The 2023 discoveries that made us rethink the story of human evolution

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At this point it’s a truism that the story of human evolution is being rethought. Discoveries in recent years have forced us to rethink many crucial points, such as how old our species is – about 300,000 years old as opposed to 200,000 – and what extinct hominins like the Neanderthals were really like.

2023 was equally dizzying: discoveries continued to come thick and fast. But because there are so many species and eras involved, it’s hard to discern the common threads linking them – at least, beyond “we found out some more stuff”.

However, I do think it’s possible to draw out some overall messages from the blizzard of archaeological finds. Two things stand out to me. One is the growing evidence that many supposedly “advanced” behaviours, such as architecture and art, can be traced much further back in time than we thought, often to hominins that existed before modern humans. And the other is that we have badly misunderstood gender roles in prehistoric societies, imposing patriarchal values onto cultures that had very different ideas about how women should behave.

Ancient achievements

Let’s start with architecture. At Kalambo Falls in Zambia, researchers found buried logs that had been shaped with stone tools so that they interlocked. They seem to have once been part of a larger structure, perhaps a building. Which would be unsurprising if they weren’t 476,000 years old. That’s almost 200,000 years before our species, Homo sapiens, evolved.

Extinct hominins also managed to settle in extreme places. For instance, we now know that hominins like the Denisovans lived on the frigid heights of the Tibetan plateau 200,000 years ago – upending the old notion that the plateau was only settled by modern humans around 3600 years ago.

Art also seems to have been invented by older hominins. We already had evidence that Neanderthals painted on cave walls, and 2023 saw more Neanderthal art from La Roche-Cotard cave in France. Even earlier species like Homo erectus may also have made art, for example by engraving patterns on shells.

By far the most contentious claim in this area is that Homo naledi made art. H. naledi lived around 250,000 years ago, making it a contemporary of our species. However, it had quite a small brain, typical of older hominins – and was therefore, according to palaeoanthropological dogma, incapable of complex behaviours.

Nevertheless, in the Rising Star cave system in South Africa where the H. naledi remains were found, researchers have found what seem to be etchings on the cave walls, though these have yet to be firmly dated. They also claim to have found evidence of H. naledi burying their dead in the cave. These assertions were the subject of a Netflix documentary, Cave of Bones.

To say these claims are controversial is to understate the situation. Many researchers say the evidence presented so far is completely inadequate to support them. The dispute has only been heightened by the way the results were released, in a non-traditional journal that publishes peer reviews publicly alongside the paper.

My views on the H. naledi controversy are complicated. I do think more evidence is needed: in particular, I want to know how old the engravings are. At the same time, I think the species’ small brains are a distraction. Palaeoanthropologists got fixated on brain size because it was what they could see: if what you have is skeletons, then all you know about brains are their shapes and sizes. But other properties like the brain’s internal wiring are surely equally important and may explain how a species like H. naledi could do complicated things despite their small brains.

In a sense, we shouldn’t be surprised that so many of these behaviours had their origins in older, extinct hominins. Evolution usually works by gradual steps, and so does technology – the first birds weren’t great at flying, and the first mobile phones weren’t great at, well, anything really.

The idea that there was a sudden explosion of intelligence and creativity at some point in our evolution isn’t inherently ridiculous: sometimes a system hits a tipping point and undergoes runaway change. But there was never that much evidence that human evolution worked this way. Instead, it seems that Homo erectus, the Neanderthals and many others all walked so we could run.

Alternative societies

One way or another, the H. naledi story is going to be an example of letting our preconceptions get in the way of the evidence. The same is true for our ideas about gender in prehistory. Archaeology was invented by societies with sexist ideas, and those notions bled into the research (see also: scientific racism and homophobia). Researchers are now trying to unpick this stuff, and 2023 saw some significant steps.

Perhaps the most dramatic was the demolition of “Man the Hunter”. This was the idea, promoted for decades, that in most prehistoric societies the men went out to hunt and the women stayed home. However, a meta-analysis published in June compiled data on several dozen foraging societies and found women hunted in 80 per cent of them. In line with this, it emerged that an ancient spear-throwing tool called an atlatl enables women to launch projectiles at the same speed as men.

We have also seen growing evidence of women occupying positions of power in ancient societies. The Viking queen Thyra may have helped unify Denmark in the 900s. Going further back, an Iberian leader from around 4000 years ago turned out to be female, not male as many had assumed, when proteins in her teeth were analysed.

So I want to end 2023 on a hopeful note. The more we learn about past societies, the more our preconceptions about the ways society “has to be” turn out to be wrong. Inequality, authoritarianism and patriarchy aren’t inevitable. They’re choices, and prehistory shows us that we can choose differently.

Source: Humans - newscientist.com