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Did Homo Sapiens Really Mate With Neanderthals?
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May 5, 2025
Before the early 2010s, scientists were conflicted on the question of Homo sapiens interbreeding with Neanderthals, but since then, multiple studies have shown the incredible overlap between Neanderthal and human DNA - enough that approximately 1%-4% of modern human DNA traces directly back to Neanderthal ancestry.
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Neanderthals are believed to have coexisted with modern humans for tens of thousands of years
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Before the early 2010s, scientists were conflicted on the question of whether Homo sapiens ever
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interbred with Neanderthals. But since then, multiple studies have shown an incredible overlap
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between Neanderthal and human DNA. In fact, evidence shows that Homo sapiens not only met
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Neanderthals, they also slayed them, ate them, and from time to time, got it on with them
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Today, we're going to take a look at whether Homo sapiens really mated with Neanderthals
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Movies and cartoons tend to make Neanderthals look significantly different from Homo sapiens
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but the truth is, there wasn't much difference between the two groups
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While Neanderthals were slightly stockier and had thicker bones, the two were actually quite
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compatible in other regards. In fact, they were so compatible that according to one study
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on average, up to 4% of an average modern human's genetics can be traced directly to the Neanderthals
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While the Neanderthals may have vanished as a separate species right around 30,000 years ago
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this study provides some solid genetic evidence that they were getting it on with prehistoric
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homo sapiens while they were still around. Homo sapiens and Neanderthals most likely
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mated and fought each other. But otherwise, the two groups might have been nearly indistinguishable
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when they coexisted in Europe and the Middle East. That's because Neanderthal DNA is almost
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identical to human DNA. In fact, Homo sapiens and Neanderthals share 99.7% of their DNA
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That figure makes Neanderthals much closer genetic relatives to modern humans than primates like
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chimps, who share 98.8% of their DNA with humans. The Homo sapiens and Neanderthals also crossbred
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which introduced even more Neanderthal DNA into the modern human genetic pool
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Recent scientific evidence suggests that Homo sapiens and Neanderthals interbred it several
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times and in several places over the millennia. The earliest of these mixings may have occurred
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over 100,000 years ago, when some relatively smaller groups of Homo sapiens first started
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leaving Africa. Homo sapiens are then believed to have started migrating from Africa in significantly
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larger numbers approximately 60,000 to 65,000 years ago. While they spread to the Middle East and Europe
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they inevitably encounter Neanderthals in greater numbers. And while the two groups had their share of conflicts
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no doubt, the genetic findings make it clear that they were also mating by this point
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It is now widely believed that this interbreeding with Neanderthals likely shaped the DNA
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of subsequent generations of Homo sapiens. Homo sapiens got around They migrated all over the world and they sometimes interbred with other hominid species For this reason almost all modern humans
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carry some small amount of the Neanderthal genome. However, there is one group that shows absolutely no evidence
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of interbreeding with Neanderthals, people with solely African ancestry. Yes, because sub-Saharan Africans rarely encountered
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or interacted with Neanderthals, they never had a chance to mingle their respective genomes. As recently as 2010
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scholars believe that interbreeding between Homo sapiens and Neanderthals likely only stretched
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back about 60,000 years or so. That was about the time when Homo sapiens left Africa and slowly
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began to spread throughout the Middle East and Europe. However, that theory created a very
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interesting mystery. Namely, if Neanderthals and Homo sapiens didn't interbreed until 60,000 years
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ago, how did a Neanderthal living in southwest Germany 100,000 years ago have homo sapien
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mitochondrial DNA, or MTDNA? The answer to the mystery was finally discovered in 2017
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when research revealed that a female human in Africa had mated with a Neanderthal male over
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220,000 years ago. This coupling spread MTDNA to an entire lineage of Neanderthals
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who may have met homo sapiens in Europe tens of thousands of years later
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While it might have been fun at the time, interbreeding with Homo sapiens might not have ultimately been the best idea for the Neanderthals
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The Neanderthal Y chromosome was not completely compatible with the Homo sapien Y chromosome
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And as a result, if a Neanderthal male procreated with a Homo sapien female
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the pregnancy would have frequently ended in a miscarriage. Population geneticist Fernando Mendez found the cause of the problem
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when he identified mutations on the Neanderthal Y chromosome that would trigger an immune response from a Homo sapien woman
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If she became pregnant, the woman's immune system would kick in to protect her at the expense of the pregnancy
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In fact, the problem may have been so pronounced that Neanderthals might have actually gone extinct
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after intermixing with Homo sapiens and essentially becoming absorbed into their group
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As Homo sapiens tried to expand from Africa into Neanderthal territory in Europe and Asia
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they might have ignited a struggle between the two groups that would last 100,000 years
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That's a long struggle. In November 2020, evolutionary biologist and paleontologist Nicholas R. Longrich said that although it's tempting to think the two groups might have got
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along, biology and paleontology paint a darker picture. Far from peaceful, Neanderthals were
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likely skilled fighters and dangerous warriors Archaeological evidence indicates that Neanderthals used spears to hunt big game which suggests that they likely also used such weapons to protect themselves
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This is supported by the fact that both Neanderthal and Homo sapien prehistoric remains
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frequently show signs of skull and upper body trauma. Shanidar III, for example, a 40-year-old Neanderthal who lived in Iraq around 50,000 years ago
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was slain after a spear pierced him through the ribcage. Anthropologists demonstrated that the weapon that took Shanidar III's life
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could have been a lightweight projectile spear. A Neanderthal jawbone discovered from a cave in southwestern France
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showed signs of being cut with a stone tool, indicating the Neanderthal child was likely slain and eaten
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Anthropologists speculate that the Neanderthals likely survived for over 100,000 years, despite the Homo sapien conquest, because they had a few practical advantages
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For one, they were far more familiar with the terrain than the Homo sapiens who were just only moving in
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The Neanderthals also had very muscular bodies and large eyes that aided in close combat
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and in dark lighting conditions. Neanderthals also had a surprisingly advanced level
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of technology. This included the stone tools and the abilities to create fire and build cave hearths
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They knew how to use cooking techniques, such as smoking, roasting, and boiling
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and could store food. Neanderthals also possessed the ability to weave, and they are known to have crafted simple clothes
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like blankets and ponchos. They also knew how to use various herbs medicinally
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and they had relatively impressive seafaring skills that were sufficient to carry them
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across the Mediterranean. While it's not entirely clear why the Homo sapiens
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eventually prevailed in the struggle, some researchers believe one reason is that despite the Neanderthals' impressive level
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of technology, the Homo sapiens may simply have developed better weapons and hunting techniques
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So why did Neanderthals go extinct while Homo sapiens flourished? The answer to that question is incredibly complex
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But part of the reason has to do with the incredibly small size of the Neanderthal population
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Between 38,000 and 70,000 years ago, the Neanderthal population in Europe was very small
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and included perhaps as few as 1,500 female Neanderthals of reproductive age
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By the twilight of the Neanderthal era, they were simply outnumbered by Homo sapiens
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According to some anthropologists, while climate change and disease may have played a role in the end
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of the Neanderthals, this population imbalance may have been the biggest problem
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That is, because there were never millions of Neanderthals in the first place, they were much more susceptible
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to an extinction event And that event may have turned out to be the emergence of us the modern humans While Neanderthals and Homo sapiens diverged evolutionarily around 5 years ago
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the two groups weren't that different. Homo sapiens edged out the Neanderthals slightly in
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height, while the Neanderthal boasted bigger and stronger bones. That is, Homo sapiens had the reach
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but Neanderthals had the power. Neanderthals had larger brow ridges and bigger noses
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which were likely adaptations to cold weather environments that helped them warm larger quantities of air
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Another similarity anthropologists commonly refer to is the genitalia. Neanderthal junk probably looked a lot like human junk
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Anthropologist John Hawks explains that most primates have horny papillae, or spines on their penises
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But both humans and Neanderthals were missing the genes for these spines
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Pretty convenient if you're planning to interbreed. So like we said earlier, Homo sapiens
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were notoriously promiscuous. No, seriously, early Homo sapiens were the Casanovas of the
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prehistoric world, and Neanderthals were far from being the only hominids that they interbred with
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New research shows that Homo sapiens also mated with Homo erectus and Homo habilis
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as well as with the Denisovans, who populated much of Asia. In fact, modern people from Oceania
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and East Asia still carry fragments of Denisovan DNA to this very day. Far from being an isolated
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occurrence, researchers now believe that there were probably thousands of interbreeding events
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that happened regularly and on relatively wide scales. Sounds like one heck of a party
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This all worked out pretty great for Homo sapiens in the end. They not only had rich and fulfilling
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sex lives that allowed them to interbreed with other hominid species, but they also ultimately
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outlived their competition. While all this sounds pretty convincing, not quite everyone is buying it
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Some scholars have seriously questioned the recent study showing Neanderthal human interbreeding
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In fact, in a 2012 study, researchers precisely dated Neanderthal bones from southern Spain
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discovering they predated the arrival of Homo sapiens in the area by as much as 10,000 years
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While it's possible Homo sapiens arrived in the area sooner than previously believed
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barring new evidence, it seems unlikely the two ever crossed paths there
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Other scientists have argued that the genetic similarities between Neanderthals and Homo sapiens
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actually trace back to a common ancestor, rather than coming from interbreeding
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While this can't be ruled out, the fact remains that modern humans show up to 4% Neanderthal DNA
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Coupled with the apparent lack of Neanderthal DNA and those of solely African descent
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interbreeding remains the current scientific consensus to explain the genetic similarities
#Genetics