Humans are one of the most social primates. We're also one of the smartest (although bonobos seem to have a lot of stuff figured out). Could our sociality and smartness be linked? Certainly, Darwin thought so. He argued it was those social characteristics - in particular, our empathy - that gave us an evolutionary edge. And he's not the only one. Socialising has explained our big brains, language, technology, and much more.
Or at least, a lot of researchers think that socialising explains this sort of stuff. But many of these ideas have been challenged; if not outright disproven. Fortunately for Chucky D, research on orangutans suggests socialising might still explain our intelligence. Experiments on different species of the ape revealed that the more social an orangutan species is, the smarter they seem to have evolved to be.
Orangutans in a zoo
There are two species of orangutan: the Bornean orangutan and the Sumatran orangutan. Their names stem from where they live: Borneo and Sumatra. Because creative names aren't scientists' strong suit.
Besides the location, there are many similarities between the same species. Both critically endangered thanks to humans (go us). They both like to eat fruit, leaves, and other plant materials. Each species has a fairly complex vocal repertoire, which seems to be partly cultural in nature. All of these similarities are perhaps to be expected. Genetics indicates the species only split within the last million years. For context, humans and Neanderthals likely diverged around that long ago as well.
However, one key difference between the two species is their social life. They're both typically solitary animals, but Sumatran orangutans tend to bump into each other more often. They tend to congregate around bountiful fruit trees. When they do meet they're also more tolerant of, and willing to interact with, other orangutans.
Many researchers think socialising can be a big factor in evolution. It provides a lot of opportunities, but also many costs. So natural selection might drive the development of features to mitigate some of those costs, and encourage more socialising. Intelligence, in particular, might be intertwined with socialising.
If that's really true, then the Sumatran orangutan should be smarter than their more asocial counterparts. And scientists did determine they were after examining apes from 9 zoos across Europe. Sumatran orangutans displayed better problem-solving skills and greater inhibition than there Bornean chums.
Socialising helped me and you
Science is all about coming up with an idea. You then make predictions about how the world should work if that idea was true. Vindicating those predictions counts as points in favour of that idea. And this does certainly seem to be a case here. Two similar species, separated by only a blink of evolutionary time, still evolved cognitive differences. Those differences seem to correlate with sociality, which was the prediction all along.
Of course, the idea that socialising (partly) drives intelligence isn't new. It was most notably put forward in the " social brain hypothesis ". As the name suggests, that hypothesis claims a link between socialising and intelligence. Again, creative names aren't where scientists shine. Yet they're definitely informative.
The social brain hypothesis has a fair bit of evidence for it. It was initially based on a rather strong correlation between brain size and group size in primate species. Further research has shown that more social individuals tend to have more babies (that survive). This would seem to confirm that socialising does offer some key benefits.
However, the idea has also had many critics; myself included. For example, it also predicts that people should live in groups of ~150. Other research suggests the actual number may be closer to 1,000. Additionally, archaeological evidence suggests our ancestors lived in groups smaller than expected.
Can orangutans be trusted?
This ongoing debate means the extra evidence is extra important in clarifying things. At this point, it looks like the social brain hypothesis has taken too much of a beating to explain our smarts in its entirety. However, the fact aspects of it keep being vindicated - like with these orangutans - suggests socialising did play a role in the evolution of our intelligence. But it likely isn't the sole cause, hence why so many aspects don't quite line up.
Of course, this is all assuming that this additional evidence can be trusted. Is experimenting on orangutans a reliable way to study the evolution of the brain? It's not a foregone conclusion. Only a handful of each species was investigated, and they all lived in zoos. Such environments have been shown to influence the thinking of apes living there.
That's not to say this research is wrong. Just that it won't be the last word on the subject. Not like that should stop you socialising. Don't become aloof until the evolutionary benefits of bonding have been proven. We know it's a big deal. The question is just how big that deal is.
Conclusion
Experiments on different orangutan species has revealed that the more socialising a species does the smarter they've evolved. Could there be a link? It seems likely, but more work is needed.
References
Dunbar, R. I. (2003). The social brain: mind, language, and society in evolutionary perspective. Annual Review of Anthropology, 163-181.
Collard, M., Buchanan, B. and O'Brien, M.J., 2013. Population size as an explanation for patterns in the Paleolithic archaeological record. Current Anthropology, 54(S8), pp.S388-S396.
Forss, S.I., Willems, E., Call, J. and van Schaik, C.P., 2016. Cognitive differences between orang-utan species: a test of the cultural intelligence hypothesis. Scientific Reports, 6.
Vaesen, K., Collard, M., Cosgrove, R. and Roebroeks, W., 2016. Population size does not explain past changes in cultural complexity. Proceedings of the National Academy of Sciences, 113(16), pp.E2241-E2247.
