--- title: "People and Neanderthals Lived Together. Here's How We Know." description: "Has anyone ever called you a neanderthal? Well, that's actually not offensive because that person was most likely right. Everyone except for Subsaharan natives has at least some neanderthal DNA mixed in with their own. This is the result of thousands of years of cohabitation and interbreeding between our two species.\n\nIn a very uniquely human egoistic way, for the longest time we saw Neanderthals as savages and brutes that stood in humanity's way of world dominance and posed a threat to our survival. The reality is, however, quite the opposite.\n\nNot only have humans and Neanderthals lived together, but we also influenced one another's genetic code, societal development, and eventually the extinction of one, and biological perseverance of the other species.\n\nNeanderthals are, in a way, still alive — here's why.\n\n## Neanderthals and Humans — Two Separate Lineages\n\nAlthough the exact hominid family tree still can't be agreed upon by anthropologists because there are simply too few fossils to provide us with a specific answer, it's widely believed that *Homo heidelbergensis* was the last common ancestor of Neanderthals and modern day humans.\n\n*Homo heidelbergensis*, named after the German city of Heidelberg, near which a fossil was found in the early 20th century, evolved simultaneously in Africa and Eurasia from *Homo erectus* around 600,000 years ago. Some 200,000 years later, the African group would evolve into *Homo sapiens*, otherwise known as the person you see in the mirror every time you pass by it, and the other group would separate into two and evolve into Neanderthals and Denisovans. Denisovans are, for clarity, a humanoid species very closely related to Neanderthals. In fact, some anthropologists even wanted to classify them as a Neanderthal subspecies, but they were in fact their own species, and alongside Neanderthals, they're our closest cousins.\n\nFor hundreds of thousands of years, humans never bothered to leave Africa. Denisovans were largely living in Asia, with Neanderthals spreading across both Asia and Europe, with Italy, Spain, France, and Germany having the highest fossil finding density. This, however, shouldn't limit our view of them as Neanderthals were fantastic nomads, capable of establishing long-lasting cultures over 3,000 kilometers in less than 2,000 years. This might not sound impressive now because such a distance is nothing more than a flight away for you nowadays, but keep in mind that Neanderthals lived roughly 400,000 to 240,000 years ago. They had to cross an unforgiving wilderness on foot, without access to sophisticated tools or weapons.\n\nAccording to the latest stone tool findings, it's entirely possible that Neanderthals have, in fact, lived for much longer than we think — up to 32,000 years ago — and that they inhabited one of the harshest environments on earth, the Arctic.\n\nAt the same time, Denisovans were establishing communities in modern-day Siberia, Tibet, Taiwan, China, New Guinea, and Australia. Denisovans migrating across the Wallace Line, the natural faunal line between Asia and Australia, is a very recent discovery based on high DNA percentages in modern Australians and Papuans.\n\nAt the same time, we were…doing nothing. The lazy bastards that we are, we've actually spent the majority of our existence as a species not bothering to venture outside of Africa. Of course, some isolated cultures from northeastern Africa migrated to Southern Europe and the Middle East, but not in big enough numbers to leave a trace. The oldest known trace of such a migration is a human skull found in Greece dated to about 210,000 years ago, but this is an exception rather than a rule.\n\nAs a species, we spent close to two-thirds of our 300,000-year existence just moving across Africa, and large-enough migration waves that would establish long-term cultures wouldn't occur until about 100,000 years ago. Then, early humans crossed the Bab-el-Mandeb strait between the Arabian Peninsula and the Horn of Africa while the tide was low and spread across the modern day UAE, Oman, and India.\n\nThe northern route, which crossed the Sinai Peninsula, was also used, and by using those two routes, humans later migrated to Europe and Asia, while those who entered Central Asia later migrated to the north, then crossed the Beringia land bridge, which existed at the time, and spread across modern day North and South America.\n\nHere is the very important part, though. Throughout the vast majority of our migration across Europe and Asia, we constantly came across Neanderthals and Denisovans. In fact, they only went extinct roughly 40,000 years ago, which means that, as a species, we actually spent more time with them than without them, and since we bumped into them so many times, cohabitation and interbreeding was unavoidable, and we today know for certain that our cultures lived together.\n\n## Neanderthal and Human Cohabitation\n\nThe first humans reached the heart of Europe, modern-day Germany, around 45,000 years ago. Five thousand years later, Neanderthals were completely extinct aside from a few pockets of the surviving culture in Iberia. Throughout that short time period, however, some humans shared territory with the Neanderthals instead of competing for it.\n\nThe Tishemet Cave in modern-day Israel is one of the best examples of Neanderthal and human cohabitation. According to the research team, several groups of humanoids, including humans, Neanderthals, and pre-Neanderthals, maintained ongoing contact for many years. This resulted in the exchange of tools, hunting practices, various rituals, and, of course, DNA.\n\nIt's highly likely that Tishemet Cave was used as a burial site by both humans and Neanderthals. This is one of the oldest burial places in the world, dating at some 110,000 years old, which is right around the time when the first humans started migrating from Africa to Eurasia, and their path would take them to the cave. Objects such as stone tools, animal bones, and pieces of ochre were found at the site, alongside human and neanderthal remains of roughly the same age. According to Professor Yossi Zaidner, who's in charge of the dig, the Cave was a melting pot for different humanoid populations. There, they regularly came into contact with one another and influenced one another's burial practices.\n\nScientists also believe that Neanderthals and humans shared the modern-day Cave River nature reserve in Israel. There's evidence of interbreeding and technology sharing with stone axes and sharp arrowheads found in both human and Neanderthal caves.\n\nMore evidence proving good neighbourly relations between humans and Neanderthals comes from Germany. Scientists from Berkeley analyzed DNA from numerous bone fragments found at Ranis, and discovered that they are most definitely human. However, by dating them, they found that the bones are at least 45,000 years old or quite possibly 2,500 older. This would not only make those humans some of the first in Europe, but it would also put that particular human culture at the right place and at the precisely right time to share their immediate area with Neanderthals.\n\nA similar thing happened in France about 50,000 years ago. Somewhere on the slopes of the Prealps in southern France, the Mandarin Cave was most likely shared by humans and Neanderthals. By dating the remains, the anthropologists deduced that humans inhabited the cave precisely 54,000 years ago. This means that they were most likely an oddly successful nomad culture that got further west than any human by that point, but this was by no means common and they were an outlier more than anything. Interestingly, local Neanderthals have used the cave both before and after that human culture. According to the article published in *The Conversation*:\n\n> \"When Neanderthals and modern humans made fires in the site, the smoke would leave a layer of soot on those surfaces. Then the following season a thin layer of calcium carbonate called speleothem would cover it over. This cycle was repeated over and over. A decade of work…has shown that these patterns can be read like tree rings to tell us with what frequency and duration the groups visited the site, demonstrating that human groups came to Mandrin some 500 times over 80,000 years.\"\n\nBy reading the layers of soot and calcium carbonate, the scientists were able to determine that no more than a year had passed between the last time the Neanderthals used the Cave and the time the first humans moved in. The humans occupied the cave for about 40 years and likely shared the immediate territory with Neanderthals, and once they abandoned the cave, the Neanderthals moved back in and remained there until extinction.\n\nThere is also cultural evidence suggesting that Neanderthals were influenced by early humans. Samples taken from some Neanderthal sites include very human-specific artifacts that were never made by Neanderthals, which would suggest that some Neanderthal culture adopted our own habits and copied our technologies.\n\nThe most obvious proof of us sharing territory with Neanderthals is, however, found in biology. The University of Adelaide ran a DNA study of Neanderthal dental plaque found at the El Sidron cave in Spain and found evidence of a bacteria that causes gum disease and dental caries. The only issue is the fact that the disease should only be present in modern humans and that the remains in question are 180,000 years old. So, how did a 180,000 year-old Neanderthal get a human-specific microbe in his or her mouth? The most apparent answer is that the Spanish Neanderthals grouped with our forager ancestors in Africa. The composition of the oral bacterial population closely correlates to the amount of meat in someone's diet, something that applies to both humans and Neanderthals, and the composition of the microbes from the sample in the north of Spain is extremely similar to ancient humanoid microbe compositions. The other explanation is that the Neanderthal in question exchanged saliva with a human, and that's what takes us to the strongest argument proving that we lived with Neanderthals.\n\nThere's simply too much evidence of interspecies breeding to ignore.\n\n## Interbreeding and Its Results\n\nWhen the first larger migratory waves of humans arrived in Europe, the Neanderthals were most definitely the superior species. They were pound for pound stronger than modern humans, they were faster, they knew the lay of the land, and since they had already been living in Europe for at least 200,000 years by the time we arrived, they were better adapted for the cold weather. Europe back then was much colder than it is today and very few cultures dared migrate more north than Germany because of the intense cold.\n\nSuffice it to say that we needed a little bit of that Neanderthal DNA if we planned on surviving in Europe.\n\nAccording to Ludovic Slimak, an archeologist with the Center for Anthropology and Genomics of Tolouse, when two populations are physically close, but still separated by traditions and language, they are going to exchange women. This is, obviously, extremely sexist, primitive, and inhumane by modern standards, but it is simply the way early human societies functioned.\n\nThe purpose of exchanging women is the creation of a larger, universal clan, which ultimately makes survival easier for both groups. Although the groups won't necessarily live together, by exchanging members, they're not only exchanging DNA, but knowledge as well. This is a universal phenomenon common with various human clans across history, not just something we can observe with Neanderthals and humans.\n\nNo single species had the upper hand in the interbreeding. According to the analysis of Y chromosomes of remains found in the Altai Mountains in Russia, Neanderthal Y chromosomes are more similar to the chromosomes of modern humans than the chromosomes of Denisovans, which is odd as Neanderthals and Denisovans are more closely related to one another than either group is to us. Anthropologists still don't know why that is so.\n\nThe prehistoric 50 Shades of Grey was a two-lane road, however, as some human mitochondrial DNA was found in Neanderthal remains. We know that in humans, mitochondria, which is the part of your cells that turns sugar into usable energy, is exclusively passed down from a mother to her children. If a Neanderthal has human mitochondrial DNA, it proves that they had a human mother.\n\nAside from sharing women, we also shared sexually transmitted diseases with Neanderthals. Professor Ville Pimenoff of the University of Oulu realized this by accident when he was studying the human papillomavirus. All humans have a number of papillomavirus infections throughout our lives, and most of them are asymptomatic. However, the Type 16 HPV is the well-known strain responsible for anogenital cancers.\n\nThis HPV type is further categorized into five subtypes. AFR-1 and AFR-2 types mostly occur in Subsaharan Africa, while the EUR type occurs in Europe, and guess what? The type dispersion almost perfectly matches the distribution of Neanderthal DNA around the world.\n\nPimenoff calculated that the EUR type of HPV16 first emerged around 60 to 120 thousand years ago, which is right around the time when archaic humans started massively moving into Europe, and it's likely that the strain switched hosts from Neanderthal to *Homo sapiens*. The only way of doing that is by copulating. It's likely that the perpetrators were some of the earliest humans in Europe and Asia who came in contact with Neanderthals in modern-day Iran and Turkey, long before they explored the hearts of the continents.\n\nWhat supports this theory further is the fact that the virus is so cancerous in humans. If you think about it, we only came in contact with the EUR type of HPV16 very recently in our evolutionary history and our immune systems simply haven't yet evolved to fight it properly. So…Neanderthals kind of gave us cancer, but we gave them herpes in return so the interspecies STD ledger kind of balances itself out.\n\nEven though neither we nor the Neanderthals were faithful to our own species, we were faithful to our partners. Ancient humans and Neanderthals were both largely monogamous, and we know this for a fact thanks to…ancient penises. Yes, that's right, the anatomy of the male genitalia is actually key to understanding monogamy in mammals.\n\nBased on the Neanderthal genetic code research, we know that just like human ones, their penises were smooth. The same cannot be said for the majority of the animal kingdom, but with Neanderthals, it's a sure sign that the females made babies with very few partners, usually just a single one.\n\nBefore I explain it, you should be warned that you're about to have a fantastically nasty picture painted in your head. So, the penises of most male animals — thank God, not humans — have something called penile spines covering them completely. These spines are essentially tiny barbs that are supposed to clear out the sperm of competing males. Why did evolution come up with this, you wonder?\n\nIn the wild, when a female animal is ready to make babies, it will usually copulate with more than a single partner, and much of that copulation is non-consensual, by the way — just saying that in case this hasn't ruined wildlife enough for you. It is the goal of every single species to continue the life of that species, and this is something that applies to humans as well, it's ingrained in everyone's DNA, we can't help it. On an individual level, it's every animal's instinct to spread its very own DNA, which is why males compete for the females in the wild — they see them as nothing more than incubators for their offspring.\n\nSo, in the wild, it's completely natural for a single female to copulate with several males in a very short time period, and these penile barbs are supposed to remove the previous male's sperm. The barbs have a texture very similar to a cat's tongue, so if you've ever been licked by a cat, you know that you should be grateful for not being born as one, and you now finally understand why they're moaning in pain every time they mate.\n\nThe main point of this penile barb monologue is that we don't have them, and Neanderthals didn't have them either, which means exactly one thing — there is and was not enough genetic competition for our own and Neanderthal evolution to bother with developing barbs.\n\nNeanderthal communities usually composed of brothers and cousins and their own female partners and children — there was very little room for promiscuity. If a Neanderthal clan exchanged one of their own female members for a human female, that human female would usually spend the rest of her life with her Neanderthal partner.\n\nThe result of such an interspecies marriage wasn't often successful, though. According to years of research, the children of human males and Neanderthal females could survive, but the adverse rarely happened. We know this because most humans nowadays have at least some Neanderthal DNA — we'll get to the specifics later — but very few Neanderthal remains with human DNA were ever found.\n\nIt's believed that the children of male Neanderthals and female humans were most likely sterile. We still don't know why that is, but we might find the answer if we look at other mammalian species. What do you get when you forcibly mate a male lion and a female tiger? A liger. That's not a joke, it's an actual lion-tiger hybrid and it's one of the largest cat species in the world. Calling it a species, however, is biologically incorrect because male ligers are completely sterile, and being capable of reproducing is the most important identifying feature of a species.\n\nMules are similar. They're the offspring of a male donkey and a female horse and they are almost always sterile, although a few medical miracles have been documented.\n\nThis is in accordance with Haldane's rule, which is one of the most important laws of hybrid biology. That rule states that in species hybridization, if one sex has to be sterile, it will always be the one with different sex chromosomes. This means that male human-Neanderthal hybrids were most likely the sterile ones, while female hybrids could probably successfully mate with other Neanderthals or humans. This explains why human mitochondrial DNA was found in Neanderthal remains.\n\nThe Neanderthal Y chromosome is one of the reasons why human women could rarely successfully mate with Neanderthal males. According to *Live Science*, the Y chromosome created conditions that might have led to miscarriages. After analyzing the Y chromosome of a Neanderthal male found in Spain, researchers found three mutations that could trigger immune responses from human women during pregnancy, which could lead to a miscarriage. Human males only have one of those three mutations. To simplify it — male Neanderthals were simply incompatible with human women, and just going through the pregnancy and giving birth was, from a medical perspective, a success.\n\nThe human-Neanderthal mating rate would quickly die down, though. The oldest human remains found in Neanderthal-rich areas and dated to the right time period have the longest stretches of Neanderthal DNA. However, if we fast forward just by a few thousand years, Neanderthal segments in human DNA become much shorter. The two most reasonable explanations are that people with more Neanderthal DNA were simply less fertile, or that breeding with Neanderthals resulted in unwanted features and mutations that we wanted to eradicate, so we avoided mating with human-Neanderthal offspring.\n\nWe have very little information on what human-Neanderthal hybrids looked like. Even though we have some Neanderthal DNA now, we lack pronounced Neanderthal features. The only two skeletons that give us any idea what a Neanderthal-human person could look like are those of children. A skeleton of a boy, dated to about 24,500 years ago, found near Fatima in Portugal had a stocky torso and short legs, which are characteristic of Neanderthals, but a normal, human chin, jaw, and arm bones. An even older set of remains, one dated to about 40,000 years ago, was found in Romania. The skull is rich with both human and Neanderthal traits, particularly the extremely large molars and a flat head. This individual was between 6 and 9% Neanderthal, and that makes him the person with the highest percentage of Neanderthal DNA ever found, at least so far.\n\nSpeaking of features, breeding with Neanderthals has most definitely affected our genetics.\n\nTaller noses, for example, likely come from Neanderthals. Neanderthals developed tall noses as a way of dealing with the intense cold in Europe, and through mating with them, we inherited one specific gene that determines nasal height. The noses of modern humans are designed to regulate the temperature and humidity of colder air, while our ancestors' noses were smaller because the air in Africa was warmer.\n\nGenes affecting keratin have been introgressed from Neanderthals in East Asians and Europeans, effectively determining the way our hair looks. Baldness is still, interestingly, an inherently human thing. The skin pigmentation gene was also affected by Neanderthal genetics.\n\nOther genes, such as those involved with the function of sugar metabolism, muscle contraction, enamel thickness, brain size, and body fat distribution, have all been influenced by Neanderthal genes.\n\nThere are also three Neanderthal genes that result in great pain sensitivity in humans who carry all three variants, while we also share the FOXP2 gene, which, when mutated, leads to speech problems, as well as problems with oral and facial control.\n\nOur immune systems were by far the most affected by Neanderthal DNA. By breeding with Neanderthals, we acquired the genetic resistance to certain European diseases that we had never encountered before. This gave the offspring a better chance at survival, but it also resulted in backfiring. Some autoimmune diseases are the direct consequence of breeding with Neanderthals. Graves' disease, for example, which causes the thyroid to produce hormones in excess, can be a result of Neanderthal genes. Even COVID-19 has been affected by this. In 2020, researchers found that the Neanderthal genome plays a huge part as a genetic risk factor for severe COVID. A lot of people who died from COVID were affected by this. Similarly, one of the genes responsible for Duputryen's disease, an illness that causes the thickening and shortening of finger tissue, comes from Neanderthals.\n\nSome Neanderthal genes in humans were originally very important but have outlived their usefulness. The clotting gene is one of them. We inherited it from Neanderthals and it was useful when we hunted every day as it allowed the blood to quickly clot and prevent bleeding from small wounds. However, since we're not exactly chasing after reindeer in the woods every day nowadays, this same gene is now useless and even dangerous. It can cause harmful clots to form in the later stages of life. Another Neanderthal gene can cause neurological disorders when the natural sleep cycle is disturbed — this can actually cause depression. It's likely that Neanderthals rarely experienced this because they actually had much better sleeping habits than we do nowadays, but the gene was there.\n\nAnd to end this Neanderthal gene tirade, we'll say that by far the most ridiculous gene is the group of genes regulating everyone's circadian rhythm. So, if you're not a morning person, you might have your Neanderthal ancestor to blame.\n\nWe inherited pretty similar genes from the Denisovans, with the addition of a few adaptations for survival at high altitudes, and these genetic adaptations are the ultimate proof that we not only spent thousands of years living alongside Neanderthals and Denisovans, but that we bred with them.\n\nToday, Melanesians and Aboriginal Australians have, on average, between 4 and 6% Denisovan DNA, with the Ayta Magbukon people having the highest level of Denisovan ancestry in the world, ranging from 30 to 40%.\n\nWhen it comes to Neanderthals, Europeans carry about 1.5 to 2.5% of Neanderthal DNA, while East Asians have more — on average, mind you — with 2.5% being the average. Non-Subsaharan Africans have about 2% Neanderthal DNA, while Subsaharan Africans are the only people in the world with no Neanderthal DNA admixture. Native Americans have between 1.5 and 2% Neanderthal DNA on average with about 0.2% Denisovan DNA.\n\nAfter taking a short trip down ethnicity lane, two thoughts come to mind. First of all, considering that humans are already pretty racist now, can you even begin to imagine how incredibly racist we would be if we had to share the planet with another humanoid species? Just makes you wonder — if some people are losing their minds over skin color, how bad would they get if they met someone whose features are humanlike, but not human.\n\nSecondly, we are proof that we lived with Neanderthals, and even though they have gone extinct, they live through us in a way, and, in fact, we are one of the primary reasons they're not here anymore.\n\n## Our Cohabitation Led To the Neanderthals' Demise\n\nThe \"Why have the Neanderthals gone extinct?\" question is one that anthropologists have been trying to answer ever since the species was described for the very first time. Although there is no definitive answer to the question yet, and it's reasonable to assume that there will never be one, it's widely believed that the Neanderthal extinction is the result of a combination of factors, almost all of which had something to do with us, the human race.\n\nIt should be pointed out, just for the sake of chronological clarity, that the Neanderthals went extinct around 40,000 years ago, although a few isolated cultures remained alive for a few thousand years. Those cultures were, however, nowhere near enough to repopulate the entire species.\n\nOne of the primary ways we contributed to their extinction is by spreading pathogens. Similarly to how we weren't equipped to deal with Europe-based parasites and pathogens when we first arrived on the continent, the Neanderthals weren't equipped to deal with the pathogens we brought from Africa.\n\nSince we lived so close together and interbred so many times, we transferred Africa-based pathogens to them that killed them by the thousands. This had a catastrophic effect because the Neanderthal population was never that large, with anthropologists saying it ranged from 3,000 to 12,000 adults. They had a naturally lower fertility rate and had fewer children than humans who, as now know, went at it like rabbits. The Cro-Magnons, which are the first ever humans to come into contact with the Neanderthals, outnumbered their local adversaries ten to one. This means that the Neanderthals were quite literally surrounded by a bunch of pathogen fountains that were taking over territory and spreading like wildfire.\n\nThe natural question here is if Neanderthal populations were decimated by our illnesses, why didn't the same thing happen to us? It did, actually, to a degree, but by the time we first arrived in Eurasia, we were much better equipped to handle new illnesses thanks to something called the 'African advantage'. The disease load of the African tropics was much higher and humans evolved a stronger and overall better immune system in comparison to Neanderthals. Our immune system was also better at adapting, and it did that fairly quickly, and we also plugged the holes in it by breeding with Neanderthals and getting genes that would help our immune systems deal with Eurasia-specific pathogens.\n\nNeanderthal immune systems were specialized for local pathogens, but they faced fewer and less severe illnesses, which made them comparatively weak and slow, which partly led to their demise. A very similar thing happened to Native Americans when they first came into contact with Europeans.\n\nAnother way we contributed to the Neanderthals' extinction is by simply taking over their territory. Although we didn't necessarily engage in a war, and we even interbred with them, it's in our nature to expand territory in order to secure our survival, which is exactly what happened here.\n\nWe lived in larger groups which were better connected to one another and allowed trading, as well as the spread of technology. Neanderthals lived in smaller, isolated tribes — their tools were sophisticated, yes, but there were very few technological improvements over time. We were most definitely beating them in the technological race.\n\nThey were also less efficient in acquiring resources as some Neanderthal tribes didn't divide labour based on sex. Females were often hunting with males, and this was during an era when you had to run for miles on end to tire out a deer or a doe and have enough strength to drag it back home, so it's safe to say things could have been done more efficiently.\n\nSpeaking of running, this was a massive disadvantage for the Neanderthals as their bodies were built for fighting and wrestling, not for half-marathons. Humans, on the other hand, are designed to run and run and run, seemingly to no end. We, in fact, often killed our prey by simply running it down to a point of exhaustion when it would simply lay down and let itself be slaughtered. This is why we largely lost all our body hair and developed the sweating ability — it's so we could cool ourselves and regenerate stamina whilst moving. You'd be surprised how little stamina most wild animals have, most of them are built for short bursts of energy, not long-term expenditure.\n\nThe Neanderthals required around 30% more energy to run and about 10% more energy to sprint, although, admittedly, they could likely sprint much faster than us.\n\nWalking, however, is key here. Their pelvises made it harder to absorb shock from all the walking, and while it's completely reasonable for a human to cross around 30 kilometers in a day, such a feat was virtually impossible for a Neanderthal, at least in a sequence and without rest days in between. We conquered the entire world by walking, it's how we took European territory over, and the Neanderthals simply couldn't cover the distance as fast as we could as they would tire quickly and needed more time to rest.\n\nIt's also widely believed that the Neanderthals never domesticated the dog, and even if they did, it certainly never became mainstream in their societies, which once again takes us back to the fact that they didn't share technology and knowledge with one another as much as we did. By relying on our furry friends, we became much more efficient at hunting, and more food led to more procreation, which led to more territorial spreading.\n\nInterbreeding, which we discussed earlier, played a role as well as Neanderthal-to-human gene flow was much more common than human-to-Neanderthal gene flow, meaning that we were actively taking away members of their species, while rarely giving anyone back. The reason why is not yet known, but this was another way we affected their population.\n\nThere is, of course, the most obvious method of killing a species — war. There have most definitely been conflicts between our two species, probably never at a large scale, but it's likely that entire human tribes were killed by Neanderthals and vice versa. There was for long an idea of the Neanderthal as this ape-like, aggressive, violent subhuman, which couldn't be farther from the truth, but conflicts most definitely did arise once we started closing in territories around them. The dwindling of resources and supplies always leads to that, and it was unavoidable.\n\nThis led to the final nail in the Neanderthal coffin — inbreeding. Once the technological and intellectual advances, our walking ability, the way our societies worked, the spread of our pathogens, and war all took their toll on them and their societies started to dwindle, Neanderthals started breeding amongst themselves. This, in turn, made them even more vulnerable to illnesses and worse at every survival skill necessary, which ultimately drove them to extinction.\n\nWe, of course, aren't the only reason Neanderthals have gone extinct. There's also the Heinrich event four, a massive climate change event that influenced the extinction of many species, and we have to account for the fact that the Neanderthals were unable to improve their hunting methods when faced with scarcity of prey, which is something humans definitely aren't at fault for.\n\nNevertheless, we most definitely lived together and our two species influenced one another's existence massively, while our constant presence in shared territories and our spread across Eurasia contributed to their disappearance, and that makes one wonder would Neanderthals still be around if the human race never existed? That is a question we will likely never know the answer to.\n\n## Key Takeaways\n\n- Humans and Neanderthals cohabitated and interbred, with all non-Sub-Saharan humans carrying Neanderthal DNA.\n- Neanderthals were more adapted to Europe's cold climate and had superior strength and speed.\n- Interbreeding between humans and Neanderthals influenced genetic traits, including immune responses and physical features.\n- Humans contributed to Neanderthal extinction through pathogen spread, territorial expansion, and technological advancements.\n- Neanderthals' extinction was likely due to a combination of human influence and environmental factors.\n\n## Frequently Asked Questions\n\n### What is the common ancestor of Neanderthals and modern humans?\n\nHomo heidelbergensis is widely believed to be the last common ancestor of Neanderthals and modern-day humans.\n\n### Where did Neanderthals primarily live?\n\nNeanderthals spread across both Asia and Europe, with high fossil finding density in Italy, Spain, France, and Germany. They were also capable of establishing long-lasting cultures over 3,000 kilometers in less than 2,000 years.\n\n### How long did Neanderthals and humans coexist?\n\nNeanderthals went extinct roughly 40,000 years ago, meaning humans spent more time with them than without them.\n\n### What evidence supports the cohabitation of Neanderthals and humans?\n\nEvidence from sites like the Tishemet Cave in Israel, the Cave River nature reserve in Israel, and the Ranis site in Germany shows shared territory and interbreeding between Neanderthals and humans.\n\n### What genetic evidence supports interbreeding between Neanderthals and humans?\n\nModern humans, except for Subsaharan Africans, have at least some Neanderthal DNA. Additionally, Neanderthal remains have been found with human mitochondrial DNA, indicating interbreeding.\n\n### How did interbreeding affect human genetics?\n\nInterbreeding with Neanderthals influenced various human traits, including nasal height, hair texture, skin pigmentation, and immune system responses. Some Neanderthal genes also contribute to certain diseases and conditions in modern humans.\n\n### What role did pathogens play in the extinction of Neanderthals?\n\nHumans spread pathogens from Africa that Neanderthals were not equipped to handle, leading to a significant decrease in their population. Neanderthals had a weaker and slower immune system compared to humans.\n\n### How did human technological and societal advantages contribute to Neanderthal extinction?\n\nHumans lived in larger, better-connected groups, allowing for the spread of technology and trade. Neanderthals lived in smaller, isolated tribes with fewer technological improvements over time, making them less efficient in acquiring resources and adapting to changes.\n\n### What was the impact of interbreeding on Neanderthal population?\n\nNeanderthal-to-human gene flow was more common than the reverse, meaning humans were actively taking away members of the Neanderthal species while rarely giving anyone back, contributing to their population decline.\n\n### What is the significance of the Heinrich event in Neanderthal extinction?\n\nThe Heinrich event four, a massive climate change event, influenced the extinction of many species, including Neanderthals. This event, combined with human factors, contributed to their demise.\n\n## Sources\n\n- [Original Side Projects video: People and Neanderthals Lived Together. Here's How We Know.](https://www.youtube.com/watch?v=7B7jBeLTXO8)\n- [Hero image source](https://upload.wikimedia.org/wikipedia/commons/a/ac/Roze_zaterdag._10.000_Homo%27s_en_lesbische_vrouwen_bezochten_Haarlem._NL-HlmNHA_54031661.JPG) by Poppe de Boer / openverse, cc0.\n\n## Related Coverage" url: https://sideprojects.pub/article/people-and-neanderthals-lived-together-heres-how-we-know.md canonical: https://sideprojects.pub/article/people-and-neanderthals-lived-together-heres-how-we-know datePublished: 2026-07-04 dateModified: 2026-07-04 author: - name: Simon Whistler url: https://sideprojects.pub/author/simon-whistler publisher: Side Projects image: "https://media.sideprojects.pub/cdn-cgi/image/width=1600,height=900,fit=cover,quality=80,format=auto/articles/7B7jBeLTXO8/hero.jpg" type: Article contentHash: 268e0e35d983b93748f453a1b82e3e397d3438a122a970e6a169f52f67c8c39e tokens: 9149 summaryUrl: https://sideprojects.pub/article/people-and-neanderthals-lived-together-heres-how-we-know.md.summary.md --- Has anyone ever called you a neanderthal? Well, that's actually not offensive because that person was most likely right. Everyone except for Subsaharan natives has at least some neanderthal DNA mixed in with their own. This is the result of thousands of years of cohabitation and interbreeding between our two species. In a very uniquely human egoistic way, for the longest time we saw Neanderthals as savages and brutes that stood in humanity's way of world dominance and posed a threat to our survival. The reality is, however, quite the opposite. Not only have humans and Neanderthals lived together, but we also influenced one another's genetic code, societal development, and eventually the extinction of one, and biological perseverance of the other species. Neanderthals are, in a way, still alive — here's why. ## Neanderthals and Humans — Two Separate Lineages Although the exact hominid family tree still can't be agreed upon by anthropologists because there are simply too few fossils to provide us with a specific answer, it's widely believed that *Homo heidelbergensis* was the last common ancestor of Neanderthals and modern day humans. *Homo heidelbergensis*, named after the German city of Heidelberg, near which a fossil was found in the early 20th century, evolved simultaneously in Africa and Eurasia from *Homo erectus* around 600,000 years ago. Some 200,000 years later, the African group would evolve into *Homo sapiens*, otherwise known as the person you see in the mirror every time you pass by it, and the other group would separate into two and evolve into Neanderthals and Denisovans. Denisovans are, for clarity, a humanoid species very closely related to Neanderthals. In fact, some anthropologists even wanted to classify them as a Neanderthal subspecies, but they were in fact their own species, and alongside Neanderthals, they're our closest cousins. For hundreds of thousands of years, humans never bothered to leave Africa. Denisovans were largely living in Asia, with Neanderthals spreading across both Asia and Europe, with Italy, Spain, France, and Germany having the highest fossil finding density. This, however, shouldn't limit our view of them as Neanderthals were fantastic nomads, capable of establishing long-lasting cultures over 3,000 kilometers in less than 2,000 years. This might not sound impressive now because such a distance is nothing more than a flight away for you nowadays, but keep in mind that Neanderthals lived roughly 400,000 to 240,000 years ago. They had to cross an unforgiving wilderness on foot, without access to sophisticated tools or weapons. According to the latest stone tool findings, it's entirely possible that Neanderthals have, in fact, lived for much longer than we think — up to 32,000 years ago — and that they inhabited one of the harshest environments on earth, the Arctic. At the same time, Denisovans were establishing communities in modern-day Siberia, Tibet, Taiwan, China, New Guinea, and Australia. Denisovans migrating across the Wallace Line, the natural faunal line between Asia and Australia, is a very recent discovery based on high DNA percentages in modern Australians and Papuans. At the same time, we were…doing nothing. The lazy bastards that we are, we've actually spent the majority of our existence as a species not bothering to venture outside of Africa. Of course, some isolated cultures from northeastern Africa migrated to Southern Europe and the Middle East, but not in big enough numbers to leave a trace. The oldest known trace of such a migration is a human skull found in Greece dated to about 210,000 years ago, but this is an exception rather than a rule. As a species, we spent close to two-thirds of our 300,000-year existence just moving across Africa, and large-enough migration waves that would establish long-term cultures wouldn't occur until about 100,000 years ago. Then, early humans crossed the Bab-el-Mandeb strait between the Arabian Peninsula and the Horn of Africa while the tide was low and spread across the modern day UAE, Oman, and India. The northern route, which crossed the Sinai Peninsula, was also used, and by using those two routes, humans later migrated to Europe and Asia, while those who entered Central Asia later migrated to the north, then crossed the Beringia land bridge, which existed at the time, and spread across modern day North and South America. Here is the very important part, though. Throughout the vast majority of our migration across Europe and Asia, we constantly came across Neanderthals and Denisovans. In fact, they only went extinct roughly 40,000 years ago, which means that, as a species, we actually spent more time with them than without them, and since we bumped into them so many times, cohabitation and interbreeding was unavoidable, and we today know for certain that our cultures lived together. ## Neanderthal and Human Cohabitation The first humans reached the heart of Europe, modern-day Germany, around 45,000 years ago. Five thousand years later, Neanderthals were completely extinct aside from a few pockets of the surviving culture in Iberia. Throughout that short time period, however, some humans shared territory with the Neanderthals instead of competing for it. The Tishemet Cave in modern-day Israel is one of the best examples of Neanderthal and human cohabitation. According to the research team, several groups of humanoids, including humans, Neanderthals, and pre-Neanderthals, maintained ongoing contact for many years. This resulted in the exchange of tools, hunting practices, various rituals, and, of course, DNA. It's highly likely that Tishemet Cave was used as a burial site by both humans and Neanderthals. This is one of the oldest burial places in the world, dating at some 110,000 years old, which is right around the time when the first humans started migrating from Africa to Eurasia, and their path would take them to the cave. Objects such as stone tools, animal bones, and pieces of ochre were found at the site, alongside human and neanderthal remains of roughly the same age. According to Professor Yossi Zaidner, who's in charge of the dig, the Cave was a melting pot for different humanoid populations. There, they regularly came into contact with one another and influenced one another's burial practices. Scientists also believe that Neanderthals and humans shared the modern-day Cave River nature reserve in Israel. There's evidence of interbreeding and technology sharing with stone axes and sharp arrowheads found in both human and Neanderthal caves. More evidence proving good neighbourly relations between humans and Neanderthals comes from Germany. Scientists from Berkeley analyzed DNA from numerous bone fragments found at Ranis, and discovered that they are most definitely human. However, by dating them, they found that the bones are at least 45,000 years old or quite possibly 2,500 older. This would not only make those humans some of the first in Europe, but it would also put that particular human culture at the right place and at the precisely right time to share their immediate area with Neanderthals. A similar thing happened in France about 50,000 years ago. Somewhere on the slopes of the Prealps in southern France, the Mandarin Cave was most likely shared by humans and Neanderthals. By dating the remains, the anthropologists deduced that humans inhabited the cave precisely 54,000 years ago. This means that they were most likely an oddly successful nomad culture that got further west than any human by that point, but this was by no means common and they were an outlier more than anything. Interestingly, local Neanderthals have used the cave both before and after that human culture. According to the article published in *The Conversation*: > "When Neanderthals and modern humans made fires in the site, the smoke would leave a layer of soot on those surfaces. Then the following season a thin layer of calcium carbonate called speleothem would cover it over. This cycle was repeated over and over. A decade of work…has shown that these patterns can be read like tree rings to tell us with what frequency and duration the groups visited the site, demonstrating that human groups came to Mandrin some 500 times over 80,000 years." By reading the layers of soot and calcium carbonate, the scientists were able to determine that no more than a year had passed between the last time the Neanderthals used the Cave and the time the first humans moved in. The humans occupied the cave for about 40 years and likely shared the immediate territory with Neanderthals, and once they abandoned the cave, the Neanderthals moved back in and remained there until extinction. There is also cultural evidence suggesting that Neanderthals were influenced by early humans. Samples taken from some Neanderthal sites include very human-specific artifacts that were never made by Neanderthals, which would suggest that some Neanderthal culture adopted our own habits and copied our technologies. The most obvious proof of us sharing territory with Neanderthals is, however, found in biology. The University of Adelaide ran a DNA study of Neanderthal dental plaque found at the El Sidron cave in Spain and found evidence of a bacteria that causes gum disease and dental caries. The only issue is the fact that the disease should only be present in modern humans and that the remains in question are 180,000 years old. So, how did a 180,000 year-old Neanderthal get a human-specific microbe in his or her mouth? The most apparent answer is that the Spanish Neanderthals grouped with our forager ancestors in Africa. The composition of the oral bacterial population closely correlates to the amount of meat in someone's diet, something that applies to both humans and Neanderthals, and the composition of the microbes from the sample in the north of Spain is extremely similar to ancient humanoid microbe compositions. The other explanation is that the Neanderthal in question exchanged saliva with a human, and that's what takes us to the strongest argument proving that we lived with Neanderthals. There's simply too much evidence of interspecies breeding to ignore. ## Interbreeding and Its Results When the first larger migratory waves of humans arrived in Europe, the Neanderthals were most definitely the superior species. They were pound for pound stronger than modern humans, they were faster, they knew the lay of the land, and since they had already been living in Europe for at least 200,000 years by the time we arrived, they were better adapted for the cold weather. Europe back then was much colder than it is today and very few cultures dared migrate more north than Germany because of the intense cold. Suffice it to say that we needed a little bit of that Neanderthal DNA if we planned on surviving in Europe. According to Ludovic Slimak, an archeologist with the Center for Anthropology and Genomics of Tolouse, when two populations are physically close, but still separated by traditions and language, they are going to exchange women. This is, obviously, extremely sexist, primitive, and inhumane by modern standards, but it is simply the way early human societies functioned. The purpose of exchanging women is the creation of a larger, universal clan, which ultimately makes survival easier for both groups. Although the groups won't necessarily live together, by exchanging members, they're not only exchanging DNA, but knowledge as well. This is a universal phenomenon common with various human clans across history, not just something we can observe with Neanderthals and humans. No single species had the upper hand in the interbreeding. According to the analysis of Y chromosomes of remains found in the Altai Mountains in Russia, Neanderthal Y chromosomes are more similar to the chromosomes of modern humans than the chromosomes of Denisovans, which is odd as Neanderthals and Denisovans are more closely related to one another than either group is to us. Anthropologists still don't know why that is so. The prehistoric 50 Shades of Grey was a two-lane road, however, as some human mitochondrial DNA was found in Neanderthal remains. We know that in humans, mitochondria, which is the part of your cells that turns sugar into usable energy, is exclusively passed down from a mother to her children. If a Neanderthal has human mitochondrial DNA, it proves that they had a human mother. Aside from sharing women, we also shared sexually transmitted diseases with Neanderthals. Professor Ville Pimenoff of the University of Oulu realized this by accident when he was studying the human papillomavirus. All humans have a number of papillomavirus infections throughout our lives, and most of them are asymptomatic. However, the Type 16 HPV is the well-known strain responsible for anogenital cancers. This HPV type is further categorized into five subtypes. AFR-1 and AFR-2 types mostly occur in Subsaharan Africa, while the EUR type occurs in Europe, and guess what? The type dispersion almost perfectly matches the distribution of Neanderthal DNA around the world. Pimenoff calculated that the EUR type of HPV16 first emerged around 60 to 120 thousand years ago, which is right around the time when archaic humans started massively moving into Europe, and it's likely that the strain switched hosts from Neanderthal to *Homo sapiens*. The only way of doing that is by copulating. It's likely that the perpetrators were some of the earliest humans in Europe and Asia who came in contact with Neanderthals in modern-day Iran and Turkey, long before they explored the hearts of the continents. What supports this theory further is the fact that the virus is so cancerous in humans. If you think about it, we only came in contact with the EUR type of HPV16 very recently in our evolutionary history and our immune systems simply haven't yet evolved to fight it properly. So…Neanderthals kind of gave us cancer, but we gave them herpes in return so the interspecies STD ledger kind of balances itself out. Even though neither we nor the Neanderthals were faithful to our own species, we were faithful to our partners. Ancient humans and Neanderthals were both largely monogamous, and we know this for a fact thanks to…ancient penises. Yes, that's right, the anatomy of the male genitalia is actually key to understanding monogamy in mammals. Based on the Neanderthal genetic code research, we know that just like human ones, their penises were smooth. The same cannot be said for the majority of the animal kingdom, but with Neanderthals, it's a sure sign that the females made babies with very few partners, usually just a single one. Before I explain it, you should be warned that you're about to have a fantastically nasty picture painted in your head. So, the penises of most male animals — thank God, not humans — have something called penile spines covering them completely. These spines are essentially tiny barbs that are supposed to clear out the sperm of competing males. Why did evolution come up with this, you wonder? In the wild, when a female animal is ready to make babies, it will usually copulate with more than a single partner, and much of that copulation is non-consensual, by the way — just saying that in case this hasn't ruined wildlife enough for you. It is the goal of every single species to continue the life of that species, and this is something that applies to humans as well, it's ingrained in everyone's DNA, we can't help it. On an individual level, it's every animal's instinct to spread its very own DNA, which is why males compete for the females in the wild — they see them as nothing more than incubators for their offspring. So, in the wild, it's completely natural for a single female to copulate with several males in a very short time period, and these penile barbs are supposed to remove the previous male's sperm. The barbs have a texture very similar to a cat's tongue, so if you've ever been licked by a cat, you know that you should be grateful for not being born as one, and you now finally understand why they're moaning in pain every time they mate. The main point of this penile barb monologue is that we don't have them, and Neanderthals didn't have them either, which means exactly one thing — there is and was not enough genetic competition for our own and Neanderthal evolution to bother with developing barbs. Neanderthal communities usually composed of brothers and cousins and their own female partners and children — there was very little room for promiscuity. If a Neanderthal clan exchanged one of their own female members for a human female, that human female would usually spend the rest of her life with her Neanderthal partner. The result of such an interspecies marriage wasn't often successful, though. According to years of research, the children of human males and Neanderthal females could survive, but the adverse rarely happened. We know this because most humans nowadays have at least some Neanderthal DNA — we'll get to the specifics later — but very few Neanderthal remains with human DNA were ever found. It's believed that the children of male Neanderthals and female humans were most likely sterile. We still don't know why that is, but we might find the answer if we look at other mammalian species. What do you get when you forcibly mate a male lion and a female tiger? A liger. That's not a joke, it's an actual lion-tiger hybrid and it's one of the largest cat species in the world. Calling it a species, however, is biologically incorrect because male ligers are completely sterile, and being capable of reproducing is the most important identifying feature of a species. Mules are similar. They're the offspring of a male donkey and a female horse and they are almost always sterile, although a few medical miracles have been documented. This is in accordance with Haldane's rule, which is one of the most important laws of hybrid biology. That rule states that in species hybridization, if one sex has to be sterile, it will always be the one with different sex chromosomes. This means that male human-Neanderthal hybrids were most likely the sterile ones, while female hybrids could probably successfully mate with other Neanderthals or humans. This explains why human mitochondrial DNA was found in Neanderthal remains. The Neanderthal Y chromosome is one of the reasons why human women could rarely successfully mate with Neanderthal males. According to *Live Science*, the Y chromosome created conditions that might have led to miscarriages. After analyzing the Y chromosome of a Neanderthal male found in Spain, researchers found three mutations that could trigger immune responses from human women during pregnancy, which could lead to a miscarriage. Human males only have one of those three mutations. To simplify it — male Neanderthals were simply incompatible with human women, and just going through the pregnancy and giving birth was, from a medical perspective, a success. The human-Neanderthal mating rate would quickly die down, though. The oldest human remains found in Neanderthal-rich areas and dated to the right time period have the longest stretches of Neanderthal DNA. However, if we fast forward just by a few thousand years, Neanderthal segments in human DNA become much shorter. The two most reasonable explanations are that people with more Neanderthal DNA were simply less fertile, or that breeding with Neanderthals resulted in unwanted features and mutations that we wanted to eradicate, so we avoided mating with human-Neanderthal offspring. We have very little information on what human-Neanderthal hybrids looked like. Even though we have some Neanderthal DNA now, we lack pronounced Neanderthal features. The only two skeletons that give us any idea what a Neanderthal-human person could look like are those of children. A skeleton of a boy, dated to about 24,500 years ago, found near Fatima in Portugal had a stocky torso and short legs, which are characteristic of Neanderthals, but a normal, human chin, jaw, and arm bones. An even older set of remains, one dated to about 40,000 years ago, was found in Romania. The skull is rich with both human and Neanderthal traits, particularly the extremely large molars and a flat head. This individual was between 6 and 9% Neanderthal, and that makes him the person with the highest percentage of Neanderthal DNA ever found, at least so far. Speaking of features, breeding with Neanderthals has most definitely affected our genetics. Taller noses, for example, likely come from Neanderthals. Neanderthals developed tall noses as a way of dealing with the intense cold in Europe, and through mating with them, we inherited one specific gene that determines nasal height. The noses of modern humans are designed to regulate the temperature and humidity of colder air, while our ancestors' noses were smaller because the air in Africa was warmer. Genes affecting keratin have been introgressed from Neanderthals in East Asians and Europeans, effectively determining the way our hair looks. Baldness is still, interestingly, an inherently human thing. The skin pigmentation gene was also affected by Neanderthal genetics. Other genes, such as those involved with the function of sugar metabolism, muscle contraction, enamel thickness, brain size, and body fat distribution, have all been influenced by Neanderthal genes. There are also three Neanderthal genes that result in great pain sensitivity in humans who carry all three variants, while we also share the FOXP2 gene, which, when mutated, leads to speech problems, as well as problems with oral and facial control. Our immune systems were by far the most affected by Neanderthal DNA. By breeding with Neanderthals, we acquired the genetic resistance to certain European diseases that we had never encountered before. This gave the offspring a better chance at survival, but it also resulted in backfiring. Some autoimmune diseases are the direct consequence of breeding with Neanderthals. Graves' disease, for example, which causes the thyroid to produce hormones in excess, can be a result of Neanderthal genes. Even COVID-19 has been affected by this. In 2020, researchers found that the Neanderthal genome plays a huge part as a genetic risk factor for severe COVID. A lot of people who died from COVID were affected by this. Similarly, one of the genes responsible for Duputryen's disease, an illness that causes the thickening and shortening of finger tissue, comes from Neanderthals. Some Neanderthal genes in humans were originally very important but have outlived their usefulness. The clotting gene is one of them. We inherited it from Neanderthals and it was useful when we hunted every day as it allowed the blood to quickly clot and prevent bleeding from small wounds. However, since we're not exactly chasing after reindeer in the woods every day nowadays, this same gene is now useless and even dangerous. It can cause harmful clots to form in the later stages of life. Another Neanderthal gene can cause neurological disorders when the natural sleep cycle is disturbed — this can actually cause depression. It's likely that Neanderthals rarely experienced this because they actually had much better sleeping habits than we do nowadays, but the gene was there. And to end this Neanderthal gene tirade, we'll say that by far the most ridiculous gene is the group of genes regulating everyone's circadian rhythm. So, if you're not a morning person, you might have your Neanderthal ancestor to blame. We inherited pretty similar genes from the Denisovans, with the addition of a few adaptations for survival at high altitudes, and these genetic adaptations are the ultimate proof that we not only spent thousands of years living alongside Neanderthals and Denisovans, but that we bred with them. Today, Melanesians and Aboriginal Australians have, on average, between 4 and 6% Denisovan DNA, with the Ayta Magbukon people having the highest level of Denisovan ancestry in the world, ranging from 30 to 40%. When it comes to Neanderthals, Europeans carry about 1.5 to 2.5% of Neanderthal DNA, while East Asians have more — on average, mind you — with 2.5% being the average. Non-Subsaharan Africans have about 2% Neanderthal DNA, while Subsaharan Africans are the only people in the world with no Neanderthal DNA admixture. Native Americans have between 1.5 and 2% Neanderthal DNA on average with about 0.2% Denisovan DNA. After taking a short trip down ethnicity lane, two thoughts come to mind. First of all, considering that humans are already pretty racist now, can you even begin to imagine how incredibly racist we would be if we had to share the planet with another humanoid species? Just makes you wonder — if some people are losing their minds over skin color, how bad would they get if they met someone whose features are humanlike, but not human. Secondly, we are proof that we lived with Neanderthals, and even though they have gone extinct, they live through us in a way, and, in fact, we are one of the primary reasons they're not here anymore. ## Our Cohabitation Led To the Neanderthals' Demise The "Why have the Neanderthals gone extinct?" question is one that anthropologists have been trying to answer ever since the species was described for the very first time. Although there is no definitive answer to the question yet, and it's reasonable to assume that there will never be one, it's widely believed that the Neanderthal extinction is the result of a combination of factors, almost all of which had something to do with us, the human race. It should be pointed out, just for the sake of chronological clarity, that the Neanderthals went extinct around 40,000 years ago, although a few isolated cultures remained alive for a few thousand years. Those cultures were, however, nowhere near enough to repopulate the entire species. One of the primary ways we contributed to their extinction is by spreading pathogens. Similarly to how we weren't equipped to deal with Europe-based parasites and pathogens when we first arrived on the continent, the Neanderthals weren't equipped to deal with the pathogens we brought from Africa. Since we lived so close together and interbred so many times, we transferred Africa-based pathogens to them that killed them by the thousands. This had a catastrophic effect because the Neanderthal population was never that large, with anthropologists saying it ranged from 3,000 to 12,000 adults. They had a naturally lower fertility rate and had fewer children than humans who, as now know, went at it like rabbits. The Cro-Magnons, which are the first ever humans to come into contact with the Neanderthals, outnumbered their local adversaries ten to one. This means that the Neanderthals were quite literally surrounded by a bunch of pathogen fountains that were taking over territory and spreading like wildfire. The natural question here is if Neanderthal populations were decimated by our illnesses, why didn't the same thing happen to us? It did, actually, to a degree, but by the time we first arrived in Eurasia, we were much better equipped to handle new illnesses thanks to something called the 'African advantage'. The disease load of the African tropics was much higher and humans evolved a stronger and overall better immune system in comparison to Neanderthals. Our immune system was also better at adapting, and it did that fairly quickly, and we also plugged the holes in it by breeding with Neanderthals and getting genes that would help our immune systems deal with Eurasia-specific pathogens. Neanderthal immune systems were specialized for local pathogens, but they faced fewer and less severe illnesses, which made them comparatively weak and slow, which partly led to their demise. A very similar thing happened to Native Americans when they first came into contact with Europeans. Another way we contributed to the Neanderthals' extinction is by simply taking over their territory. Although we didn't necessarily engage in a war, and we even interbred with them, it's in our nature to expand territory in order to secure our survival, which is exactly what happened here. We lived in larger groups which were better connected to one another and allowed trading, as well as the spread of technology. Neanderthals lived in smaller, isolated tribes — their tools were sophisticated, yes, but there were very few technological improvements over time. We were most definitely beating them in the technological race. They were also less efficient in acquiring resources as some Neanderthal tribes didn't divide labour based on sex. Females were often hunting with males, and this was during an era when you had to run for miles on end to tire out a deer or a doe and have enough strength to drag it back home, so it's safe to say things could have been done more efficiently. Speaking of running, this was a massive disadvantage for the Neanderthals as their bodies were built for fighting and wrestling, not for half-marathons. Humans, on the other hand, are designed to run and run and run, seemingly to no end. We, in fact, often killed our prey by simply running it down to a point of exhaustion when it would simply lay down and let itself be slaughtered. This is why we largely lost all our body hair and developed the sweating ability — it's so we could cool ourselves and regenerate stamina whilst moving. You'd be surprised how little stamina most wild animals have, most of them are built for short bursts of energy, not long-term expenditure. The Neanderthals required around 30% more energy to run and about 10% more energy to sprint, although, admittedly, they could likely sprint much faster than us. Walking, however, is key here. Their pelvises made it harder to absorb shock from all the walking, and while it's completely reasonable for a human to cross around 30 kilometers in a day, such a feat was virtually impossible for a Neanderthal, at least in a sequence and without rest days in between. We conquered the entire world by walking, it's how we took European territory over, and the Neanderthals simply couldn't cover the distance as fast as we could as they would tire quickly and needed more time to rest. It's also widely believed that the Neanderthals never domesticated the dog, and even if they did, it certainly never became mainstream in their societies, which once again takes us back to the fact that they didn't share technology and knowledge with one another as much as we did. By relying on our furry friends, we became much more efficient at hunting, and more food led to more procreation, which led to more territorial spreading. Interbreeding, which we discussed earlier, played a role as well as Neanderthal-to-human gene flow was much more common than human-to-Neanderthal gene flow, meaning that we were actively taking away members of their species, while rarely giving anyone back. The reason why is not yet known, but this was another way we affected their population. There is, of course, the most obvious method of killing a species — war. There have most definitely been conflicts between our two species, probably never at a large scale, but it's likely that entire human tribes were killed by Neanderthals and vice versa. There was for long an idea of the Neanderthal as this ape-like, aggressive, violent subhuman, which couldn't be farther from the truth, but conflicts most definitely did arise once we started closing in territories around them. The dwindling of resources and supplies always leads to that, and it was unavoidable. This led to the final nail in the Neanderthal coffin — inbreeding. Once the technological and intellectual advances, our walking ability, the way our societies worked, the spread of our pathogens, and war all took their toll on them and their societies started to dwindle, Neanderthals started breeding amongst themselves. This, in turn, made them even more vulnerable to illnesses and worse at every survival skill necessary, which ultimately drove them to extinction. We, of course, aren't the only reason Neanderthals have gone extinct. There's also the Heinrich event four, a massive climate change event that influenced the extinction of many species, and we have to account for the fact that the Neanderthals were unable to improve their hunting methods when faced with scarcity of prey, which is something humans definitely aren't at fault for. Nevertheless, we most definitely lived together and our two species influenced one another's existence massively, while our constant presence in shared territories and our spread across Eurasia contributed to their disappearance, and that makes one wonder would Neanderthals still be around if the human race never existed? That is a question we will likely never know the answer to. ## Key Takeaways - Humans and Neanderthals cohabitated and interbred, with all non-Sub-Saharan humans carrying Neanderthal DNA. - Neanderthals were more adapted to Europe's cold climate and had superior strength and speed. - Interbreeding between humans and Neanderthals influenced genetic traits, including immune responses and physical features. - Humans contributed to Neanderthal extinction through pathogen spread, territorial expansion, and technological advancements. - Neanderthals' extinction was likely due to a combination of human influence and environmental factors. ## Frequently Asked Questions ### What is the common ancestor of Neanderthals and modern humans? Homo heidelbergensis is widely believed to be the last common ancestor of Neanderthals and modern-day humans. ### Where did Neanderthals primarily live? Neanderthals spread across both Asia and Europe, with high fossil finding density in Italy, Spain, France, and Germany. They were also capable of establishing long-lasting cultures over 3,000 kilometers in less than 2,000 years. ### How long did Neanderthals and humans coexist? Neanderthals went extinct roughly 40,000 years ago, meaning humans spent more time with them than without them. ### What evidence supports the cohabitation of Neanderthals and humans? Evidence from sites like the Tishemet Cave in Israel, the Cave River nature reserve in Israel, and the Ranis site in Germany shows shared territory and interbreeding between Neanderthals and humans. ### What genetic evidence supports interbreeding between Neanderthals and humans? Modern humans, except for Subsaharan Africans, have at least some Neanderthal DNA. Additionally, Neanderthal remains have been found with human mitochondrial DNA, indicating interbreeding. ### How did interbreeding affect human genetics? Interbreeding with Neanderthals influenced various human traits, including nasal height, hair texture, skin pigmentation, and immune system responses. Some Neanderthal genes also contribute to certain diseases and conditions in modern humans. ### What role did pathogens play in the extinction of Neanderthals? Humans spread pathogens from Africa that Neanderthals were not equipped to handle, leading to a significant decrease in their population. Neanderthals had a weaker and slower immune system compared to humans. ### How did human technological and societal advantages contribute to Neanderthal extinction? Humans lived in larger, better-connected groups, allowing for the spread of technology and trade. Neanderthals lived in smaller, isolated tribes with fewer technological improvements over time, making them less efficient in acquiring resources and adapting to changes. ### What was the impact of interbreeding on Neanderthal population? Neanderthal-to-human gene flow was more common than the reverse, meaning humans were actively taking away members of the Neanderthal species while rarely giving anyone back, contributing to their population decline. ### What is the significance of the Heinrich event in Neanderthal extinction? The Heinrich event four, a massive climate change event, influenced the extinction of many species, including Neanderthals. This event, combined with human factors, contributed to their demise. ## Sources - [Original Side Projects video: People and Neanderthals Lived Together. Here's How We Know.](https://www.youtube.com/watch?v=7B7jBeLTXO8) - [Hero image source](https://upload.wikimedia.org/wikipedia/commons/a/ac/Roze_zaterdag._10.000_Homo%27s_en_lesbische_vrouwen_bezochten_Haarlem._NL-HlmNHA_54031661.JPG) by Poppe de Boer / openverse, cc0. ## Related Coverage