chimps and bonobos is that, since bonobos are eating a pretty ubiquitous resource, they don't need to fight over it.
posted by ChuraChura at 7:39 PM on March 8 [2 favorites]

There's actually footage of the aftermath.
posted by Bunny Ultramod at 9:44 PM on March 8

Two of the four attackers were former alpha males and were the individuals with whom the victim appeared, in the period preceding his death, to be most strongly affiliated: his most frequent grooming partners and those with whom he spent most time in proximity. The lethal attack triggered a period of instability in the male hierarchy and was likely an opportunistic attempt to seize alpha status by the third-ranking male.

et tu, Brute?
posted by Golden Eternity at 11:42 AM on March 10

What Are Animals Thinking? Chimps, cats, parrots, dolphins, and dogs have surprisingly smart and emotionally rich minds.
posted by homunculus at 1:24 PM on March 12