A reconstruction of a late Neanderthal from El Salt, southeastern Spain. Some of the last Neanderthals may have lived in the Iberian peninsula. Our closest human relatives may have died out thanks to a combination of factors, including isolation, inbreeding and competition from modern humans, emerging research suggests.
(Image credit: Fabio Fogliazza)
A complex picture of how Neanderthals died out, and the role that modern humans played in their disappearance, is emerging.
About 37,000 years ago, Neanderthals clustered in small groups in what is now southern Spain. Their lives may have been transformed by the eruption of the Phlegraean Fields in Italy a few thousand years earlier, when the caldera's massive explosion disrupted food chains across the Mediterranean region.
They may have gone about their daily life: Crafting stone tools, eating birds and mushrooms, engraving symbols on rocks, and creating jewelry out of feathers and shells.
They likely never realized they were among the last of their kind.
But the story of their extinction actually begins tens of thousands of years earlier, when the Neanderthals became isolated and dispersed, eventually ending nearly half a million years of successful existence in some of the most forbidding regions of Eurasia.
By 34,000 years ago, our closest relatives had effectively gone extinct. But because modern humans and Neanderthals overlapped in time and space for thousands of years, archaeologists have long wondered whether our species wiped out our closest relatives. This may have occurred directly, such as through violence and warfare, or indirectly, through disease or competition for resources.
Now, researchers are solving the mystery of how the Neanderthals died out — and what role our species played in their demise.
(Image credit: DEA / A. DAGLI ORTI/De Agostini via Getty Images)
"I think the fact is, we do know what happened to Neanderthals, and it is complex," Shara Bailey, a biological anthropologist at New York University, told Live Science.
Decades of research has revealed a complex picture: A perfect storm of factors — including competition among Neanderthal groups, inbreeding and, yes, modern humans — helped erase our closest relatives from the planet.
The rise and demise of our closest human relatives
The modern story of Neanderthals began in 1856, when quarry workers found a strange-looking, not-quite-human skull in Germany's Neander Valley.
Archaeologists gave the skull a new species name: Homo neanderthalensis. And in the early decades after the discovery, researchers assumed the creatures were knuckle-dragging brutes. This depiction was based on a flawed reconstruction of a skeleton of an old Neanderthal man, whose spine was deformed by arthritis, found at La Chapelle-aux-Saints in France.
Now, more than 150 years of archaeological and genetic evidence makes it clear that these early human relatives were much more advanced than we originally thought. Neanderthals crafted sophisticated tools, may have made art, decorated their bodies, buried their dead, and had advanced communication abilities, albeit a more primitive kind of language than modern humans used. What's more, they survived for hundreds of thousands of years in the hostile climates of Northern Europe and Siberia.
Before they met in Eurasia, Neanderthals and modern humans last shared an ancestor in the Middle Pleistocene epoch, between 600,000 and 800,000 years ago. Modern humans and Neanderthals evolved separately; Neanderthals adapted to cold climates with sturdier bodies, larger faces and different metabolic processes than the taller, thinner Homo sapiens. Neanderthals evolved in Eurasia about 400,000 years ago, and H. sapiens arrived significantly later, evolving in Africa 300,000 years ago and settling in Europe between about 55,000 and 45,000 years ago.
Based on archaeological evidence from sites from Russia to the Iberian Peninsula, Neanderthals and modern humans likely overlapped for at least 2,600 years — and perhaps as long as 7,000 years — in Europe. That overlap occurred during a bleak period in Neanderthal history that ended with their downfall — raising the question of whether modern humans were responsible for killing them off.
But the story of Neanderthal life — and extinction — is one of regional variation, said Tom Higham, an archaeological scientist at the University of Vienna.
"In some areas, for example, we see that humans arrive to empty spaces in Europe where there aren't any Neanderthals anymore, seemingly," Higham told Live Science. "And in other places, we see that there's probably an overlap that happens … we know that people are interbreeding."
The first empirical proof of that interbreeding was found in 2010, when a Neanderthal genome was sequenced. Since then, genetic analysis has shown that Neanderthals and modern humans shared much more than a geographic area — we regularly exchanged DNA back and forth, meaning there is a bit of Neanderthal in every modern human population studied to date.
Already on the brink
When modern humans and Neanderthals met tens of thousands of years ago, the latter were probably already in trouble. Genetic studies suggest that Neanderthals had lower genetic diversity and smaller group sizes than modern humans, hinting at a potential reason for Neanderthals' demise.
"Genetically, one big clue that we get is this idea of heterozygosity," Omer Gokcumen, an evolutionary genomicist at the University at Buffalo, told Live Science. An individual receives two copies, or alleles, of a gene from each parent. Individuals are "heterozygous" for a given gene if they inherit a different allele from each parent. In Neanderthals' small communities, which contained fewer than 20 adults in each group, more inbreeding occurred. That meant fewer of them inherited different versions of a gene from each parent and, therefore, had low heterozygosity.
"Neanderthals may have suffered for that — what they call a mutational burden," Gokcumen said. Genetic research suggests Neanderthals had many problematic mutations that likely affected their survival, including a rare blood type. "Because of their small population size, they couldn't actually breed these bad alleles out, and their kids may actually be sickly at the end," Gokcumen said.
Any population of animals survives into the future through successful reproduction and rearing of offspring. Researchers estimating the mortality rates of Neanderthal infants have found that a decrease of even 1.5% in the survivorship of these children could result in population extinction within 2,000 years, April Nowell, a Paleolithic archaeologist at the University of Victoria in British Columbia, told Live Science.
"I think the fact is, we do know what happened to Neanderthals, and it is complex," Shara Bailey, a biological anthropologist at New York University, told Live Science.
Decades of research has revealed a complex picture: A perfect storm of factors — including competition among Neanderthal groups, inbreeding and, yes, modern humans — helped erase our closest relatives from the planet.
The rise and demise of our closest human relatives
The modern story of Neanderthals began in 1856, when quarry workers found a strange-looking, not-quite-human skull in Germany's Neander Valley.
Archaeologists gave the skull a new species name: Homo neanderthalensis. And in the early decades after the discovery, researchers assumed the creatures were knuckle-dragging brutes. This depiction was based on a flawed reconstruction of a skeleton of an old Neanderthal man, whose spine was deformed by arthritis, found at La Chapelle-aux-Saints in France.
Now, more than 150 years of archaeological and genetic evidence makes it clear that these early human relatives were much more advanced than we originally thought. Neanderthals crafted sophisticated tools, may have made art, decorated their bodies, buried their dead, and had advanced communication abilities, albeit a more primitive kind of language than modern humans used. What's more, they survived for hundreds of thousands of years in the hostile climates of Northern Europe and Siberia.
Before they met in Eurasia, Neanderthals and modern humans last shared an ancestor in the Middle Pleistocene epoch, between 600,000 and 800,000 years ago. Modern humans and Neanderthals evolved separately; Neanderthals adapted to cold climates with sturdier bodies, larger faces and different metabolic processes than the taller, thinner Homo sapiens. Neanderthals evolved in Eurasia about 400,000 years ago, and H. sapiens arrived significantly later, evolving in Africa 300,000 years ago and settling in Europe between about 55,000 and 45,000 years ago.
Based on archaeological evidence from sites from Russia to the Iberian Peninsula, Neanderthals and modern humans likely overlapped for at least 2,600 years — and perhaps as long as 7,000 years — in Europe. That overlap occurred during a bleak period in Neanderthal history that ended with their downfall — raising the question of whether modern humans were responsible for killing them off.
But the story of Neanderthal life — and extinction — is one of regional variation, said Tom Higham, an archaeological scientist at the University of Vienna.
"In some areas, for example, we see that humans arrive to empty spaces in Europe where there aren't any Neanderthals anymore, seemingly," Higham told Live Science. "And in other places, we see that there's probably an overlap that happens … we know that people are interbreeding."
The first empirical proof of that interbreeding was found in 2010, when a Neanderthal genome was sequenced. Since then, genetic analysis has shown that Neanderthals and modern humans shared much more than a geographic area — we regularly exchanged DNA back and forth, meaning there is a bit of Neanderthal in every modern human population studied to date.
Already on the brink
When modern humans and Neanderthals met tens of thousands of years ago, the latter were probably already in trouble. Genetic studies suggest that Neanderthals had lower genetic diversity and smaller group sizes than modern humans, hinting at a potential reason for Neanderthals' demise.
"Genetically, one big clue that we get is this idea of heterozygosity," Omer Gokcumen, an evolutionary genomicist at the University at Buffalo, told Live Science. An individual receives two copies, or alleles, of a gene from each parent. Individuals are "heterozygous" for a given gene if they inherit a different allele from each parent. In Neanderthals' small communities, which contained fewer than 20 adults in each group, more inbreeding occurred. That meant fewer of them inherited different versions of a gene from each parent and, therefore, had low heterozygosity.
"Neanderthals may have suffered for that — what they call a mutational burden," Gokcumen said. Genetic research suggests Neanderthals had many problematic mutations that likely affected their survival, including a rare blood type. "Because of their small population size, they couldn't actually breed these bad alleles out, and their kids may actually be sickly at the end," Gokcumen said.
Any population of animals survives into the future through successful reproduction and rearing of offspring. Researchers estimating the mortality rates of Neanderthal infants have found that a decrease of even 1.5% in the survivorship of these children could result in population extinction within 2,000 years, April Nowell, a Paleolithic archaeologist at the University of Victoria in British Columbia, told Live Science.
The birth of modern Man
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