Humans eat more meat than any other living primate. This might just seem like a fun little fact, but it could actually be the secret to our success. Some scientists think eating meat provided the fuel for our big brains.
So to understand why humans took over the world, we need to figure out when meat took over our lives. Figuring out when this happened is a bit tricky as it turns out our ancestors didn’t really keep cookery books.
Fortunately, they did do something that left a trace: they chopped up their food with stone tools. This leaves tell-tale marks on both the fossils and the tools. By studying them, scientists have discovered that eating meat might be very old indeed.
The first meat eaters
Our lineage split off from the other apes around 7 million years ago. Despite that, our lineage wasn’t recognisably human for most of that time. We would have looked like just another African ape (albeit an upright one). The famous Lucy fossil represents this period well.
Even though these early humans were very different to us, they may have been the first meat eaters. The earliest evidence of cutmarks on bone comes from 3.3 million years ago. That’s only a hundred thousand years older than Lucy. In fact, the cut fossils were found <5km from her1!
This nearby site is called Dikika. There, scientists found several fossils on the surface with what appeared to be cutmarks. By looking at the sediment trapped on the fossils, they figured the bones came from a rock layer formed 3.39 – 3.24 million years ago. Also known as Lucy’s age1.
However, this didn’t convince everyone. Surface finds cause issues as identifying the layer they came from is hard, particularly with the sediments at this site. It also means that they may have been damaged whilst on the surface. Experiments show that animals running over the bones could cause similar marks2.
Or it could be crocodiles. Researchers examined bones of their prey and found that crocodile teeth make a distinct V-shaped mark. This is surprisingly similar to the sort of damage produced by tools, but it is possible to tell the difference if you know what you’re looking for. So, knowing this, scientists re-examined early evidence of cut marks, including Dikika.
The results clearly showed that it wasn’t our ancestors eating meat 3 million years ago. It was crocodiles.
The real first meat eaters
Once you rule out possible crocodile bones there’s little evidence of meat eating during Lucy’s time. Only 13 other damaged bones from >2 million years ago have been found. Some fall in the small overlap between tool damage and crocodile damage, but that’s hardly compelling evidence3.
Instead, we have to look after 2 million years ago for solid evidence of the first humans eating meat3. This is important because it coincides with the evolution of Homo erectus. They were the first of our ancestors you’d probably recognise as “human.” Although they did have smaller brains and flatter foreheads, what does that matter between family?
Several sites are known from this period with loads of cut marks that clearly aren’t crocodiles, including Olduvai Gorge and Koobi Fora4. Given the age of these sites, we can say with confidence humans started eating meat between 1.7 – 2 million years ago4.
Of course, that doesn’t mean that these fossils are without controversy. Debate remains over whether Homo erectus was actively hunting these animals, or just scavenging the kills of other predators4. However, by around 1.8 million years ago they were hunting at least parttime. Olduvai Gorge contains butchered prime-adults prey (which other predators tend to avoid).
So not only was Homo erectus hunting, it was good at it.
Humans reliant on eating meat
Saying that humans started eating meat 1.7 – 2 million years ago is a bit of a lie. Chimps will hunt and eat meat today, sometimes with spears. They just don’t do it very often. Given we’re closely related to chimps, our early ancestors may also have been occasional hunters for millions of years. Maybe also with wooden spears.
What we really want to know is when did humans start eating a lot of meat. When did we shift onto the modern-style diet, where meat can make up half of hunter-gatherers diet5.
Like pinpointing the origin of meat eating, this is hard to figure out. We can’t simply count up butchered fossils at a site to see how much meat Homo erectus ate. For all we know, that site could have formed over hundreds of years and represent a little bit of meat for each person, or formed quickly and represent a meat feast. That long ago we just don’t have the resolution to figure it out.
However, there is some circumstantial evidence Homo erectus was reliant on meat not long after they started hunting. There is a child that died 1.5 million years ago from vitamin b-12 deficiency. Most of us get our b-12 from, you guessed it, meat. Clearly, for this person was so reliant on meat that not having it killed them.
Of course, that youngster might have just been a weird meat-freak. And Lucy could have hunted without us knowing. There’s a lot we still don’t know about when humans started eating meat. Just that it was a big deal when it happened.
- McPherron, S.P., Alemseged, Z., Marean, C.W., Wynn, J.G., Reed, D., Geraads, D., Bobe, R. and Béarat, H.A., 2010. Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia. Nature, 466(7308), p.857.
- Domínguez-Rodrigo, M., Pickering, T.R. and Bunn, H.T., 2010. Configurational approach to identifying the earliest hominin butchers. Proceedings of the National Academy of Sciences, 107(49), pp.20929-20934.
- Sahle, Y., El Zaatari, S. and White, T.D., 2017. Hominid butchers and biting crocodiles in the African Plio–Pleistocene. Proceedings of the National Academy of Sciences, 114(50), pp.13164-13169.
- Domínguez‐Rodrigo, M. and Pickering, T.R., 2003. Early hominid hunting and scavenging: a zooarcheological review. Evolutionary Anthropology: Issues, News, and Reviews, 12(6), pp.275-282.
- Crittenden, A.N. and Schnorr, S.L., 2017. Current views on hunter‐gatherer nutrition and the evolution of the human diet. American journal of physical anthropology, 162(S63), pp.84-109.