Scientists Studied An 800,000-Year-Old Tooth – And It Has Reconstructed The Human Family Tree

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Something as small as a tooth is about to shed light on human evolutionary history. But it’s not the look of this particular dental remnant that answers scientists’ questions. Instead, the experts have developed a process to analyze the enamel of this 800,000-year-old chomper. And the results will clarify the standing of an ancient, meat-eating ancestor, whom we only discovered as recently as 1994.

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Experts have long known that the closest living relatives to humans are chimpanzees and that the two species split apart approximately 7 million years ago. But the evolutionary changes between primates and humans aren’t clear-cut. And as such, researchers and scientists have spent years exploring the possibilities of how we got from point A to B.

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Now, there are some definite plot points along the way. One of the most famous fossil finds of all was Lucy – a partial skeleton discovered in Ethiopia and estimated to be 3.2 million years old. Lucy had had long arms and a chimpanzee-sized brain, but experts could tell that she’d walked on two legs – unlike a primate.

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In finding Lucy, experts happened upon a partial skeleton of one of our ancestors, the Australopithecus. In the case of this more recent development, though, all they had to work with was a tooth. And as such, it would take years of careful analysis to yield fruitful results.

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But the tooth had just enough genetic information to help scientists learn more about a particular species. And while studying this sole dental record, they realized that another space was needed on the human family tree. Indeed, from chimpanzees to Lucy and all the way through to modern-day man and woman, a new piece of this vast jigsaw had popped up.

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So scientists have long known that Neanderthals and their sister species, the Denisovans, shared a common ancestor with modern humans. But the placement of the species Homo antecessor never quite fit into the mix. In fact, fossils of the latter species were only discovered in 1994 at an ancient site in Spain.

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Neanderthals, for one, roamed the Eurasian continent up until about 40,000 years ago. The Denisovans lived only in Asia, and some of them may have survived until 30,000 to 15,000 years ago. The Homo antecessor lived long before either, though – estimates have them in Western Europe from 1.2 million to 800,000 years ago.

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Now, Paleoanthropologists first uncovered remnants of the Homo antecessor during a dig in Spain’s Sierra de Atapuerca region. Specifically, the team – made up of José María Bermúdez de Castro, Eudald Carbonell and Juan Luis Arsuaga – excavated a massive cavern on-site called the Gran Dolina.

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And Gran Dolina has 11 different layers of rock in the ground, most of which feature fossil remnants of either animal or human inhabitants. On the sixth layer, Bermúdez de Castro, Carbonell and Arsuaga found remains from the latter category. Furthermore, they dated the ancient remains to approximately 780,000 years ago, which qualified them as the oldest human fossils found in Europe.

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This particular species became known as Homo antecessor. Of course, “homo” means “human,” while “antecessor” is Latin for “early settler,” “pioneer” or “explorer.” The name fit, considering the remnants were Europe’s oldest. So far, they are the continent’s first-known human population, making them trailblazers. And, with further analysis, they surprised experts in more ways than one.

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You see, the Homo antecessor didn’t have a particular physical feature that separated it from other early human species. However, it did have a unique combination of details – particularly in the teeth, cranium and lower jaw – that made it unlike other ancient people. In fact, some of their traits appeared more closely linked to modern humans.

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For instance, the Homo antecessor had a brain approximately 1,000 cubic centimeters in size, compared to a modern human’s, which measures in at 1,350cc. Their frame was likely “similar to modern humans, but more robust,” according to the Australian Museum’s website. And men belonging to this ancient species had rather short stature, typically measuring in at five foot two to five foot nine.

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What’s more, the face of the Homo antecessor looked relatively modern, too, especially in the middle part of its visage. They also had noses that projected outward and cheekbones that appeared hollowed, just like today’s humans. But that’s where the similarities end, and more ancient-looking characteristics start making their way in.

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For example, the Homo antecessor had a short forehead, as well as a brow ridge with double markings – a trait mirrored in Neanderthals, as well as in the Chinese Homo erectus. Also, the oldest European fossils indicated that the species had robust teeth, with long incisors shaped like shovels on the top half of their jaws.

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Mind you, the Gran Dolina site provided clues as to how the Homo antecessor lived during their day, too. Archaeologists dug up the skeletons of multiple large animals, all of which would’ve been carried to the site intact. This indicated that the species didn’t operate with an every-man-for-himself mentality. Instead, they worked together to survive, and they ate together, too.

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Specifically, it seemed that the Homo antecessor would go out in groups to hunt, then carry back their successful kills. This showed that they had some sort of social structure, dividing up labor and sharing their food amongst each other. And experts could see that they ate species such as wild boar, mammoth, wolves, bear, hyena and deer.

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But in contrast, the remains at Gran Dolina appeared to show that Homo antecessor had a brutal side to its nature, too. Yes, some of the remains of the species had cut marks and evidence of crushing and burning. This evidence seemed to show that they had cannibalistic tendencies.

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Of course, the Homo antecessor’s cannibalism could have been an extreme measure in a life-or-death situation. There’s certainly no indication that it was performed in rituals. And even so, other ancient species also exhibited this type of behavior. Neanderthals, for instance, partook in routine cannibalism, it’s believed, and sometimes ritual defleshing of bodies, as indicated by cut marks on their uncovered skeletons.

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As such, the paleoanthropologists who found the Homo antecessor fossils did some initial dating of the species. And they figured that it stood as the final link between humans and Neanderthals before they split into their own respective species. You see, the similarities between Homo antecessor and Neanderthal bones couldn’t be ignored.

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But the conversation didn’t end there. Instead, anthropologists embarked on a protracted debate as to where Homo antecessor fit into the human family tree. And the conversation progressed as newer studies revealed the facial similarities between modern humans and the ancient species – and the dissimilarities between them and Neanderthals.

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So, a new set of scientists from the University of Copenhagen and the Spain-based team at the National Research Center on Human Evolution took a fresh look at the Homo antecessor’s fossilized remains. This time, they didn’t compare fossil shapes or outward appearances – they utilized protein contained within a single preserved tooth.

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Specifically, the experts relied on a technique called palaeoproteomics or mass spectrometry, which the University of Copenhagen had developed themselves. This allowed them to pull even the tiniest piece of molecular evidence from the 800,000-year-old tooth, which could, in turn, link or unlink the known species of ancient humans.

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In this case, experts plucked proteins left behind in the Homo antecessor’s tooth. Then, they rebuilt the amino acid sequences found in these strands. In turn, they did the same with the amino acids found within proteins from modern humans, Neanderthals and Homo heidelbergensis, a species that lived from 700,000 to 300,000 years ago.

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For modern humans, though, the researchers didn’t have to pull the proteins from enamel – they already had full DNA sequencing to work with. Ideally, it would have been easier to do the same with the Homo antecessor’s genetic code, too, but such information did not stand the test of time as the enamel-bound protein did.

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Comparing ancient and modern proteins in their respective sequences would answer some lingering questions for researchers. Namely, they would be able to place Homo antecessor in the line-up – were they a sister species to the human race, or did they fit in elsewhere? Knowing this would also bring clarity to the debate which has rumbled on for years since the 1994 discovery in Spain.

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As previously mentioned, experts have known for a while that humans and chimpanzees evolved from a common ancestor – who split into two species roughly nine to seven million years ago. Beyond that, they have known frustratingly little about how the species developed to become their modern selves – and how many other iterations of humans and primates lived and died in the process.

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Indeed, the study’s leading author and associate professor of the University of Copenhagen’s Globe Institute, Enrico Cappellini, spoke to Science Daily about previous limits to the research. He said, “Much of what we know so far is based either on the results of ancient DNA analysis, or on observations of the shape and the physical structure of fossils.”

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Before their experiment with the Homo antecessor’s 800,000-year-old tooth, experts hadn’t been able to look back that far into history. Cappellini further explained, “Because of the chemical degradation of DNA over time, the oldest human DNA retrieved so far is dated at no more than approximately 400,000 years.”

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Luckily, though, the updated methodology would reveal sequencing that stretched back further in time than ever before. Cappellini said, “Now, the analysis of ancient proteins with mass spectrometry, an approach commonly known as palaeoproteomics, allow us to overcome these limits.” And in this case, a sample of enamel had become a perfect opportunity.

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Still, it took a decade for the project to come to fruition. Paper co-author Jesper Velgaard Olsen collaborated with Cappellini as they carefully extracted the material they needed from the ancient tooth. Olsen put it simply, saying, “This study is an exciting milestone in palaeoproteomics.”

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As Olsen went on to explain, “Using state of the art mass spectrometry, we determine the sequence of amino acids within protein remains from Homo antecessor dental enamel. We can then compare the ancient protein sequences we ‘read’ to those of other hominins, for example Neanderthals and Homo sapiens, to determine how they are genetically related.”

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As such, palaeoproteomics finally explained where Homo antecessor fell into the lineup of ancient humans all the way to modern times. Study co-author and post-doctoral research fellow at the University of Copenhagen Frido Welker told Science Daily, “Ancient protein analysis provides evidence for a close relationship between Homo antecessor, us [Homo sapiens], Neanderthals and Denisovans.”

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And Welker said that the protein analysis helped to clarify that relationship. He said, “Our results support the idea that Homo antecessor was a sister group to the group containing Homo sapiens [us], Neanderthals, and Denisovans.” So you see, this differed from the original conclusion that Homo antecessor was the final shared ancestor between Neanderthals and modern-day humans.

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Bermúdez de Castro – one of the original paleoanthropologists to find the first remnants of the Homo antecessor – served as the paper’s co-corresponding author. He said, “I am happy that the protein study provides evidence that the Homo antecessor species may be closely related to the last common ancestor of Homo sapiens, Neanderthals, and Denisovans.”

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It was particularly exciting, considering the Homo antecessor appeared so much earlier than the Neanderthals and Denisovans. Bermúdez de Castro went on to say, “The features shared by Homo antecessor with these hominins clearly appeared much earlier than previously thought. Homo antecessor would therefore be a basal species of the emerging humanity formed by Neanderthals, Denisovans and modern humans.”

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Of course, for the researchers behind this milestone project the eye-opening results were just the beginning. You see, the University of Copenhagen team said afterward that they want to develop their protein-extracting method further so that they can re-evaluate other fossils and bones. Because perhaps those remains have more information to share after all.

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Furthermore, Cappellini told Science News that the bone-centric research “would be extremely interesting.” It could potentially link even more ancient humans together, from the Neanderthals to the Homo antecessor to the 3.2-million-year-old Lucy skeleton and beyond. You see, it’s all about harnessing as good a protein sample as possible.

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That’s right, and Cappellini explained this further. He said, “The more proteins we can extract from the fossils, the more we can say about the prehistoric humans, and the more easily we can construct our own family tree for the time since we diverged from the chimpanzees between seven and nine million years ago.”

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Indeed, Homo antecessor was just scraping the surface, as far as research into human history could go. And Cappellini hoped to one day analyze proteins from the two-million-year-old Homo erectus to the Australopithecus (Australopiths), a species of hominins that roamed Africa from four to 1.9 million years ago. As we mentioned earlier, Lucy was one of them.

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According to Science Daily, the University of Copenhagen had the funding to continue its protein-centric research. Perhaps its team would uncover many more connections between modern humans and the species that brought us here today. Cappellini, for one, was excited. He concluded, “I really look forward to seeing what palaeoproteomics will reveal in the future.”

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While the analysis of ancient proteins helped piece together the journey of evolution, this next study gets right to the heart of our origins. Experts have long thought that humankind originated in Africa, you see, but DNA evidence now seems to prove otherwise. And the truth may just surprise you.

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A massive lake glistens beneath the sun, cutting a clear expanse across an otherwise lush wetland, some 200,000 years ago. Here, a new species – Homo sapiens – has gathered. These modern humans have evolved from their Neanderthal ancestors, and humankind has at last started its reign. Yet scientists have just now pinpointed the surprising place where it all began.

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In fact, geneticist Vanessa Hayes of the Garvan Institute of Medical Research in Sydney led a study that used specific scientific data to pinpoint this exact verdant locale. In particular, Hayes and her expert team had to rely on mitochondrial DNA, which they had gathered from the cells of 1,217 samples. This battery-shaped genetic material passes from mothers to their children, so the researchers naturally had to find a population with a maternal line that stretched far into the past.

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With the right DNA information gathered and analyzed, then, the research team highlighted a general area of origin. And after that came further archaeological and geological research that in turn helped Hayes and co to find something spectacular: evidence of a massive, ancient lake that broke down into wetlands. Its lush greenery was the backdrop for the first humans to walk the Earth, they say, and its modern-day location may just surprise you.

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Experts have, of course, long believed that humankind traced all the way back to the African continent. But mapping evolutions and migrations has been a difficult task, to say the least. It was about seven million years ago when human beings began to evolve, after all, splitting off from primates such as the chimpanzee and the bonobo.

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So it’s virtually impossible to find every link between humans and primates, since scientists simply don’t have enough fossil records to achieve this. In fact, entire species may have come and gone without leaving a trace for experts to uncover today. That’s why, in some cases, there are only bits and pieces of evidence to work with.

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Yet the picture of humankind’s ancestral roots becomes clearer as scientists move nearer to the present day. They know, for example, that Neanderthals roamed Europe and even trekked into Siberia and Central Asia – although not as far as Africa. But while this population may have paved the way for modern humans, they did not actually originate the species.

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Instead, it would be the evolution of Homo heidelbergensis and Homo erectus that gave way to Homo sapiens. And these new humans presented a variety of slight differences that separated them from the likes of the Neanderthal population who roamed the continent before them. For one, Homo sapiens took on a more slender build than the stockier Neanderthals up north.

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In addition, modern humans mastered the art of making tools in a way that Neanderthals hadn’t. The African contingent styled their weapons to have sleek, elongated blades, for example. They also fashioned their weapons into more sophisticated throwing spears – which made their hunting more effective. The Neanderthals, by contrast, wielded clunkier weapons that had been chiseled from large stones.

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But the fact that both the Homo sapien and Neanderthal populations had similar lifestyles did initially confound modern-day experts. As a result, then, scientists formulated two main theories about how and where humankind had developed. Some believed in what’s called the multi-regional hypothesis. This states that human ancestors spread across the globe – thus allowing modern humans to evolve in a handful of different places worldwide.

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Then there is a single-origin concept known as the Out-Of-Africa theory. As the name suggests, this idea purports that modern humans grew and evolved on the continent for millennia before migrating to other areas of the Earth. And during the 1980s, scientists seemed to have gathered what appeared to be a clear confirmation of the Out-Of-Africa theory.

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This was due to DNA testing. In fact, DNA testing completely revolutionized science in a number of ways. In terms of determining humankind’s ancestral roots, though, scientists could – using these tools – analyze the genetic information of modern populations. From there, they traced multiple subjects’ lineages back into the distant past, and these mappings seemingly always led researchers to one place of origin: Africa.

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In these original studies, too, experts relied on mitochondrial DNA when tracing their subjects’ ancestral lineages. This part of the genetic code comes from people’s mothers. In addition, this section of DNA will present mutations more readily than others. So it’s therefore easier to follow how mutations have passed from mothers to children for generations.

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In fact, in repeatedly tracing this mitochondrial DNA back all the way to the cradle of civilization, experts realized that one woman’s genetic code has been carried through to everyone on Earth today. She’s known to scientists as “Eve” – although she’s not the same as the biblical figure. She is not considered as the first ever human woman on Earth, after all.

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Rather, this Eve lived when the entire human population consisted of a mere 10,000 people. So Eve was neither the only – nor the oldest – of our ancient predecessors. She just happened to have an unbroken line of daughters who passed her mitochondrial DNA onto their baby girls and down through the ages right through to the present day.

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In short, Eve is regarded as humankind’s “most recent common ancestor,” according to Smithsonian magazine. A 2008 DNA analysis confirmed, too, that she is the only woman of that time to have an unbroken lineage of daughters. And the scientists behind the study also concluded that Eve had originated in Africa – more specifically, the eastern area of the continent.

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Eve’s DNA therefore seemed to reveal the start of humankind’s story. Yet the experts had lots of other questions. If the species originated in Africa, for instance, how did they spread out to other continents? And why are such a disproportionate number of fossils from Europe? To answer these queries, then, the researchers combined the same DNA evidence with archaeological finds.

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And all of this information pointed to major migrations that started between 60,000 and 80,000 years ago. At that time, then, modern humans seemingly left their African origins for Asia. By about 45,000 years ago, though, they had already moved into Australia, Indonesia and Papua New Guinea, too. Then, 5,000 years after that, bands would leave Africa for Europe.

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Humans who journeyed from Africa to Europe likely took one of two pathways to get north. Some would have traced the Mediterranean coast to get onto the continent, while others probably passed through Turkey and along the Danube. Their insurgence also pushed Neanderthals into a few mountainous areas – until the species disappeared altogether about 25,000 years ago.

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The final step in humankind’s journey would bring them to the Americas. This happened about 15,000 years ago and actually began in Asia. From there, you see, Homo sapiens traveled across the Pacific to reach North America. And once on land, some members of the species continued to wander until they settled in South America as well.

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It’s hard to believe that all of this information comes with little fossil evidence of the first humans who started it all. And this is especially surprising considering the changes that have occurred on the African continent – where humankind is said to have originated. Today, in fact, the dry landscape easily erodes and reveals the bones of those who died there centuries ago.

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Yet archaeologists have had little luck in uncovering the remains of the earliest Homo sapiens – whether they dig in Africa or in Europe. Still, the experts believe that the first humans maybe did not bury their dead like the Neanderthals, choosing instead to cremate them or leave them to decompose out in the open.

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In spite of this lack of skeletal remains, though, modern science and technology has allowed researchers to pinpoint human origins. Yes, a 2019 study helmed by geneticist Vanessa Hayes of the Garvan Institute of Medical Research in Sydney relied once again on mitochondrial DNA for answers.

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As previously mentioned, Hayes and her team gathered 1,217 mitochondrial DNA samples from people who currently live in southern Africa. Some of the test subjects even came from the Khosian population – an indigenous group who speak with clicking consonants and have long foraged for their sustenance.

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From those samples, Hayes and the team traced what’s known as the L0 lineage in the subjects’ mitochondrial DNA. The L0 lineage goes all the way back to Eve – humankind’s common ancestor. Over time, then, Eve’s original DNA split into five main branches as people left Africa and diversified.

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The L0 line, as it’s called, also has its own deviations. For instance, it branched about 130,000 years ago, when some of the human population moved from their original homes as heavy rains transformed dry lands into vegetation that could support human life. While some people followed this greenery to the southwest, though, others moved northeast to become farmers and foragers.

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But the L0 mitochondrial DNA started somewhere, and Hayes and her team were able to pinpoint precisely where. Generally, they found that L0 and all of its sub-branches once again placed the earliest humans in Africa. Its territory in fact stretched from Namibia into Botswana and then on to Zimbabwe.

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Then Hayes and the research team added geological, fossil and archaeological evidence into their findings. And while some of the areas of interest may seem uninhabitable in the modern era, the information gleaned about this potential point of human origin showed that it used to look very different.

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The massive Lake Makgadikgadi – roughly the size of New Zealand – once covered a huge swathe of modern-day Botswana. About 200,000 years ago, though, it started to transform from lake into wetland. And according to Hayes and her team, this marshy expanse was the cradle of modern humankind.

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Looking at the region today, however, it’s hard to believe that the origins of human life on Earth could have grown from this arid area. The one-time wetland sits south of the Zambezi River, and it’s nothing like it was in its water-logged past. Instead, it has dried up into sprawling salt pans, with white expanses of the mineral glistening in the sun.

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According to Hayes, though, the area looked a lot different 200,000 years ago. In place of the unforgiving salt pans was a resource-laden wetland. As she told The Guardian in 2019, “It would have been very lush, and it would have provided a suitable habitat for modern humans and wildlife to have lived.”

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At the time, Hayes says, the Botswana-based wetland would have served as an oasis for the arid area surrounding it. So humankind may have started there 200,000 years ago and remained in the area for 70,000 more years. But it’s believed that a shift in climate eventually pushed the founding humans from the wetlands.

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As the Earth’s orbit and tilt shifted, in fact, it brought rains to new stretches of African land. Precipitation then encouraged plant growth, which sprung up in lengthy, lush corridors. These green pathways then gave humans a reason to branch out of their wetland homes and into new territories. This was a precursor to their great global migration, which began about 60,000 to 80,000 years ago.

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Essentially, then, Hayes and her team reiterated the long-held origin of humankind’s roots – but they pinpointed the spot as a wetland in Botswana. Hayes said, “We have known for a long time that modern humans originated in Africa and roughly 200,000 years ago, but what we hadn’t known until this study was where exactly.”

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Not all experts felt convinced by Hayes’ research, however. Chris Stringer, an expert in human origins at London’s Natural History Museum, admitted that modern DNA samples might not be entirely representative of the past. He explained, “I’m definitely cautious about using modern genetic distributions to infer exactly where ancestral populations were living 200,000 years ago – particularly in a continent as large and complex as Africa.”

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Stringer also felt that Hayes and her team had been overly reliant on the mitochondrial DNA – and L0 lineage – as the main factor in their research. He cautioned, “Like so many studies that concentrate on one small bit of the genome, or one region, or one stone tool industry, or one ‘critical’ fossil, it cannot capture the full complexity of our mosaic origins once other data [is] considered.”

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Other studies have also traced humankind’s ancestors back to other pockets of the African continent. In fact, Stringer highlighted a study that focused on the Y chromosomes that only men inherit. This research actually suggested that migration had commenced from west Africa – quite a distance from landlocked Botswana in the south.

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Another study also found that those who left Africa for other lands carried genomes that traced back to the continent’s eastern areas. Stringer concluded, “These and many other data suggest that we are an amalgam of ancestry from different regions of Africa with, of course, the addition of interbreeding from other human groups outside the continent.”

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Ultimately, Stringer called Hayes’ findings an “over-reach.” He told BBC News, “You can’t use modern mitochondrial distributions on their own to reconstruct a single location for modern human origins. I think it’s over-reaching the data because you’re only looking at one tiny part of the genome, so it cannot give you the whole story of our origins.”

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Some scientists also still believe that humankind came from more than one single place. In fact, University of Cape Town archaeologist Rebecca Ackermann told The Guardian that our roots could be in Africa – and beyond. She noted, “Drawing sweeping conclusions about places of origin from analyses of this tiny part of the modern genome is deeply problematic and outdated.”

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Nevertheless, Hayes’ study did pinpoint one potential origin for humankind – and many experts have long believed that the species did, indeed, evolve in Africa. Yet even with modern science and DNA testing, it still may prove an impossible question to answer definitively. For now, though, we can consider life as it may have been 200,000 years ago – with the first humans finding their way in a Botswana wetland.

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