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First lethal attacks by chimpanzees on gorillas observed

113 points10 hoursmpg.de
varenc8 hours ago

> "Whether this behavior is due to competition for food or to the decline of the rainforest's productivity caused by climate change will now be investigated in more detail."

Declaring the cause must be food competition or climate change seems a bit hasty?

These are complex social animals. Given this is the only attack ever observed, it seems possible to me that there are a myriad of plausible one-off explanations. Perhaps a particular chimp or gorilla was having a really bad day and just went out looking for a fight.

subroutine8 hours ago

Indeed. Chimps will eat gorilla infants. So if the attack was over a scarcity of food resources you'd expect the killed infant to be eaten. This was only observed in 1/2 the encounters...

> Between 2014 and 2018, we observed nine direct interactions between individuals of the Rekambo community and unhabituated gorillas (N=9; see Fig. 1). These events were always peaceful, and occasionally involved co-feeding in fruiting trees (N=2). In 2019 however, we observed two encounters resulting, in both cases, in coalitionary lethal attacks. The first encounter involved a party of 27 chimpanzees and a group of five gorillas. The second involved a party of 27 chimpanzees and a group of seven gorillas (see Table 1, and video clips 1 and 2 in the SA). The first event occurred after a territorial patrol during which the males made a deep incur- sion into a neighbouring chimpanzee territory. The second event happened at the start of a suspected territorial boundary patrol. Both events took place on the outer boundaries of the Rekambo territory (see Fig. 1). The main aggressors in both events were adult male chimpanzees (for details of involvement see Table 1). The two encounters lasted 52 and 79 min, respectively, involved both contact and non-contact aggressions and coalitionary displays from chimpanzees towards gorillas. The gorillas counter attacked and defended themselves using contact aggressions, displays and threat gestures. During the first encounter the silverback was present for 14 min, whilst in the second encounter the silverback was present for 10 min. The first encounter resulted in one dead gorilla infant and three injured chimpanzees; the second resulted in one dead gorilla infant. While there was no indication of consumption of the dead gorilla infant in the first encounter, the infant in the second encounter was almost entirely consumed by one adult chimpanzee female.

https://www.nature.com/articles/s41598-021-93829-x.pdf

kadoban6 hours ago

The non-eating attack resulted in chimpanzee injuries. They very well could have been chased away and/or too busy nursing injuries.

gchamonlive8 hours ago

They are not declaring that. The proposed cause is a thesis that will be investigated further and could very well be disproven. I don't see what's wrong with that.

krona1 hour ago

I'm not sure how the thesis could possibly be disproven. Interviews with the apes?

smhost8 hours ago

> Perhaps a particular chimp or gorilla was having a really bad day and just went out looking for a fight.

This doesn't necessarily contradict the food competition or climate change hypothesis. To the individual ape it might seem that he's just having a bad day, but then you could look at weather/food data and compare it to incidence of violence and see a causal relation. It would actually be surprising if those things didn't affect ape behavior.

hutzlibu2 hours ago

I know many humans who get very grumpy on an empty stomach.

parineum8 hours ago

That phrasing struck me as well. It's a classic false-dichotomy. It's funny to me to see it so prominent in what appears to be a fairly professional site.

diognesofsinope8 hours ago

They've turned climate change into the new boogeyman, which is a shame since it's an important issue.

denkmoon4 hours ago

and why is it an important issue? In part because of the ecological stresses it causes, which results in less supply of resources in a given ecological niche.

Seems entirely reasonable to hypothesise the cause of aggression being related to this. That's not something they tested, merely a proposed hypothesis.

robbedpeter2 hours ago

It's a convenient hypothesis, given the ubiquity of climate change impacts, but also a lazy one, like blaming the aggression on something equally as prevalent and relevant to the situation, like chimp genetics. The hypothesis is untestable absent some other specific assertions, and therefore unscientific.

skocznymroczny2 hours ago

Give it few more weeks of research and they'll blame it on covid.

raffraffraff3 hours ago

Makes your wonder why Neanderthals only survived as fragments in our DNA.

jansan5 hours ago

If you want public funding in Germany, you better make sure that you cover either diversity or climate change with your research. Not sure how they missed the opportunity to give "lack of group diversity" as a possible reason for the attack.

meristohm6 hours ago

Does writing off climate change as a factor seem a bit hasty?

Even if it’s just a one-off, terrible-horrible-no-good-very-bad-day event, one effect of changes in average local weather might be that many individuals are more stressed.

isolli1 hour ago

I remember once watching a documentary on a roving band of chimpanzees, and thinking how human they looked. I was shocked when they attacked another band of chimpanzees and killed them all. However, I quickly overcame my shock. They were quite human indeed...

Someone2 hours ago

From the videos, it looks like the human observers were about ten meters away.

That made me wonder how risky filming this is.

Google didn’t give me cases of attacks on observers, but it did give me https://observers.france24.com/en/20120926-midst-armed-confl..., so I think those observers are at some risk.

It also taught me chimpanzee wars exist (https://www.newscientist.com/article/mg22229682-600-only-kno...)

austhrow7439 hours ago

Never have I been more disappointed that an article didn’t include video.

subroutine8 hours ago
isoprophlex1 hour ago

"At 13:15, Chenge followed by an adult female, Roxy, climbed up the tree. Roxy moved toward Greta and took the body. She then began to consume the hands and internal organs of the gorilla infant. Between 13:16 and 14:00, Roxy allowed Chenge, Littlegrey, Onome, Orian, and Queliba to access small amounts of meat, no begging behaviour was observed between individuals. A final gorilla chest beat was heard at 13:46 in a North-East direction of the observers."

That's pretty gruesome.

blueblisters7 hours ago

That looks like a scene from a Stanley Kubrick movie :)

fiestaman4 hours ago

Direct link?

dhosek8 hours ago

As a child, I would hear news reports talking about guerrilla attacks. It wasn't until I saw a Mad Magazine feature with a title along the lines of "if only the news meant what it sounded like" with a picture of gorillas attacking a city that I realized that they not gorilla attacks (I think it was a while longer still before I knew the word was guerrilla—I was a kid, OK?). This is the first sign that maybe the world could be as interesting as I imagined.

warglebargle6 hours ago

cool

soheil8 hours ago

For videos scroll to the bottom of this page https://www.nature.com/articles/s41598-021-93829-x

vmception9 hours ago

Gorilla infants were killed while the adults escaped

Although noteworthy that the chimpanzees scattered and broke down the defenses of Silverbacks, it would be more noteworthy if they took down an adult male

CryptoPunk8 hours ago

I am surprised silverback gorillas were not capable of protecting their clan.. A full grown gorilla has a 1,300 PSI bite force.

woko2 hours ago

There were 18 chimpanzees vs. 1 silverback. While the silverback was getting harassed by 10 chimpanzees, the gorilla infant could be targetted by the other chimpanzees.

Moreover, the silverback was troubled by the presence of human observers and fled 3 minutes later, whereas the chimpanzees were habituated to the human presence.

Quotes below:

> In both events, the chimpanzees considerably outnumbered the gorillas. [...] At 17:13, the silverback charged an adolescent female chimpanzee, Gia, knocking her into the air. At 17:15, a group of approximately nine male chimpanzees (adults and adolescents), and at least one adult female chimpanzee surrounded the silverback, and repeatedly jumped down on and hit him whilst screaming and barking. [Meanwhile, the gorilla infant could be kidnapped by the other chimpanzees.] At 17:22, one adult male chimpanzee, Littlegrey, was observed sitting on the ground holding a gorilla infant in front of him.

> During the first encounter the silverback was present for 14 min [out of a total of 52 min], whilst in the second encounter the silverback was present for 10 min [out of a total of 74 min]. [...] At 12:33, the silverback discovered the human observers on the ground in a distance of approximately 30 m to the base of the tree and started barking. [...] At 12:36, the silverback rapidly climbed down the tree and fled. The chimpanzees continued barking but did not follow him. [...] We cannot rule out that the presence of human observers, in both events, may have had an effect on the unhabituated silverback’s departure and may have tilted the imbalance of power in favour of the habituated chimpanzees.

pingou1 hour ago

If I was one of the researchers, I would be very worried about having been associated with this encounter, the next time I see some gorilla.

kadoban6 hours ago

On the face of it that does seem surprising. With (vastly) superior numbers and a focus on confusion and harassment though, I can easily imagine a gorilla being unable to fend them off completely.

AwaAwa8 hours ago

How us Chimps captured King Kong is beginning to make more sense.

nvader9 hours ago

Apes apart weak.

HeyZuess9 hours ago

I for one welcome our new chimpanzee overlords.

HeyZuess9 hours ago

I think the gorillas are now angry and down voting.

mullikine8 hours ago

This is how it happened.

At each step of the evolutionary ladder, there is a confrontation from one species to the next; A battle of hairy to slightly less hairy homonids. Two meet on a grassy plain, their stares communicating that this is the final straw. You came into our banana plantation the last time. A thought reverberating through the millenia. Once again, two creatures play out their parts, employing different gifts bestowed upon them by nature, now to challenge eachother in mortal combat. One with a slightly more developed brain, and the other with slightly more developed muscles.

Partially written with GPT-3.

https://asciinema.org/a/oQBzOj1Q3CTDxc2rwu2hLBT6R

oh_sigh8 hours ago

Meta: Any HN threads where 90% of the comments are "jokes" should just be deleted.

dmos624 hours ago

Depends if the jokes are good.

TroisM8 hours ago

no... thanks for trying to censor everything though... you sound like Mods on a bad day.

oh_sigh8 hours ago

Deleting a thread on a tech forum with no substantive discussion about great ape behavior is not "censorship" or "censoring everything"

Retric8 hours ago

HN is not strictly a tech form. The goal is what’s interesting, the audience is tech focused but the third ranked link is currently:

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Yesterday’s top 10 had: https://news.ycombinator.com/front?day=2021-07-20

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+1
j_koreth8 hours ago
h0l0cube6 hours ago

To be fair, substantive discussion has emerged and all the tomfoolery has been downvoted. Steady as she goes

hungryforcodes5 hours ago

It most certainly is censorship done arbitrarily-- the voting system is there to reflect the attitudes and desires of the users.

But let's go further and just delete articles on gorillas and the dangers of mindfulness meditation as well? They have nothing to do with tech, anyways...

d110af5ccf8 hours ago

> is not "censorship" or "censoring everything"

Actually, that would in fact be a very straightforward example of censorship. Which isn't to say that it would necessarily be a bad thing - moderation involves limited and targeted censorship.

Let's not go redefining words in order to defend a particular course of action. We should argue the actual merits instead.

jakeinspace8 hours ago

Agreed. Fun should not be tolerated. This is a serious place for serious discussions and dour faces. I'm frowning as I pound this out on my keyboard.

soheil8 hours ago

> The increased food competition may also be caused by the more recent phenomenon of climate change

Way to go, jumping right into speculation, as scientists they shouldn't be so trigger happy, specially given that they go on to say

> We are only at the beginning to understand the effects of competition on interactions between the two great ape species

CamperBob29 hours ago

About time. As a civilization, we desperately need a monolith or two to show up right about now.

dboreham9 hours ago

Just split the monolith into several smaller repos.

SV_BubbleTime9 hours ago

IDK, someone is just going to argue it should be packed back into a monolith over and over. Despite there clearly being no right answer.

dukeofdoom9 hours ago

Joe Rogan needs to know about this as soon as possible. The guy loves talking about chimps on his show.

yosito3 hours ago

A hundred percent

ampdepolymerase9 hours ago

Time for Manning's to release a Natural Selection in Action series.

zzt1238 hours ago

A modern day analog of the conquest of Neanderthalia by the strange, physically weaker cousins from down under.

pope_meat9 hours ago

Historians will be completely befuddled trying to understand how THIS was the instigating factor for the series of events that lead to WW3.

labster8 hours ago

> In the encounters, which lasted 52 and 79 minutes, the chimpanzees formed coalitions and attacked the gorillas.

Gorillas needs to watch their aggressive expansion. Especially since Chimpanzee tribes are overpowered since Leviathan.