The remarkable tale of how humans nearly didn’t conquer the world

It was a lonely and cold life. In the chilly wastes of northern Europe during the last glacial period, when the ice sheets had spread from the poles and the forests had been driven far south, a small group of humans clung to existence.

They roamed widely, between the British Isles in the west and what is now Poland in the east, yet there were only a few hundred of them. They hunted reindeer and woolly rhinoceros, and made distinctive leaf-shaped stone tools.

And then they disappeared. No living person carries DNA from this little population, so the leaf-shaped stones and a few bones are just about all that is left of them. We don’t know what they called themselves or what happened to them. All we know is that they didn’t make it.

We are now realising that stories like this are surprisingly common in prehistory. While it can be tempting to think of human evolution as a tale of progress and success, ultimately leading to a global population, the reality is that many lineages of our species died out and left no descendants.

Now, thanks to insights from ancient DNA, we are finally able to tell some of their stories. These lost peoples are also shining a light on why our once-insignificant branch of the wider human family tree survived and thrived.

Human evolution and exodus

The oldest known Homo sapiens – or what we call modern humans – lived in Africa, perhaps 350,000 years ago. Our understanding of the earliest members of our species is fragmentary, because we have hardly any fossils. But we know from genetics that all non-African people alive today seem to be descended from a single wave of migrants, who came out of Africa 50,000 to 60,000 years ago. After entering western Asia, some went east towards what are now India, China and Russia, while others headed north and west, to Europe.

All these lands were already inhabited by other species of human. The Neanderthals had been living in Europe and western Asia for hundreds of thousands of years. To the east were the mysterious Denisovans, and in the islands of South-East Asia there lived the diminutive Homo luzonensis and the “hobbits”, or Homo floresiensis. These would all soon disappear. The Neanderthals may have been the last survivors, clinging on in southern Spain until around 40,000 years ago.

We can see traces of the expansion of modern humans in the archaeological record. On the banks of the Don river in south-west Russia, archaeologists uncovered the remains of a man dubbed Kostenki-14, who lived 37,000 years ago. In 2014, DNA ***ysis revealed that he was closely related to today’s Europeans, and to some of the earliest modern humans in Europe. Further to the east, DNA from the 40,000-year-old remains of a man from Tianyuan cave in China showed that he belonged to a population that contributed to modern Asian peoples.

It is easy to interpret this as a story of modern humans triumphing. Thanks to our unique advantages – whether that is language, better tools, a more cooperative nature or something else – we outcompeted the Neanderthals and others, and today we reign supreme. We are the only remaining species of human, and there are over 8 billion of us.

Interbreeding with Neanderthals and Denisovans

Of course, it isn’t quite as simple as that. For one thing, modern humans interbred with the Neanderthals and Denisovans and many people today carry their DNA, so, in some sense, these extinct hominins are still with us.

And more to the point, modern humans didn’t have it all their own way. The first groups to enter Europe don’t seem to have endured there. At Bacho Kiro cave in Bulgaria, for instance, there are H. sapiens bones from 46,000 to 42,000 years ago. A 2021 genomic ***ysis found that they are related to present-day East Asian people, but there is no trace of their DNA in modern Europeans. They may have lived in Europe, but they didn’t survive there in the long term. The same seems to be true of modern humans who lived around 40,000 years ago in a cave in Romania.

“There is strong evidence that some early Homo sapiens groups that initially entered Europe did not contribute genetically to later populations,” says Priya Moorjani at the University of California, Berkeley. “Only molecular data revealed the absence of genetic continuity.”

One such lost group made those leaf-shaped artefacts. The distinctive tools were first discovered in the 1800s – at distant locations. British examples were called “Lincombian”, after Lincombe Hill in Torquay: set into this hill is Kents Cavern, where the artefacts were found. In Germany, the tools were discovered in Ilsenhöhle cave near the town of Ranis, so they were called “Ranisian”. In Poland, similar artefacts were found in a cave in the village of Jerzmanowice, so they were dubbed “Jerzmanowician”.

By the 1980s, archaeologists realised that these seemingly disparate objects were essentially identical, so they renamed them Lincombian-Ranisian-Jerzmanowician, or LRJ for short.

For a long time, we couldn’t be sure who made these tools, because they weren’t unambiguously blockociated with human remains. The mystery was finally solved in 2024, when a team led by Jean-Jacques Hublin at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, re-excavated Ilsenhöhle and recovered fragments of bone. The mitochondrial DNA within these revealed them to be from modern humans, who lived there around 45,000 years ago.

Archaeological evidence of lost lineages

The LRJ tools, it seems, were made by modern humans. Suggestive evidence from elsewhere now made sense: for instance, a 43,000-year-old jawbone from Kents Cavern had been tentatively identified as that of a modern human.

Later in 2024, researchers led by Arev Sümer, also at the Max Planck Institute for Evolutionary Anthropology, managed to obtain six nuclear genomes – the DNA from the heart of cells, as opposed to the more limited genetic material from mitochondria – from the Ilsenhöhle remains. Two seemed to be mother and daughter, and a third female was more distantly related to them. There were also three males who weren’t close relatives of the three females, but did belong to the same lineage.

There was a surprise, however. The team also sequenced a genome from a second site: Zlatý kůň in the Czech Republic, over 200 kilometres to the south-east. This individual proved to be a relative of two of the people from Ranis, despite living so far away. In other words, the people of Ranis and Zlatý kůň all belonged to the same extended family.

Furthermore, the team was able to estimate the size of the group by examining how similar the genomes were. They estimated that there were around 200 breeding adults in the Ranis/Zlatý kůň clan, and this had been steady for 15 generations. This figure was “extremely low given the large range from UK to Poland at the time”, study co-author Johannes Krause, also at the Max Planck Institute for Evolutionary Anthropology, said in a press conference.

The implication is both eerie and incredible: that a population that barely numbered in the hundreds was scattered over a distance of over 1500 km.

Who were these people? Their DNA points to them having dark skin, eyes and hair – exactly what we would expect for people whose recent ancestors lived in Africa. Based on animal bones found in Ilsenhöhle, the cave was mostly used by hibernating cave bears and denning hyenas, which indicates that the people only stayed there intermittently. Bones with cut marks, suggestive of butchery, point to the LRJ people eating a lot of reindeer, horse and rhinoceros (which still lived in Europe at the time).

What happened to them? We don’t know for sure, but can hazard some guesses.

The LRJ people were far from humanity’s ancestral home in Africa, in ecosystems that were relatively new to them. The planet was in a glacial period, and while the Mediterranean and Africa were sheltered from the worst of it, northern Europe was feeling the chill. “These groups were living really at the extremes, and were also vulnerable to climate change,” says Katerina Harvati at the University of Tübingen in Germany.

Then there is their tiny population. “When you have a small group, if you lose an individual that hunts very well or who socially keeps the group together, everything can easily fall apart,” says Sümer. “If there are only a few hundred of you, a few strokes of bad luck can spell doom – and if you don’t have any friendly neighbours, no one will come to your aid.”

In other words, the odds were stacked against the LRJ people and the other small bands of modern humans who were among the earliest waves to reach Europe. “For a very long time, we thought that [Homo] sapiens arrived in Europe by 42,000 years ago,” says Ludovic Slimak at the University of Toulouse in France. But it is clear that some modern humans got there earlier. “This colonisation is very likely to work as waves of populations coming to the west.”

In 2023, Slimak argued that there were three waves of modern humans that entered Europe between 55,000 and 42,000 years ago. The third was the one that established our species throughout Europe. Its members made distinctive “Proto-Aurignacian” artefacts. “We find it everywhere, in all Europe,” he says. “It’s a very large wave.”

The first two waves, in contrast, were smaller and less successful. “They go for some generations, some centuries, some millennia, in a part of Europe and then we lose their traces, and the genetics says we have no descendants of this population,” says Slimak. He says the LRJ people look to have been from the second wave.

The three waves all came from the eastern Mediterranean, argues Slimak. After migrating from Africa, modern humans lived continuously in that area, and from time to time some of them wandered further afield. This can be seen at Ksar Akil, a rock shelter near the coast of Lebanon. It contains 22.6 metres of sediments, divided into 36 layers, giving an unprecedented record of changing stone tool technology between about 50,000 and 30,000 years ago. The most recent layers contain Proto-Aurignacian tools; older layers harbour tools resembling the LRJ.

Evidence from a French cave

One such early migration has been doblockented at Grotte Mandrin, a cave overlooking the Rhône valley in southern France. Neanderthals lived there from before 80,000 years ago until 54,000 years ago. But then modern humans pop up in the archaeological record of the cave, in the form of one baby tooth from about 54,000 years ago. There are also distinctive stone points, which may have been arrowheads. Traces of soot from fires suggest that modern humans were there for about 40 years – after which they either died or left, and the Neanderthals returned. Only around 44,100 years ago – during Slimak’s third wave – did modern humans return to this area in numbers and permanently.

Larger and more connected populations may also help explain why the third wave succeeded in Europe. “This one is certainly a very large wave of population,” says Slimak. The archaeological record suggests Aurignacian populations were bigger, perhaps partly because of warmer conditions at 43,000 and 41,000 years ago. “They have a real success in terms of reproduction,” says Slimak. As populations became more dense, some people would have felt pressure to move, rapidly expanding their presence in the region. “You have a generation of people that have to move somewhere else where there are more proteins and less people.”

The larger populations may have also enabled Aurignacian people to maintain their cultural practices even as they moved long distances, which Slimak says is reflected in the uniformity of Aurignacian tools from different regions.

What about modern human groups elsewhere in the world? Did some of them also die out? There is tentative evidence from the Americas (see “Extinction in the Americas”), but for the most part we are stymied by bias in the archaeological record due to the fact that DNA doesn’t preserve well in hot and humid environments. “We have really good preservation of DNA in colder climates,” says Harvati, hence the many examples of local extinctions in Eurasia. “We don’t know what’s going on elsewhere.”

In particular, we have very little ancient DNA from Africa, the modern human heartland. “If you’re in one of the core areas, there’s always going to be other people around,” says Harvati. This may mean that African populations were safer, because they were always part of a network and could get help if they ran into trouble. But without DNA we can’t be sure.

Nevertheless, one lesson is clear: isolation is deadly. Over and over, groups that get “cut off from the bigger network of the societies around them” find themselves in trouble, says Harvati. And once the group size starts shrinking, their culture may die even if some of the people survive. “If you have a certain level of population collapse, then you also have loss of cultural knowledge as well,” she says. “If only a handful of individuals survive, then a lot of the traditions and the cultural knowledge of that group don’t necessarily make it, even if those people get absorbed in another group.”

People, it turns out, need people. And for our lineage – just one branch on a once-diverse family tree – this seems to have been the key to our survival and global ascendency.

North and South America were the last continents reached by our species, apart from Antarctica. People first entered the north-western part of North America in what is now Alaska, which is only a few tens of kilometres from the north-eastern corner of Eurasia.

However, there is a lot of disagreement and uncertainty about when and how people got there. In a 2022 review, Ben Potter at the University of Alaska Fairbanks and his colleagues argued that the evidence to date suggests that people began entering no earlier than 16,000 years ago and spread rapidly across both continents.

Other researchers have claimed that modern humans were there earlier. At Chiquihuite cave in Mexico, sediments laid down 33,000 years ago contained what appear to be stone tools. Meanwhile, footprints from White Sands National Park in New Mexico seem to be 21,000 to 23,000 years old – and earlier this year, the same site yielded marks that may have been left by crude wooden vehicles.

One interpretation is that there were early migrations into the Americas and those groups died out, just like the first modern humans in Europe. However, Potter is sceptical, arguing for instance that the Chiquihuite tools are so crude, they may be the result of natural processes such as rockfall, rather than human activity.

Nevertheless, evidence is emerging of lost lineages in the Americas. A study published in May looked at DNA from 21 people who lived in Colombia between 6000 and 500 years ago. This revealed a previously unknown group of hunter-gatherers, closely related to the first people to enter South America. They appear not to have contributed to any modern populations, and were ultimately replaced by groups that came from Central America.