Noisy chimps have more friends, hint at social origin of language

Researchers found chimps which use more noises to communicate have a larger social network, suggesting the origin of language might be to help us socialise.


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We are a very social species. It’s our greatest strength, allowing us to learn from and build on one another’s work. In fact, it’s thought our big brains evolved specifically to help us socialise. As any movie motivational speech will tell you, we work well together. And that reference to movie speeches isn’t completely a joke. It turns out the origin of language might be tied into our sociality as well.

This is because living in big groups isn’t all good news. Maintaining a group takes a lot of effort, which in turn takes a lot of time. In fact, calculations show that  if we bonded as “efficiently” as chimps we’d all starve to death since there would be no time left to eat, sleep, or reproduce. We needed to up our socialising game. And language is thought to have been the tool that allowed us to do just that.

Research on chimps is vindicating this hypothesis. Those who use more noises and gestures to bond can do so more efficiently. As such, they have a larger social group than their quieter counterparts. This provides evidence the origin of language might have its roots in bonding; and also suggests the chimps are one step closer to their inevitable rebellion.

An upper limit on friends

All of these issues stem from a simple observation. Primates with bigger brains live in bigger groups. In the 90s this led some researchers to speculate that there was a link between the two. Perhaps species evolved big brains to enable big groups. Living in large groups can be great since you have a lot of allies, but cognitively demanding, since you have to remember who all those allies are).

Subsequent research bore this out and it seemed like a solid (part of the) explanation for why some species have big brains. Including us. In fact, humans have taken it to such an extreme that we now have a brain 7 times larger than we should. Our group is proportionately massive too.  You may have heard of the famous “Dunbar’s number” (150 if you don’t have it memorised) which is the expected friendship circle we’re expected to have based on our brains.

The link between group size and brain size seen in primates (including humans), suggesting socialising and brains are linked

The link between group size and brain size seen in primates (including humans), suggesting socialising and brains are linked

Living in such large groups isn’t all good news. As I already mentioned, we need to maintain these social groups. Chimps primarily do this by grooming each other.  Unfortunately, this is a very inefficient system. With only one set of hands, you can only groom one person at a time.

As a group grows bigger the more time has to be invested in grooming. Estimates suggest that by around 1.5 million years ago groups would have gotten so big our ancestors would have had to have spent >20% of their day grooming to maintain them.

How much time we'd have to spend grooming if language didn't evolve. 20% is the cut off time for what is plausible

How much time we’d have to spend grooming if language didn’t evolve. 20% is the cut off time for what is plausible

Noisy chimps showing the origin of language

This is just impossible. No primate can spend that much time grooming and survive. They need to do other stuff than pick fleas off each other (as stereotypically monkey-ish as that is). This was thought to link into the origin of language. You can speak to a whole group, bonding with multiple people at once. The result is a much more efficient socialising system that could allow us to maintain our large groups.

Of course, we can’t go back 1.5 million years to see if our ancestors really starting giving each other cheesy motivational speeches around this time. There’s no FaceRock that preserves our ancestor’s social interactions. So whilst this explanation for the origin of language has remained popular, it’s only ever been tentative.

Though Australopithecus did collect a face rock, it preserves no information about who liked whom

Though Australopithecus did collect a face rock, it preserves no information about who liked whom

Some work on modern humans has lent further credence to it. It turns out we do mostly use language for socialising and it does allow us to do so more efficiently. But these are modern humans we’re talking about. We’ve been brought up to use language socially. So our non-linguistic ancestors might not have experienced these benefits.

Or at least, that was always the caveat. Work on chimps has found that they also get a social benefit from using noises and gestures. Not all chimps are born equal. Some have larger social networks than others. A review of the networks of a group of wild chimpanzees found that those with bigger networks used forms of communication other than grooming to sustain them. They would hoot, holler, gesture (and still groom) their chums.

Strength of the bond between individuals versus the interactions seen between them. Whilst grooming was still dominant, the closer chimps were the more they did other stuff

The strength of the bond between individuals versus the interactions seen between them. Whilst grooming was still dominant, the closer chimps were the more they did other stuff

Conclusion

This research is key because it shows you don’t need fully developed language in order to gain social benefits from it. Gestures and chimp-y noises are enough to increase the efficiency of socialising notably, compared to just grooming. This means our ancestors could have experienced similar benefits as they began developing larger groups. This could help explain why they were able to sustain such groups, and might be the start of the origin of language.

Of course, there are 14 million years of evolution separating us and chimps, so this isn’t conclusive evidence. But it is a vital step towards vindicating this hypothesis which has been kicking around for more than 20 years at this point. Further work in this direction could help provide key evidence that language really does have its roots in sociality (or finally disprove it, but based on this it seems unlikely at this point).

But perhaps the most notable conclusion is that chimps are getting in on the benefits of vocal communication. Clearly, this is another step towards their inevitable uprising against humanity. Next time you hear hoots, be afraid.

References

Aiello, L.C. and Dunbar, R.I., 1993. Neocortex size, group size, and the evolution of language. Current Anthropology, 34(2), pp.184-193.

Robin Dunbar (1998). The social brain hypothesis Evolutionary Anthropology

Roberts, S.G. and Roberts, A.I., 2016. Social Brain Hypothesis: Vocal and Gesture Networks of Wild Chimpanzees. Frontiers in psychology.

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