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So, volcanoes are scary. I have vivid memories of visiting Pompeii and Herculaneum with my parents and seeing the twisted preserved corpses of people that were buried under the pyroclastic flow from Vesuvius. The people in question lived in what was, at the time, one of the most technologically advanced societies on the planet – yet they died in their thousands. Volcanoes are one of those phenomena that serve to remind us of how small we are , and remind us to treat nature with due caution and awe.
No doubt prehistoric peoples also died in volcanic eruptions. There are , where humans evolved. They include in Ethiopia, one of the few volcanoes in the world that has like you might see in the movies, and which lies in the Afar Region where many key hominin fossils have been found. As hominins migrated beyond Africa, they found their way to many volcanically active regions, such as Italy, Indonesia and South America. Some of those people, surely, got toasted.
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However, what I want to get into is whether volcanoes have ever done more than kill a few unlucky souls who happened to be nearby when they erupted. Has a volcanic eruption ever caused the extinction of a hominin species? There have been plenty of claims of such apocalyptic eruptions. As we’ll see, volcanoes have been linked to the extinctions of the Neanderthals and the hobbits – and one eruption was claimed to have taken our own species to the brink of extinction. But as we’ll see, there’s reason to be sceptical about all these ideas.
Volcano go boom
Of course, over the course of Earth’s history there have been examples of volcanic eruptions causing extinctions. The end-Permian extinction 252 million years ago was the worst mass extinction of the last half-billion years: it seems to have been caused by massive volcanic eruptions in what is now Siberia, which disrupted the chemistry of the oceans and atmosphere. The later end-Triassic extinction has also been linked to volcanic eruptions.
In both cases, the extinctions don’t occur because of the immediate impacts of the eruptions, like lava flows. These effects are too localised to cause widespread harm. The problems arise because the eruptions alter the climate and environment, sometimes across the entire planet. Only the biggest eruptions can do this.
One type of huge eruption is a large igneous province. This is when there are lots of ongoing eruptions over a wide area, sometimes lasting over a million years. The eruptions that caused the end-Permian extinction were a large igneous province. However, the most recent one happened in North America up to – long before hominins evolved. So large igneous provinces aren’t in the frame for causing any hominin extinctions.
The other type of mega-eruption is a supervolcano: a single discrete eruption that goes off with spectacular force, far larger than a normal eruption. A supervolcano eruption can cover a vast area with ash and cool the climate for years. There has not been a single supervolcano eruption in recorded history. The most recent was the Oruanui eruption of the Taupō volcano on the North Island of Aotearoa, or New Zealand, – millennia before humans reached the islands.
However, there have been several supervolcano eruptions during the 7 million years that hominins are known to have existed. Fortunately for our ancestors, most of them were in the Americas and happened before anyone got there. The Yellowstone supervolcano went off 8.7, 6.0, 4.5, 2.1 and 0.6 million years ago, and supervolcanoes in Argentina, Bolivia and Chile also erupted within the last 7 million years. However, there is no evidence that any of these had any effect on hominins.
And so we come to the Toba supervolcano, and the Toba bottleneck hypothesis.
Close to the brink
Today, Toba is a lake on the island of Sumatra in Indonesia. But 74,000 years ago it was a supervolcano that went off with spectacular force, releasing perhaps 2500 cubic kilometres of magma – which is almost double the volume of Mount Everest. Some researchers argue that the ensuing “volcanic winter” caused a population crash in our species, Homo sapiens, to the point that only about 10,000 of us survived.
This idea has an unusual history. The first person to propose it seems to have been science journalist Ann Gibbons, in . Gibbons was writing about genetic research that showed there was relatively little genetic variation in modern humans: this pointed to a population crash around 70,000 years ago, followed by rapid population growth around 50,000 years ago. In her story, she linked this to the Toba supervolcano, suggesting that it “triggered a climate change that made life tough for early humans about 70,000 years ago”.
To be clear, Gibbons did nothing wrong: she joined the dots in a reasonable way and made clear that this was just a suggestion, not a hard fact. Subsequently, . However, in the subsequent three decades the evidence has turned against the Toba bottleneck hypothesis.
For one thing, it’s not clear that the eruption’s climate impacts were powerful and long-lasting enough to cause major harm. Worse, there is no sign of animal extinctions – and if adaptable modern humans were badly affected, why weren’t other creatures? Furthermore, archaeological digs in India show modern humans living similar lifestyles before and after the ash fell, and a site in Ethiopia seems to record a couple of dry years, to which humans adapted. Finally, the genetic bottleneck seems to be less to do with population shrinkage and more to do with a “founder effect” – basically, one small population in Africa expanded into the rest of the world, carrying their genetic traits with them. But this doesn’t mean the total human population at that time was especially small.
Mount Doom
Leaping forward in time a few millennia, we come to the hobbit extinction. Homo floresiensis were small-bodied hominins, barely a metre tall, that lived on the island of Flores, also in Indonesia (but further east). They seem to have lived there between 190,000 and 50,000 years ago.
In 2018 I reported on research that showed several large animals disappeared from the Flores fossil record at the same time as the hobbits, 50,000 years ago. The losses included dwarf elephants, which seem to have been crucial for the ecosystem: hobbits and other animals ate them. The researchers found traces of a volcanic eruption that caused a pyroclastic flow 50,000 years ago, which may have killed off the elephants and damaged the ecosystem.
However, even the researchers themselves did not pin the hobbit extinction solely on the volcanic eruption: the dwarf elephants and hobbits had survived many big eruptions before. Instead, they pointed to the arrival of modern humans, with their more advanced hunting techniques, as a possible factor in the extinction of the elephants – and thus the hobbits.
Earlier this month, żěè¶ĚĘÓƵ contributor Christa LestĂ©-Lasserre reported on a reconstruction of changing rainfall patterns on Flores. This revealed a long-term drying trend just before the extinctions, which may have created intolerable pressures on the elephants and hobbits.
This is a tangled tale and we can’t yet untangle it. I would not be surprised if the volcanic eruption was a factor in the hobbit extinction – but I think it would have been the straw that broke the camel’s back, not the ten-tonne weight that weakened it.
Neanderthals versus volcanoes
And so we come, finally, to the most famous hominin extinction of all: the Neanderthals. After living in Europe and Asia for hundreds of thousands of years, the Neanderthals disappeared – probably around 40,000 years ago, although there are claims that isolated populations survived a bit longer.
In December, I wrote about a pair of studies that used ancient genomes to reconstruct the interbreeding between Neanderthals and modern humans. It turns out this happened between 50,500 and 43,500 years ago, probably somewhere in the eastern Mediterranean. A few millennia later, the Neanderthals died out – and so, it seems, did the few modern human populations that had made it into Europe by that time.
During the press conference about the studies, at the Max Planck Institute for Evolutionary Anthropology in Germany offered an explanation for the demise of the Neanderthals and modern humans in Europe. You guessed it: a volcano.
Or rather, a supervolcano. Under the Bay of Naples in Italy, there lies a huge magma chamber called Campi Flegrei. This erupted in a big way around 39,000 years ago, in what’s now called the Campanian Ignimbrite eruption, and which covered much of eastern Europe with volcanic ash. Krause speculated that the Campanian Ignimbrite eruption wiped out both the last Neanderthals and the small Homo sapiens populations in Europe at the time – something have over the years.
I’m intrigued but cautious. For starters, the timing doesn’t seem quite right. If we take the dates at face value, the eruption was 1000 years after the last confirmed appearance of the Neanderthals, so it was too late to matter. That said, both the dates have uncertainties.
The geography is perhaps a bigger issue. The debris from the eruption , falling out over eastern Europe north of the Black Sea and out into what is now Russia. Meanwhile, the last Neanderthals were in western Europe – .
There’s probably something quite revealing about human psychology in our tendency to look for single, dramatic causes for extinctions – which conservationists will tell you are almost always caused by multiple factors. Our Human Story’s editor Chelsea Whyte wrote a story in 2022 about the “Cat Gap”: a period of over 6 million years when cat-like animals disappeared from North America. It was tentatively linked to a big volcanic eruption, but it turned out other factors like climate change and lack of food were more important.
Dangerous as volcanoes are, I remain unconvinced that they have ever wiped out a hominin species. Hunter-gatherer populations are too mobile and dispersed to be killed en masse by eruptions.
In fact, there is evidence that hominins regularly lived near volcanoes and climbed them shortly after they erupted. On the Roccamonfina volcano in Italy, there are footprints preserved in solidified volcanic ash from 385,000 to 325,000 years ago. We can’t be sure who made them, although Neanderthals are good candidates. There are no children, suggesting the adults knew the area was dangerous. However, they seem to have been walking at a relaxed speed – and some of them were heading uphill.
