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Let’s talk about the biggest coincidence in human evolution. To fully appreciate this coincidence, you need to see it in context. The oldest known hominins lived 7 million years ago, so we have been evolving separately from apes for at least that long. Our own species, Homo sapiens, seems to be about 300,000 years old.
For functionally all of that time, hominins (including our species) were hunter-gatherers. Then, starting around 10,000 years ago, some groups started farming.
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So far, so story of supposed progress. But here’s the key point: multiple groups invented farming completely independently of each other, on multiple continents, within a few millennia. That includes people living in the Americas, who had been cut off from populations in Eurasia and Africa for thousands of years – yet they took up farming so soon after people in Eurasia that the difference is basically a rounding error. Likewise, people in New Guinea started farming at the same time as people in Eurasia.
It would be one thing if farming had been invented once, in one region, and then spread rapidly. But that is, unambiguously, not what happened. Separate groups, with radically different cultures, living in different environments, and with no means of communicating with each other, all started farming at basically the same time.
If that isn’t a coincidence worthy of explanation, I don’t know what is.
From Mesoamerica to New Guinea
Quite how many societies have independently invented agriculture is interestingly vague. In a 2015 feature for żěè¶ĚĘÓƵ, Bob Holmes put it at 11, on four continents (Eurasia, Africa, North and South America). However, a 2023 piece in the journal PNAS suggested there were “” distinct origins. Without trying to be definitive, it’s safe to say that more than 10 societies independently came up with farming, all within a few thousand years.
When lots of groups independently do the same thing, it’s tempting to look for a common factor.
We might invoke human uniqueness, some capability that our species has that other hominins like Neanderthals didn’t. But that raises two questions. First, what ability are we talking about? And second, presumably we had that ability throughout our existence, or at least for most of it – why did so many separate populations simultaneously do the same thing, after hundreds of thousands of years?
So instead, maybe there was some external factor that all these societies were experiencing.
One obvious possibility is climate change. Between about 115,000 and 11,700 years ago, Earth was in a glacial period: the average global temperature was cooler and ice sheets advanced from the poles towards the equator. The coldest point, the last glacial maximum, was between 26,000 and 20,000 years ago. After that, the planet gradually warmed up. Since about 11,700 years ago we have been in an “interglacial”, called the Holocene epoch, with warmer temperatures and smaller polar ice caps.
In a 2001 paper, Robert Bettinger at the University of California, Davis, and his colleagues suggested that these climatic shifts were crucial for the timing of agriculture’s origin. “,” they wrote, because the glacial climate was “extremely hostile to agriculture – dry, low in atmospheric CO2, and extremely variable on quite short time scales”.
However, they also argued that “in the Holocene, agriculture was, in the long run, compulsory”. This doesn’t follow for me at all, because our species has been around for 300,000 years or so – meaning we lived through several glacials and interglacials.
The actual timings of these cool and warm periods are quite tangled, because they weren’t the same on every continent. Very roughly (professional palaeoclimatologists, please don’t hurt me), this is what happened:
- Glacial: 390,000 to 340,000 years ago
- Interglacial: 340,000 to 320,000 years ago
- Glacial: 320,000 to 250,000 years ago
- Interglacial: 250,000 to 195,000 years ago
- The penultimate glacial: 195,000 to 130,000 years ago
- The last interglacial, also known as the Eemian: 130,000 to 115,000 years ago
- Last glacial period: 115,000 to 11,700 years ago
- Holocene interglacial: 11,700 years ago to present
This means our species has been around for at least three interglacials – possibly four, if we turn out to be a bit older than the current, wildly incomplete fossil record would suggest. But if interglacials are so ideal for the development of farming, why didn’t humans come up with it in either of the previous warm spells we lived through? It’s no use saying the last interglacial wasn’t very long, because it was still 15,000 years – longer than the entire Holocene to date.
I’m not saying climate change wasn’t a factor. But it can’t have been the only factor.
People, people everywhere
Perhaps, instead, farming was a response to food shortages. If you can’t get enough food by hunting and gathering, you might be able to get it from agriculture.
There are two mechanisms by which lack of food might have become a problem. First, ecosystems might have become depleted: for instance, humans might have hunted animals to extinction, depriving themselves of food in the long term. Second, human populations might have grown to the point that the existing ecosystems could no longer support them.
Neither looks immediately convincing. If anything, ecological conditions improved as the global climate warmed. A 2024 study of a site in northern China found that the warming climate led to a lusher ecosystem, which in turn improved the soil – ultimately .
Likewise, if population pressure was a factor, we’d expect to see evidence of population increases in the regions where farming was invented, but not in other places, in the centuries leading up to the onset of agriculture. Our records of past population trends are decidedly patchy, but in the eastern Mediterranean – one of the best-studied regions where people started farming – there is evidence that .
In recent years, researchers have started exploring more sociopolitical reasons for societies adopting farming. One suggestion is that , and away from communal living. On this view, people switched to farming because it gave them more direct control over their own food supplies and reduced their reliance on their communities.
In line with this, there is evidence that people were practising “proto-farming” for tens of thousands of years, cultivating a small number of crops while still getting most of their calories from hunting and gathering. The domestication of dogs – which may have begun as a means of using them for cooperative hunting – also seems to have happened long before the switch to farming. What seems to have happened is that some societies gradually shifted their emphasis, getting more calories from their gardens and fewer from other sources. In other words, people had been toying with farming for a long time, until eventually some of them went all in.
But we’re still left with a great big “why”. If farming was really a sociopolitical choice, not something driven by external factors, why did so many societies make the same choice at essentially the same time?
This is in danger of being an unsatisfying ending, so let’s speculate wildly. I find myself wondering whether Neanderthals or other hominins ever tried their hands at gardening, if only in a small way. I’m not aware of any evidence of it – I’m also not aware of anyone having seriously looked. We do have evidence of Neanderthals using medicinal plants and flavouring their food with wild herbs, not to mention processing and cooking their food. There was also a 2021 study suggesting they cleared a European forest to create a more open habitat. If they were lacking some crucial cognitive or physical capability to enable gardening, I’m not sure what it was. And if they did enjoy tending their own small gardens, that would have given our species a head start on creating full-blown farms.
Neanderthals, ancient humans and cave art: France
Embark on a captivating journey through time as you explore key Neanderthal and Upper Palaeolithic sites of southern France, from Bordeaux to Montpellier, with żěè¶ĚĘÓƵ’s Kate Douglas.
