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According to "Neanderthals: Facts About Our Extinct Human Relatives" (Szalay, 2013), Neanderthals dominated Europe during the last Ice Age, but may have died out before the arrival of Homo Sapiens (according to research detailed in "Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia" (Wood et al. 2012).
There are a number of theories floating around in the literature - everything from inability to adapt to climate change to dietary deficiencies.
What does the latest research suggest as the cause of the Neanderthal extinction?
(refereed papers would be appreciated)
This is one of those active areas of research where there isn't a lot of consensus among researchers. There isn't even consensus as to whether it was an extinction in the strictest sense, because we now have evidence from genomic research that Neanderthals interbred with modern humans. Research is still being done on a lot of different hypotheses.
This article by K. Harvati is a decent short summary of the current state of the field, and includes references to recent articles.
Neanderthals became extinct around 40,000 years ago. This timing, based on research published in Nature in 2014, is much earlier than previous estimates, and derives from improved radiocarbon-dating methods analyzing 40 sites from Spain to Russia.  Evidence for continued Neanderthal presence in the Iberian Peninsula 37,000 years ago was published in 2017. 
Various hypotheses on the causes of Neanderthal extinction implicate:
- parasites and pathogens
- competitive replacement 
- extinction by interbreeding with early modern human populations
- natural catastrophes
- failure or inability to adapt to climate change
It seems unlikely that any single one of these hypotheses is sufficient on its own rather, multiple factors probably contributed to the demise of an already low population.
It Was NOT Climate Change That Caused Neanderthal Extinction
Researchers sampled this 50-cm long stalagmite in the Pozzo Cucù cave, in the Castellana Grotte area (Bari) and they carried out 27 high-precision datings and 2,700 analyses of carbon and oxygen stable isotopes. Credit: O. Lacarbonara
Homo Neanderthaliensis did not become extinct because of changes in climate. At least, this did not happen to the several Neanderthals groups that lived in the western Mediterranean 42,000 years ago. A research group of the University of Bologna came to this conclusion after a detailed paleoclimatic reconstruction of the last ice age through the analysis of stalagmites sampled from some caves in Apulia, Italy.
The researchers focused on the Murge karst plateau in Apulia, where Neanderthals and Homo Sapiens coexisted for at least 3,000 years, from approximately 45,000 to 42,000 years ago. This study was published in Nature Ecology & Evolution. Data extracted from the stalagmites showed that climate changes that happened during that time span were not particularly significant. “Our study shows that this area of Apulia appears as a ‘climate niche’ during the transition from Neanderthals to Homo Sapiens” explains Andrea Columbu, researcher and first author of this study. “It doesn’t seem possible that significant climate changes happened during that period, at least not impactful enough to cause the extinction of Neanderthals in Apulia and, by the same token, in similar areas of the Mediterranean.”
The Climate Change Hypothesis
The hypothesis that a changing climate was a factor in Neanderthals extinction (that happened, in Europe, nearly 42,000 years ago) found considerable support among the scientific community. According to this theory, during the last ice age, sharp and rapid changes in climate were a decisive factor in Neanderthals’ extinction because of the increasingly cold and dry weather.
We can find confirmation of these sharp changes in the analysis of ice cores from Greenland and from other paleoclimatic archives of continental Europe. However, when it comes to some Mediterranean areas where Neanderthals had lived since 100,000 years ago, the data tell a different story. The Western Mediterranean is rich in prehistorical findings and, until now, no one ever carried out a paleoclimatic reconstruction of these Neanderthals-occupied areas.
The Importance of Stalagmites
Where to find answers about the climate past of the Western Mediterranean? The research group of the University of Bologna turned to the Murge plateau in Apulia. “Apulia is key to our understanding of anthropological movements: we know that both Neanderthals and Homo Sapiens lived there approximately 45,000 years ago,” says Andrea Columbu. “Very few other areas in the world saw both species co-existing in a relatively small space. This makes the Murge plateau the perfect place to study the climate and the bio-cultural grounds of the transition from Neanderthal to Sapiens.”
How is it possible to provide a climate reconstruction of such a remote period? Stalagmites have the answer. These rock formations rise from the floor of karst caves thanks to ceiling water drippings. “Stalagmites are excellent paleoclimatic and paleoenvironmental archives,” explains Jo De Waele, research coordinator and professor at the University of Bologna. “Since stalagmites form through rainwater dripping, they provide unquestionable evidence of the presence or absence of rain. Moreover, they are made of calcite, which contains carbon and oxygen isotopes. The latter provide precise information about how the soil was and how much it rained during the formation period of stalagmites. We can then cross these pieces of information with radiometric dating, that provide an extremely precise reconstruction of the phases of stalagmites’ formation.”
A (Relatively) Stable Climate
The pace at which stalagmites formed is the first significant result of this study. Researchers found out that Apulian stalagmites showed a consistent pace of dripping in the last and previous ice ages. This means that no abrupt change in climate happened during the millennia under investigation. A draught would have been visible in the stalagmites.
Among all the stalagmites that were analyzed, one was particularly relevant. Researchers sampled this 50-cm long stalagmite in the Pozzo Cucù cave, in the Castellana Grotte area (Bari) and they carried out 27 high-precision datings and 2,700 analyses of carbon and oxygen stable isotopes. According to dating, this stalagmite formed between 106,000 and 27,000 years ago. This stalagmite represents the longest timeline of the last ice age in the western Mediterranean and in Europe. Moreover, this stalagmite did not show any trace of abrupt changes in climate that might have caused Neanderthals’ extinction.
“The analyses we carried out show little variation in rainfall between 50,000 and 27,000 years ago, the extent of this variation is not enough to cause alterations in the flora inhabiting the environment above the cave,” says Jo De Waele. “Carbon isotopes show that the bio-productivity of the soil remained all in all consistent during this period that includes the 3,000 years-long coexistence between Sapiens and Neanderthals. This means that significant changes in flora and thus in climate did not happen.”
The Technology Hypothesis
The results seem to show that the dramatic changes in the climate of the last ice age had a different impact on the Mediterranean area than in continental Europe and Greenland. This may rule out the hypothesis that climate changes are responsible for Neanderthals dying out.
How do we explain their extinction after a few millennia of coexistence with Homo Sapiens? Stefano Benazzi, a paleontologist at the University of Bologna and one of the authors of the paper, provides an answer to this question. “The results we obtained corroborate the hypothesis, put forward by many scholars, that the extinction of Neanderthals had to do with technology,” says Benazzi. “According to this hypothesis, the Homo Sapiens hunted using a technology that was far more advanced than Neanderthals’, and this represented a primary reason to Sapiens’ supremacy over Neanderthals, that eventually became extinct after 3,000 years of co-existence.”
The Authors of the Study
The study was published in Nature Ecology & Evolution with the title “Speleothem record attests to stable environmental conditions during Neanderthal- modern human turnover in southern Italy.” Representing the University of Bologna, we have Andrea Columbu, Veronica Chiarini, and Jo De Waele from the Department of Bioloical, Geological and Environmental Sciences, and Stefano Benazzi from the Department of Cultural Heritage.
Other scholars also participated in the study: from the University of Innsbruck (Austria) where the isotopic analyses were carried out, from Melbourne University (Australia) and Xi’an Jiaotong University (China), that carried out the radiometric dating.
Grotte di Castellana, the Apulian Speleology Association and, for the major part, local speleology groups provided funding for this study.
Reference: “Speleothem record attests to stable environmental conditions during Neanderthal–modern human turnover in southern Italy” by Andrea Columbu, Veronica Chiarini, Christoph Spötl, Stefano Benazzi, John Hellstrom, Hai Cheng and Jo De Waele, 6 July 2020, Nature Ecology & Evolution.
The Institute for Creation Research
How did Neanderthals go extinct? Four researchers from the Netherlands recently published the results of their computer-modeled human populations in the journal PLOS ONE. 1 The findings show that small Neanderthal population sizes would have caused them to become extinct in just 10,000 years. How did Neanderthals survive the 400,000 years they were supposedly on Earth?
Neanderthals were real people. Hundreds of recovered bones show big brow ridges, sloping foreheads, and thick upper arms. They buried their dead, made music, jewelry, used makeup, and built tools for hunting and even surgery. They intermarried with other more modern-looking people. Their fully human DNA had variations that many people groups share today. Some of us still have Neanderthal body traits. Our shared DNA fits our shared traits.
Faced with all this evidence, secularists find it almost impossible to stick with the old story that modern men evolved from Neanderthals. Instead, Neanderthals went extinct while other people groups multiplied (similar to the extinction of cave bears amid the fruitfulness of black, brown, grizzly, polar, and other bear varieties). Modern humans and Neanderthals lived side by side, at least in time. But as a distinct people group, Neanderthals went extinct and nobody knows exactly why.
Whoever wishes to address this problem should admit that science cannot directly solve it without a time machine. Forensic science can only evaluate possibilities. One long-held idea holds that ancient non-Neanderthals warred against them and drove them to extinction. Others suggest cold climates did them in. 2 If so, then why did their neighbors survive? Perhaps Neanderthals suffered too much disease. 3 With no data to back them, these ideas remain possible but unprovable.
This new report suggests that no wars were needed to exterminate Neanderthals. If they lived in relatively small and happy populations, they would still have gone extinct all by themselves. The Dutch team modeled the effect of three factors on digital population sizes of 50, 100, 250, and 1,000 individuals. Inbreeding concentrates recessive traits and accelerates genetic decline.
Allee effects (a decline in individual fitness at a low population size that can result in population thresholds that can lead to extinction) describe how population sizes influence reproduction. For example, females in a small population may have a hard time finding a mate. They would reproduce less often, leading eventually to catastrophic population decline. Finally, chance-based mishaps like fires, floods, and droughts can ruin small populations in a hurry&mdashcontributing to Allee effects. The team&rsquos results showed that just one of these three factors was enough to cause extinction.
The study authors wrote, &ldquoIn sum, Allee effects probably were a key, and perhaps even a sufficient, factor in the demise of Neanderthals.&rdquo 1
Allee effects were just one factor, yet enough to doom Neanderthals in 10,000 years. This led the study authors to ask, &ldquoIf Neanderthals lived in small populations since
400 kya [400,000 years ago], why did it take so long for them to become extinct?&rdquo 1 The weaknesses in the answers they gave suggest that questioning the 400k year-old premise should instead occupy their minds.
Their answers boiled down to hand-waving just-so stories. For example, they wrote, &ldquoThere is nothing unusual about the persistently small size of Neanderthal populations. Hominin populations likely were small throughout the Pleistocene.&rdquo 1 Should this ease reader discomfort over the mismatch between their modeled Neanderthals and ancient Neanderthal age assignments? Not at all, because the argument is circular. It says that we expect 400,000 year-old Neanderthals because other small populations lasted for that long, too. What scientist was there to record how long any of those populations lived?
The study authors&rsquo circular argument also has nothing to do with their finding of extinction via Allee effects in only 10,000 years. They should instead show why Allee effects alone wouldn&rsquot also have brought so-called hominids to extinction in 10,000 years or less.
Vast ages rest upon a presumed evolutionary past, not observational science. An objective scientist might also ask why the earth has only a few thousand years&rsquo worth of Neanderthal and early human fossil remains instead of hundreds of thousands. 4
What other explanation do they offer to explain how Neanderthal populations somehow avoided Allee effects for 400,000 years? They wrote, &ldquoEnvironmental conditions, for instance, might be favorable and alleviate the stress induced by demographic stochasticity [random calamities].&rdquo 1 What are the odds that world offered no lethal droughts, volcanic explosions, landslides, or diseases for 400,000 supposed years? The key word in this explanation is might. Thinking along these lines, a duck might fly across the Pacific Ocean and back. But probably not.
Especially not when faced with so many obstacles. The PLOS ONE study lists an array of obstacles to small-population survival. Its authors wrote, &ldquoSo even&hellipwhen Allee effects are relatively small, random events might lead to extinction.&rdquo 1 The longer the age assignment, the greater the odds of extinction from random events. The study authors wrote, &ldquoBut in the very long run, such an unfavorable scenario eventually will take place.&rdquo 1 400,000 years ought to count as a very long run indeed. Neanderthals would have gone extinct long before their allotted time.
In addition to random events and time working against those modeled Neanderthal populations, &ldquothe presence of modern humans in Eurasia would have accelerated a process that, at some point, was likely to have occurred anyway.&rdquo 1 That is, the process of extinction. The study authors also name dramatic climate shifts, disease epidemics, and resource competition as possibly having worked against Neanderthal survival. Their 400,000-year story needs no more ways to kill off the population. It needs ways to sustain it. Where are these ways?
Eyewitness records from the Bible&rsquos writers, not nature-only philosophy, supply a biblical timeline. It would place Neanderthal cave burials soon after Noah&rsquos Flood only several thousand years ago. This brief stay on planet Earth fits the short time that Allee effects alone indicate for small populations. Adopting a shorter overall timeline removes the mismatch between so many population-dooming effects and 400,000 supposed years of somehow avoiding them all. It even explains why we find so few fossils of ancient peoples. Human fossils and population models both fit the Scripture.
Dawn of Humanity
Becoming Human Part 1
In August 1856, in the German valley of Neander—Neanderthal in German—men cutting limestone for the Prussian construction industry stumbled upon some bones in a cave. Looking vaguely human, the bones—a piece of a skull, portions of limbs, and fragments of shoulder blades and ribs—eventually made their way to an anatomist in Bonn named Hermann Schaafhausen.
Schaafhausen pored over the fossils, observing their crests and knobs. He noticed that the bones had the overall shape youɽ expect from a human skeleton. But some bones had strange features, too. The skullcap, for example, sported a heavy brow ridge, hanging over the eyes like a boney pair of goggles. It was, at once, human and not.
The Neanderthal Man challenged Schaafhausen with a simple yet profound question: Was it a human, or did it belong to another species?
It's been over 150 years since the bones first emerged from the Neander Valley—a time during which we've learned a vast amount about human evolution. Today, scientists can even scan the genomes of Neanderthals who died 50,000 years ago. And yet the debate still rages. It's a debate that extends beyond Neanderthals, forcing us to ask what it means to be a species at all.
Variations on a theme
The Neander Valley bones were a sensation as soon as Schaafhausen published his report on them in 1857, because nothing like them had been seen before. Earlier in the 1800s, cave explorers had found ancient human bones, sometimes lying next to fossils of cave bears and other extinct animals. Naturalists had a hazy sense from such bones that humanity had been around for quite a long time. But the idea that humans—or any other species—had evolved was scandalous. Darwin would not publish The Origin of Species for another two years. Instead, naturalists saw humans as a species distinct from chimpanzees, gorillas, and all other primate species. We were distinct today, and we had been distinct since creation.
The youngest Neanderthal fossils date to 28,000 years ago.
Within the human species, European anatomists divided people into races. They often ranked Europeans as the noblest race, considering the others barely better than apes. To justify this racist view of humanity, anatomists searched for clear-cut differences between the skeletons of different races—the size of skulls, the slopes of brows, the width of noses. Yet their attempts to neatly sort people into groups were bedeviled by the blurry variations in our species. Within a single so-called race, people varied in color, height, and facial features. Schaafhausen knew, for example, about a skull dug up from an ancient grave in Germany that "resembled that of a Negro," as he wrote.
A barbarian (with sword) attacking a Roman legionary in a second-century relief. Neanderthals wouldn't have been out of place amongst such savage sorts, Schaafhausen believed.
On this confusing landscape Schaafhausen tried find a place for the Neanderthal Man. He decided that its heavy brow didn't disqualify it as a human. To back up this diagnosis, he relied on stories of ancient European savagery. "Even of the Germans," Schaafhausen wrote in his 1857 report on the Neander Valley bones, "Caesar remarks that the Roman soldiers were unable to withstand their aspect and the flashing of their eyes, and that a sudden panic seized his army."
Schaafhausen searched historical records for other clues of Europe's monstrous past. "The Irish were voracious cannibals, and considered it praiseworthy to eat the bodies of their parents," he wrote. In the 1200s, ancient tribes in Scandinavia still lived in the mountains and forests, wearing animal skins, "uttering sounds more like the cries of wild beasts than human speech."
Surely, in such a savage place, this heavy-browed Neanderthal would have fit right in.
A distinctive creature
When Schaafhausen published his report, many other naturalists tried to make sense of the bones for themselves. After Darwin published his theory of evolution in 1859, new possibilities arose: Perhaps humans evolved from Neanderthals, or perhaps they were both descended from a common ancestor.
Thomas Huxley, Darwin's great champion in England, argued that Neanderthals were human, pointing to the thick foreheads of living Australian Aborigines. William King, an Irish geologist, disagreed. In an 1864 paper, "The Reputed Fossil Man of the Neanderthal," he pointed to a long list of traits that separated it from living humans—from its tightly curved ribs to the massive sinuses in its skull. Its braincase was so ape-like that it could not house a human-like brain.
Australian Aborigines have a prominent brow ridge, a fact that helped lead Thomas Huxley to argue that Neanderthals were indeed human.
"I feel myself constrained to believe that the thoughts and desires which once dwelt within it never soared beyond those of a brute," King wrote.
From all this evidence, King concluded that the Neanderthal Man was not simply an ancient European, as Schaafhausen had thought. It was a separate species. He even gave that species a name: Homo neanderthalensis.
King was certainly right that Neanderthals were distinct from living humans. Subsequent generations of fossil-hunters have found remains of Neanderthals from Spain to Israel to Russia. The youngest Neanderthal fossils date to 28,000 years ago. The oldest ones date back over 200,000 years. Like the original Neanderthal Man, they were stocky, with a heavy brow ridge and other singular traits. We can't know exactly what thoughts and desires soared in their heads, but they certainly left behind some telling clues—carefully engineered spear blades and stone knives painted shells that might have been used as jewelry. Neanderthals endured the comings and goings of ice ages in Europe and Asia, hunting for reindeer, rhinoceroses, and other big game.
As the fossils have emerged, paleoanthropologists have revisited the question of whether Neanderthals are part of our own species—call them Homo sapiens neanderthalensis—or a separate Homo neanderthalensis. Some researchers argued that Neanderthals belonged to a single species of humans stretching across the Old World, one that evolved over the past million years from small-brained hominids into our big-brained form.
Europeans and Asians carry a small portion of DNA inherited from Neanderthals.
But some researchers challenged this view. They pointed out that for thousands of years, Europe was home to the burly Neanderthals as well as slender humans. Neanderthals didn't give rise to living Europeans, these scientists argued they were replaced by immigrants expanding out of Africa—perhaps even outcompeted into extinction.
Over the past 15 years, Svante Pääbo, a geneticist at the Max Planck Institute of Evolutionary Anthropology, and his colleagues have uncovered an entirely new source of evidence about the nature of Neanderthals: their DNA. Starting with those fossils from the Neander Valley, they extracted bits of genetic material that had survived tens of thousands of years. Eventually, they were able to assemble the fragments into the entire Neanderthal genome.
Populations of the same species that a river or other barrier divides can become unable to breed successfully with each other. Such an inability never occurred between Neanderthals and humans, who bred successfully at least once.
It's clearly different from the genome of any human alive today, sprinkled with many distinctive mutations. These mutations accumulated in a clock-like way, and by tallying them up, Pääbo and his colleagues estimate that Neanderthals and humans share a common ancestor that lived 800,000 years ago. It's possible that the ancestors of Neanderthals expanded out of Africa then, while our own ancestors stayed behind.
A question of breeding
That's a long time—long enough to reasonably ask if humans and Neanderthals are indeed two separate species. Old species split into new ones when some of their members get isolated from the rest. If a river cuts the range of a species of frog in two, for example, the frogs on one side of the river may only be able to mate with one another. Each population will evolve along its own path. If they are isolated long enough, they will have trouble interbreeding. They may even be unable to interbreed at all.
From these facts of evolution, the biologist Ernst Mayr developed what came to be known as the Biological Species Concept in the 1940s—namely, a species is made up of members of populations that actually or potentially interbreed in nature. Experiments on living animals have shown that barriers to this interbreeding can arise in tens of thousands, or even just thousands, of years.
Once the Neanderthal lineage left Africa 800,000 years ago, did humans and Neanderthals have enough time to become unable to interbreed? Pääbo's research provides an answer: no.
Does the late Ernst Mayr's notion of what constitutes a species, which held sway for many decades, need to be scrapped or substantially revised? Many biologists believe so.
Europeans and Asians carry with them a small portion of DNA inherited from Neanderthals—while Africans do not. The best explanation for our mixed genomes is that after humans expanded out of Africa, they encountered Neanderthals and interbred. Comparing the different Neanderthal-derived genes in different people, Pääbo and his colleagues estimate that this encounter occurred around 40,000 years ago. The tiny amount of Neanderthal DNA has been interpreted by some scientists as evidence that Neanderthals rarely mated with humans—perhaps just once, in fact. But as scientists sequence more genomes from more human populations, they're exploring the possibility that our ancestors mated with Neanderthals several different times.
A matter of survival
The presence of DNA from Neanderthals in human genomes is compelling evidence that humans and Neanderthals could mate and produce fertile offspring. If we stick to the Biological Species Concept, then we are a single species, as Schaafhausen originally thought. But some scientists reject this argument. They think that Mayr's Biological Species Concept has worn out its usefulness.
Homo neanderthalensis and Homo sapiens endured—at least until the Neanderthals became extinct.
With the advent of gene sequencing, scientists have found that many animal species regularly interbreed. It's easy for any safari tourist to tell the difference between olive baboons and yellow baboons that live in Kenya, for example. And yet the two species regularly produce hybrids in the places where their species overlap, and they've been doing it for a long time.
What will it take for experts to agree on whether Neanderthals (foreground) and modern humans are one and the same species?
So why haven't the two baboon species merged into a single hybrid olive-yellow species? The baboons produced by interbreeding may not survive as well as purebred ones. They produce fewer offspring of their own, and so the genes from one species don't spread easily in the other. Thus, despite interbreeding—breaking Ernst Mayr's rule, in other words—the olive and yellow baboons endure as separate species.
Perhaps humans and Neanderthals were the same: They only interbred rarely, and when they did, the hybrid children couldn't fuse the two kinds of humans together. That may be why human and Neanderthal fossils remained so different.
William King would probably have been horrified at the notion of human beings having sex with Neanderthal "brutes." But despite this intermingling, Homo neanderthalensis and Homo sapiens endured—at least until the Neanderthals became extinct, and we survived.
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DNA reveals Neanderthal extinction clues
DNA analysis suggests most Neanderthals in western Europe died out as early as 50,000 years ago - thousands of years before our own species appeared.
A small group of Neanderthals then recolonised parts of Europe, surviving for 10,000 years before vanishing.
An international team of researchers studied the variation, or diversity, in mitochondrial DNA extracted from the bones of 13 Neanderthals.
This type of genetic information is passed down on the maternal line because cells contain multiple copies of the mitochondrial genome, this DNA is easier to extract from ancient remains than the DNA found in the nuclei of cells.
The fossil specimens came from Europe and Asia and span a time period ranging from 100,000 years ago to about 35,000 years ago.
The scientists found that west European fossils with ages older than 48,000 years, along with Neanderthal specimens from Asia, showed considerable genetic variation.
But specimens from western Europe younger than 48,000 years showed much less genetic diversity (variation in the older remains and the Asian Neanderthals was six-fold greater than in the western examples).
In their scientific paper, the scientists propose that some event - possibly changes in the climate - caused Neanderthal populations in the West to crash around 50,000 years ago. But populations may have survived in warmer southern refuges, allowing the later re-expansion.
Low genetic variation can make a species less resilient to changes in its environment, and place it at increased risk of extinction.
"The fact that Neanderthals in Europe were nearly extinct, but then recovered, and that all this took place long before they came into contact with modern humans, came as a complete surprise," said lead author Love Dalen, from the Swedish Museum of Natural History in Stockholm.
"This indicates that the Neanderthals may have been more sensitive to the dramatic climate changes that took place in the last Ice Age than was previously thought."
Neanderthals were close evolutionary cousins of modern humans, and once inhabited Europe, the Middle East and Central Asia. The reasons behind their demise remain the subject of debate.
The appearance of modern humans in Europe around the time of the Neanderthal extinction offers circumstantial evidence thatHomo sapiensplayed a role. But changes in the climate and other factors may have been important contributors.
"The amount of genetic variation in geologically older Neanderthals as well as in Asian Neandertals was just as great as in modern humans as a species," said co-author Anders Gotherstrom, from Uppsala University.
"The variation among later European Neanderthals was not even as high as that of modern humans in Iceland."
The researchers note that the loss of genetic diversity in west European Neanderthals coincided with a climatic episode known as Marine Isotope Stage Three, which was characterised by several brief periods of freezing temperatures.
These cold periods are thought to have been caused by a disturbance of oceanic currents in the North Atlantic, and it is possible that they had a particularly strong impact on the environment in western Europe, note the researchers.
Over the last few decades, research has shown that Neanderthals were undeserving of their brutish reputation.
Researchers recently announced that paintings of seals found in caves at Nerja, southern Spain, might date to 42,000 years - potentially making them the only known art created by Neanderthals. However, this interpretation remains controversial.
Why did Neanderthals become extinct?
You've probably heard the word "Neanderthal" used to insult someone, typically a person acting boorishly or one with a prominent brow ridge. New evidence shows that calling someone a Neanderthal might not be too far from the truth. Neanderthals became extinct earlier than previously thought, but before going extinct, they mated with modern humans' ancestors — the same ones who aided in their extinction.
Neanderthals are an early species of human that lived primarily in Europe and southwest Asia from about 130,000 years ago until their extinction approximately 40,000 years ago. The first Neanderthal bones were found in the Neander River Valley in Germany in 1856, and at the time people thought they were the bones of strange modern humans. Neanderthals were generally more massive but shorter than modern humans. They also had a more prominent brow ridge and sloping forehead [Source: O'Neil].
Since that first discovery, Neanderthal bones have been found across Europe and Asia, from Spain to Russia to Iraq. So what happened to this early species that seems to have been all over the map? It's a question that has plagued scientists for years, but new testing has revealed information that may help explain the Neanderthals' demise.
It appears that we — or at least our ancestors — were at least partially responsible for their extinction. About 45,000 years ago, Neanderthal numbers were dwindling. They had become isolated, living in patchy groups across Europe by the time modern humans (Homo sapiens) were making inroads. The two groups would have competed for food, for shelter, for everything they needed to live -- but Homo sapiens was more technologically advanced. It is also thought that a volcanic eruption in Italy and a cooling climate event about 40,000 years ago delivered the last blow to a species that was already on the way out [source: Vergano].
But before Neanderthals left, some mated with modern humans. Traces of Neanderthal DNA show up in humans to this day.
Model suggests Neanderthal extinction occurred due to human cultural superiority
(Phys.org)—A trio of researchers, two with Stanford University in the U.S. and the third with Meiji University in Japan has created a model that showed that it might be possible that the Neanderthal extinction that occurred in the years after early humans arrived in Europe, was due to the cultural superiority of humans. In their paper published in Proceedings of the National Academy of Sciences, William Gilpin, Marcus Feldman and Kenichi Aoki describe the factors they used to create their model and why they believe it was possible that cultural differences might have been enough to drive the Neanderthal to extinction.
Prior research has shown that populations of Neanderthal were living unfettered in Europe for hundreds of thousands of years, but then, approximately 45 thousand years ago, modern humans arrived in the area after migrating out of Africa—five thousand years later, the Neanderthal were gone. Scientists have offered a variety of ideas regarding what happened—modern humans carried with them diseases that were deadly to Neanderthal, our early ancestors simply killed all the Neanderthals, or Neanderthals were not able to adapt to a changing climate, are the leading explanations that have been offered. In this new effort, the researchers report that a model they built suggests it was possible that Neanderthals went extinct because human cultural advantages were so great that it made survival for the less culturally advanced group impossible.
The researchers used a computer model that had already been built by others to mimic interspecies competition—they added elements that allowed for taking into consideration cultural and technical abilities. The result, they claim, is evidence that a culture that was more culturally advanced could displace one that was less so—even if the less culturally advanced group was initially much larger. The model also showed that such cultural advantages could lead to a feed-back loop—the more advanced one group became the more dominant they became, and the more dominant they became the more their cultural advantage grew. The researchers suggest that cultural advancement goes hand-in-hand with technological innovation which would have allowed early humans to outcompete Neanderthal for natural resources.
What is not clear is why the Neanderthal would not have simply copied the advanced culture or technology developed by early humans once it became clear there was an advantage.
Archaeologists argue that the replacement of Neanderthals by modern humans was driven by interspecific competition due to a difference in culture level. To assess the cogency of this argument, we construct and analyze an interspecific cultural competition model based on the Lotka−Volterra model, which is widely used in ecology, but which incorporates the culture level of a species as a variable interacting with population size. We investigate the conditions under which a difference in culture level between cognitively equivalent species, or alternatively a difference in underlying learning ability, may produce competitive exclusion of a comparatively (although not absolutely) large local Neanderthal population by an initially smaller modern human population. We find, in particular, that this competitive exclusion is more likely to occur when population growth occurs on a shorter timescale than cultural change, or when the competition coefficients of the Lotka−Volterra model depend on the difference in the culture levels of the interacting species.
Sex With Humans Made Neanderthals Extinct?
The two species mated till the Neanderthal lineage melted into ours, study hints.
Neanderthals may have been victims of love, or at least of interspecies breeding with modern humans, according to a new study.
As the heavy-browed species ventured farther and farther to cope with climate change, they increasingly mated with our own species, giving rise to mixed-species humans, researchers suggest.
Over generations of genetic mixing, the Neanderthal genome would have dissolved, absorbed into the Homo sapiens population, which was much larger. (Get the basics on genetics.)
"If you increase the mobility of the groups in the places where they live, you end up increasing the gene flow between the two different populations, until eventually one population disappears as a clearly defined group," said study co-author C. Michael Barton, an archaeologst at Arizona State University's School of Human Evolution and Social Change.
Doing What Comes Naturally
Some theories suggest Neanderthals disappeared about 30,000 years ago because the species wasn't able to adapt to a cooling world as well as Homo sapiens. (See a prehistoric time line.)
Barton tells a different tale, suggesting that Neanderthals reacted to the onset of the Ice Age the same ways modern humans did, by ranging farther for food and other resources.
"As glaciation increased, there was likely less diversity in land use, so Neanderthals and modern humans alike focused on a particular survival strategy that we still see today at high latitudes," Barton said.
"They establish a home base and send out foraging parties to bring back resources. People move farther and have more opportunity to come into contact with other groups at greater distances. The archaeological record suggests that this became more and more common in Eurasia as we move toward full glaciation."
More frequent contact led to more frequent mating, the theory goes, as the two groups were forced to share the same dwindling resources.
"Other things might have happened," Barton said. "But in science we try to find the simplest explanation for things. This theory doesn't include massive migrations or invasions—just people doing what they normally do."
To estimate the effects of the assumed uptick in interspecies mating, Barton's team conducted a computational modeling study that spanned 1,500 Neanderthal generations.
In the end, the model results supported the not entirely new idea that Neanderthals were "genetically swamped" by modern humans.
"Extinction by Hybridization"
Though it's a relative underdog among Neanderthal-demise theories, genetic swamping is a well-known extinction cause among plant and animal species.
A smallish group of native, localized trout, for example, may lose their genetic identity after a large influx of a different species with which the native fish are able to breed.
"When endemic populations are specialized, and for some reason there is a change in their interaction with adjacent populations, and that interaction level goes up, they tend to go extinct—especially if one population is much smaller than the other," Barton explained.
"In conservation biology this is called extinction by hybridization."
Paleoanthropologist Bence Viola said other models have produced different results, and some studies have concluded that relatively little interbreeding occurred.
But Viola, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, is intrigued by Barton's research.
"From an archaeological and anthropological perspective, this sounds interesting and closer to what I believe—that you can have a lot of interbreeding," Viola said.
"Normally the first groups who [encounter] a new population are men, hunting parties perhaps. And men, being they way they are—if they meet women from another population, there is bound to be interbreeding."
Barton believes interbreeding caused other distinct human and human-ancestor groups to fade away.
"But their genes didn't disappear," he added. "And their culture probably didn't disappear either but was blended into a larger population of hunter-gatherers."
The Max Planck Institute's Viola believes interbreeding was a cause—but not the cause.
"Neanderthals disappeared around 30,000 years ago, and that was a period when the climate turned colder, and that likely made it physically harder for them to survive," Viola said.
"They also may have been exposed to some type of disease that modern humans brought from Africa and for which they had no immunity.
"Of course these are all things that are very hard to study archaeologically," Viola added. "So these models are a great tool for investigating ideas."
The Neanderthal-interbreeding study, co-authored by researchers at Arizona State University and the University of Colorado Denver, will be published in the December issue of the journal Human Ecology.
What Really Caused Neanderthals to Go Extinct? New Study Has Shocking Answer
It is one of the great unsolved mysteries of anthropology. What killed off the Neanderthals, and why did Homo sapiens thrive even as Neanderthals withered to extinction? Was it some sort of plague specific only to Neanderthals? Was there some sort of cataclysmic event in their homelands of Eurasia that lead to their disappearance?
A new study from a team of physical anthropologists and head & neck anatomists suggests a less dramatic but equally deadly cause.
Published online by the journal, The Anatomical Record, the study, “Reconstructing the Neanderthal Eustachian Tube: New Insights on Disease Susceptibility, Fitness Cost, and Extinction” suggests that the real culprit in the demise of the Neanderthals was not some exotic pathogen.
Instead, the authors believe the path to extinction may well have been the most common and innocuous of childhood illnesses — and the bane of every parent of young children — chronic ear infections.
“It’s not just the threat of dying of an infection. If you are constantly ill, you would not be as fit and effective in competing with your Homo sapien cousins for food and other resources. In a world of survival of the fittest, it is no wonder that modern man, not Neanderthal, prevailed.” — Professor Samuel Márquez, Ph.D.
“It may sound far-fetched, but when we, for the first time, reconstructed the Eustachian tubes of Neanderthals, we discovered that they are remarkably similar to those of human infants,” said coinvestigator and Downstate Health Sciences University Associate Professor Samuel Márquez, Ph.D., “Middle ear infections are nearly ubiquitous among infants because the flat angle of an infant’s Eustachian tubes is prone to retain the otitis media bacteria that cause these infections — the same flat angle we found in Neanderthals.”
In this age of antibiotics, these infections are easy to treat and relatively benign for human babies. Additionally, around age 5, the Eustachian tubes in human children lengthen and the angle becomes more acute, allowing the ear to drain, all but eliminating these recurring infections beyond early childhood.
But unlike modern humans, the structure of the Eustachian tubes in Neanderthals do not change with age — which means these ear infections and their complications, including respiratory infections, hearing loss, pneumonia, and worse, would not only become chronic, but a lifelong threat to overall health and survival.
“Here is yet another intriguing twist on the ever-evolving Neanderthal story, this time involving a part of the body that researchers had almost entirely neglected. It adds to our gradually emerging picture of the Neanderthals as very close relatives who nonetheless differed in crucial respects from modern man.” — Ian Tattersall, Ph.D.
“It’s not just the threat of dying of an infection,” said Dr. Márquez. “If you are constantly ill, you would not be as fit and effective in competing with your Homo sapien cousins for food and other resources. In a world of survival of the fittest, it is no wonder that modern man, not Neanderthal, prevailed.”
“The strength of the study lies in reconstructing the cartilaginous Eustachian tube,” said Richard Rosenfeld, MD, MPH, MBA, Distinguished Professor and Chairman of Otolaryngology at SUNY Downstate and a world-renowned authority on children’s health. “This new and previously unknown understanding of middle ear function in Neanderthal is what allows us to make new inferences regarding the impact on their health and fitness.”
“Here is yet another intriguing twist on the ever-evolving Neanderthal story, this time involving a part of the body that researchers had almost entirely neglected,” said Ian Tattersall, Ph.D., paleoanthropologist and Curator Emeritus of the American Museum of National History. “It adds to our gradually emerging picture of the Neanderthals as very close relatives who nonetheless differed in crucial respects from modern man.”
Reference: “Reconstructing the Neanderthal Eustachian Tube: New Insights on Disease Susceptibility, Fitness Cost, and Extinction” by Anthony Santino Pagano, Samuel Márquez and Jeffrey T. Laitman, 31 August 2019, The Anatomical Record.