Tensions Mount between Frodo and Patrick

In recent weeks the aggressive encounters between Frodo and Patrick have become more frequent. One reason for this is the presence of Lome. Lome is a sub-adult male, now approaching his tenth birthday. He isn't yet fully-grown, and his calm demeanour means that he rarely behaves aggressively towards others. Nonetheless, he's becoming large enough that he can contribute a useful amount of muscle to any conflict into which he's drawn - at least to fend off adult females, if not any of the adult males. Unfortunately for Frodo, Lome is also Patrick's brother.

While all of the younger chimps in the group (aside from Swela) were sired by Robert - making all of the males half-brothers - Patrick, Lome and Lobo all share Corrie as a mother. Although the effects of this aren't always obvious, it means that they have closer bonds than the other males; and these have been enhanced by a history of grooming and playing together. Now that Lome is coming of age, his closeness to Patrick is becoming a threat to Frodo on account of the natural allegiance that they share.

The emergence of Lome has left Frodo isolated and vulnerable. About a month ago, Patrick tore a chunk out of his foot, leaving him unable to defend himself properly. As a consequence, Frodo was forced, for the first time, to back down from a number fights with Patrick. If this situation persists, he will lose his dominant position in the group, and the access to women that this dominance brings.

In order to shore up his own position Frodo has started looking for new allies. This is why he and Robert have been grooming so intently: by recruiting the retired alpha as a support, perhaps in return for some limited access to females, Frodo can protect himself from the challenge presented by Patrick and Lome. This is also why, in the previous post, Frodo was so infuriated by Patrick's breaking up his bonding session with Robert: it's only by cultivating that relationship that Frodo's position in the group will be secure.

This is particularly true since Patrick also enjoys the support of the majority of the females in the group, who still remember the beatings Frodo dished out to them two years ago when he was trying to assert his own authority of the then-dominant Robert.

Jealousy in Adult Males

Three adult males dominate the A group of chimps. Frodo is the current alpha, having deposed his father, the aging Robert, a year or so ago. Frodo is stocky but calm and a little solitary. He spends much of his time sitting alone, arms crossed and with his head resting on his knees, staring into space with an expression that is part pensive and part grouchy. When he plays, it is most often with Kofi. Robert, who is dark-skinned and has an elegant drooping mouth, is now retired; his place in the group assured by age (and sometimes, I think, a touch of senility). He spends a lot of time grooming, and although his pant-hoots are often the first sign of tensions building within the group, he no longer challenges others. The challenger is Patrick, who is younger and more slender than Frodo but more ambitious. He spends his days asserting himself against Frodo and some of the more senior females (especially Riet), and playing with his younger brothers Lome and Lobo.

Yesterday afternoon at about 4pm, we arrived at the observation tower to find Robert and Frodo sitting below us, engaged in a very tender moment of male-bonding. They faced one another, open-mouthed and shook their hands and heads at one another excitedly, while grunting and occasionally gripping each other's wrists playfully. Their hand movements were gesture-like, but didn't appear to have any purpose; so while their interaction rather resembled a conversation - or maybe a game of stone-paper-scissors - I don't think that it was. (Since it also lacked a clear turn-taking structure, I don't think it was proto-conversational either.) They were just playing, but in a very absorbed manner - and on several occasions when Dorien came over to try to join in their fun, they moved away from her, so as not to be interrupted.

This was the first time I'd seen adult chimpanzees engage in this fascinating sort of interaction before. But what was going on in the background made it even more remarkable. 

Patrick had been watching Frodo and Robert with a sense of growing frustration, and after several minutes of being shut out of their game he could no longer control his rage. Standing upright and hair erect on a step about a metre behind them, he swayed from one foot to another and rocked his shoulders in a classic threat display. Then, when he could no longer control his frustrations, he ran past them, charging the air about a metre to the left of their huddle. Patrick was jealous of the bond forming between his rivals.

When Frodo and Robert ignored his first charge, Patrick charged again, striking out not only at the males, but also at the group of older women that had surrounded them. All hell broke loose, and to the screams of 15 agitated onlookers, Frodo chased Patrick to the top of one of the higher trees in the enclosure. There Patrick was met by a group of females who shielded him, while a furious Frodo swung violently on a rope several metres below, waiting for him to come down.

Several minutes later, with calm restored, Robert, Patrick and Frodo returned to the corner of the enclosure where Robert and Frodo had been grooming. Only now it was Patrick who went to sit next to Robert, and Frodo's turn to be angry. Patrick had set out to disrupt the bonding taking place between the two others, and had succeeded.

When he saw that Patrick had taken his place, Frodo paced the edge of the grooming-corner angrily. He then charged a wall and kicked it, before picking up a torn-off tree branch and swiping and hurling at no one in particular. A moment later Lobo, Patrick's younger brother, picked up the thrown stick and struck out at Frodo with it - suggesting that not only had Frodo's game been ended, but also that his authority had been undermined by his losing encounter. (Typically the younger males would not dare challenge a charged-up alpha; it would be a recipe for hurt.)

Ten minutes later, in an act of reconciliation, Patrick approached Frodo to groom him. For now at least the hierarchy was restored, and with it calm returned to the group. It will be interesting to watch this rivalry develop, though.

Third Party Punishment in Chimpanzees?

Today just after 6pm Swela, a relatively low-rank and highly-strung young adult female - and also my favourite female in the group, on account of her sad eyes and warm demeanour - started to scream. Riet, the giant and dominant female of the group, had stolen her blanket. Swela often carries a blanket, which she clutches to her chest as one would a child; but Riet also likes to sleep on the sack-cloth out of which they are made. When Swela screamed she ran towards other chimps and pushed her face close to theirs, baring her teeth, so as to present to them her distressed expression. Then she alternated her gaze back to Riet and then to her interlocutor. It was if she was saying "See what she's done to me! Look at my pain!".

(One advantage of posting these thoughts here is that when I'm being a proper scientist at work, I can't anthropomorphise the chimps to extent that I might here.)

One of the chimps whose attention was caught by Swela's screams was Kofi, a juvenile male. Kofi is beautiful, hilarious and, along with Swela, unquestionably my favourite of the A chimps. He has no fear and our keepers worry that he will grow up to terrorise the group, because despite being only 6, he spends his days throwing beetroots at the heads of the highest-ranking chimps - including Frodo, the alpha male and Kofi's best friend - and whipping them with sticks. (If he were a human child, we'd find it natural to describe his behaviour as 'testing the boundaries'. I don't know if that's really an appropriate way to describe Kofi's behaviour, because chimps may lack the understanding of behavioural norms that this would seem to imply.) When Kofi heard the screams, he looked at Swela, and followed her gaze to Riet, who was holding Swela's blanket. He then ran to Riet and started whipping her with the long stick he was holding.

Why is this interesting? Well, one possibility is that it's evidence of third party punishment in chimpanzees. Third party punishment lies at the origin of our legal system. Where someone violates a group norm in human societies, typically they are not themselves required to inflict justice on their aggressor. Rather, the state intervenes and does it for them. Third party punishment is foundational for human society because it centralises the balance of power, enabling the enforcement of norms where individuals might be powerless to act. It's therefore a very powerful mechanism for the enforcement of group norms, and the regulation of antisocial behaviour.

So was Kofi's behaviour an instance of third party punishment? Well, as with many cases of observation, it's very difficult to tell. A major worry here would be that Kofi is for the most part only too happy to whip his higher-ranking peers with sticks. In that case, this encounter could just be a coincidence, and point to nothing more profound than Kofi's violent tendencies. This reading of the scene would be reinforced by the fact that when my colleagues have run controlled studies designed to test for the presence of third party punishment in chimpanzee communities, they found no evidence (Riedl, Jensen, Call, & Tomasello: (submitted) No third-party punishment in chimpanzees). In other words: there was no significant difference in the tendency of chimps to punish between the test condition and the control conditions introduced to rule out alternative explanations.

It's not impossible that Riedl et al. failed to uncover a real phenomenon of chimpanzee behaviour. Nonetheless, given the combination of experimental findings and Kofi's whip-happy behaviour, it would surely be premature to conclude that he was engaging in third-party punishment - even if it is tempting.