Meet ethoarcheology, the fascinating study of animal culture over time
Just look at this monkey and tell me that’s not awesome. Yes, it’s only a monkey hitting rocks against each other. But the amazing thing is: it’s a monkey hitting rocks against each other! What I’m trying to do with the rest of this post is to give a bit of context to help you see why this is awesome if you don’t see why it is, so keep reading if you’re interested.
Ethoarcheology is a relatively recent development, so recent that google insists on wanting to correct it to ethnoarcheology. As many of you may know, it is no longer taboo to talk about animal culture. We know that some behaviors in non-human species are culturally transmitted and different different even within species, instead specific to communities of individuals. For example, whales have regional dialects, as do birds, and the hunting strategies of killer whales is different from group to group.
Well, scientists studying the spatial patterning of chimpanzee artifacts and behavior stumbled upon a legit archaeological sites in Ivory Coast. The kicker being, the stone tools they found in this sites weren’t of human origin : they were the remains of a 4000 year old chimpanzee culture. It quickly became evident that chimpanzee created long-lasting patterns of material cultures, not only with stone tools, but also with nests and plant tools. In fact, there has been some worries that early archaeology might have falsely attributed sites to early hominin when they were in fact from our cousins.
Which brings us to another country, Brazil, and another species, the bearded monkey or Sapajus libidinosus. In the video we see them smash rocks against each others, but usually they also use these rocks as hammers and anvils to open cashew nuts. They found a 3 millennia long archaeological site, that breaded monkeys had used to open nuts all this time. This is the first long-term record of tool use in a non-human species.
Interestingly, there is a bit a variation going on. The researchers identify 4 different phases of tool use, depending on the size of the hammers and anvil, what they are made of (sometimes, the anvil is a piece of wood instead of another stone), and the patterns of damages, an indication of how they were used. For example, from around 200 years ago to 30 years ago, they used larger and heavier rocks than either before or after, an evidence that they were using it to open harder food than the cashew to eat now. Did the food source change or their taste ? No one knows, but in either case this means they are able to change which tool they use if they need or want to open different things.
Back to the beginning video. The real kicker is, this is the first evidence of a non-primate species producing large amount of stone flakes. This may seem innocuous, but archaeologist rely heavily on the shape of these flakes to infer early hominin development, from Australopithecus to modern humans, so much so that it sometimes helps classifying remains as either habilis or erectus. And now not only is it not reserved to humans, it’s not even reserved to apes.
Apart from to kick to our ego, the most interesting part to me is that they lick the flakes for some reason. It may very well be for the same unknown reason (ingesting silica, lichen or whatever ?) that our own ancestors started mashing rocks at each other. And only later realized that they could do stuff with the pointy by-products of their smashing, in probably the most important accidental discovery of the history of human history.
On a final sobering note, some authors note that this may be yet again a way in which we screw up these species. By partitioning their habitat to colonize the forests, we fracture these communities and may be preventing cultural transmission when some of it helps animals access food and avoid predators.
Some academic sources if anyone is interested :
Primate archaeology evolves, a review paper from the founders of this discipline.
Three thousand years of wild capuchin stone tool use, the fascinating study of the millennia-old nut smashing site.
Chimpanzee nest distribution and site reuse in a dry habitat: implications for early hominin ranging. Or how we might be mistaken about early hominin range because we confuse chimpanzee traces with human ones (Sorry this one is the elsevier link, you’ll have to smash the paywall yourself with your method of choice.)
Hope this write-up interests some of you.
Posted Mar 12, 2020, 12:41 PM UTC