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Have you ever wondered where we humans got our start? I mean, it's Africa. We know that. But Africa is a big place. So the follow up question is, where specifically in Africa did we come from? What seems like a simple question isn't. There are multiple theories and a lot of evidence pointing in different directions. But there's a group of people living in Southern Africa today who are the most genetically diverse population on the planet. And a clue about our origins may be hidden in their genes. [intro music] Before we get too far along, I'll clarify that we're going to be specifically focusing on the origin story of our human species, Homo sapiens.
A number of close relatives of ours that collectively made up an archaic human group, all in our same genus. With all those other archaic humans wandering about, it can be tricky to not only figure out when we branched off from our last common ancestor, but more specifically when we truly became us, both anatomically and behaviorally. But at least we know generally where to start. Because when we're talking about the origin of humans, there's no doubt that we come from Africa. From fossil and material remains to full genomes sequenced from today's human populations and as well as from early human remains, our African origin is crystal clear.
Not that it was always the most popular idea with everyone, but we don't have time for all that. But even after everyone finally agreed that our species came from Africa, there was still debate around how much of our species really started there. Basically, it was a battle of the hypotheses, with two very different ideas about what the origination of our species looked like. One of these was the multiregional hypothesis, championed for decades by Milford Wolpoff. This hypothesis emerged in the 1980s and was tweaked in the early 2000s, but the overall vibe stayed the same.
The idea is that although our ancestral history began in Africa, our modern species didn't rise from a single place, but spread across continents. Basically, the species that we came from left Africa before it was… us. Then they got to all these cool new places but kept in touch with their relatives across the world, enough that all those populations still could be considered one species. But because they were so far apart, each of those populations evolved really different traits, which basically explains how these so-called "identifiable geographic differences" could show up. If you think this sounds like a roundabout way
of trying to validate preconceptions of human races…. Well, you might be onto something there. And while Wolpoff and his supporters have stuck by this hypothesis for the long haul, the much more widely accepted explanation of modern human origins is the Out of Africa theory. Out of Africa proposes that our ancestors who migrated around the world were already full fledged modern Homo sapiens, no regional evolutionary stuff needed. And the evidence for this version of events is pretty strong. For one, we have the fossils. The oldest Homo sapiens fossils all come from Africa, and it's not even close. The earliest Homo sapiens fossils found in Africa, which combine modern and archaic features, a re around 315 thousand years old.
Meanwhile, the oldest one from outside of Africa, found in southeast Europe, was closer to 210,000 years old, so no contest there. And as best we can tell, the population of our ancestors where that European fossil came from was a dead end. If this was a multi-region situation, you'd expect there to have been people living in that area after the time that fossil was found, and that isn't the case here. Even though modern Homo sapiens first appeared in Africa more than 300,000 years ago, it took hundreds of thousands of years for any human populations to really get going anywhere else outside of the continent.
Which means that any direct, fossil based arguments for multi-regional origins are just not well supported. But what really sealed the deal on Out of Africa was the rise of DNA analysis, because we could use that DNA evidence to look for patterns in the genetic variation between populations. Every time a population splits up, that departing population goes through what's called the founder effect. Basically, this smaller fragment of the original population can only bring so much genetic material with them from their original gene pool, so the migrant group won't be as genetically diverse as the group they came from was.
From there, that group might split off again as they continue to move into new regions, and their gene pool narrows once again. So if some of our ancestors were to do something like, oh I don't know, leave their area of origin in a mass migration event, we can just follow the genetic trail backward from least to most variation to find where that original home was. A great place to start looking for that genetic evidence is our mitochondria. They are, of course, the powerhouse of the cell, but they also have their own DNA inside them, which is different from the chromosomes we have in our cell nuclei. And we only inherit our mitochondrial DNA from our mothers,
regardless of whether the offspring are male or female. This makes mitochondrial DNA very handy for tracking genetic inheritance patterns across populations. You do this by looking at the genetic haplogroups; clusters of tightly linked genes inherited together from a particular location on DNA. Mapping out the haplogroups looks like any other evolutionary tree, because that's basically what it is. And if you follow it all the way back, you can find the very earliest groups that gave rise to all the rest of them further down the tree.
Those giant groups are called macrogroups. The oldest macrogroup humans have is macrogroup L, which has eight lineages, L0 to L7, You can find people living in Africa today whose mitochondria come from any of those lineages. So if you can trace your ancestry back to Africa directly, you could have DNA from any haplogroup. But for the non-African folks, it's another story. All the other historic and prehistoric populations of humans outside Africa can trace their mitochondrial DNA to just one group, L3.
Scientists believe people with that L3 haplogroup migrated into Europe and Asia 55 to 85 thousand years ago. And as far as we can tell, all the haplogroups found in people indigenous to places outside Africa branched off from that single group. And to be clear, there's been plenty of mixture of populations in and out of Africa since then, so we're talking about the oldest established groups of people to hang out outside Africa full-time. we would expect a lot of deep lineages of mitochondrial DNA, since all the populations around the world would have been interbreeding for so long that all the diversity got spread around.
Instead, we have one of the most striking and conclusive examples of the founder effect, right inside our cells. Thanks to mitochondrial DNA, we're now confident that we first became the modern human species we are today while still living in Africa, even if we picked up a little extra DNA here and there. But all this still left us pondering where specifically in Africa did our species first arrive on the scene. Africa is a huge continent after all. So how can we figure out where our species got its start? Well, we can start narrowing down our options by looking at the places where we find the oldest modern human fossils. And while that's a good starting point,
that probably won't be the way we get our answer on its own. For one, we can't guarantee we've even found the oldest modern human fossils yet, because they tend to be buried underground and hard to find. Another tricky consideration is that there could be a significant span of time between when our bodies were anatomically modern humans, and when our brains were. It's pretty tough to know when our behavior and problem-solving skills first appeared in a way that aligns with our current capabilities.
Clearly, narrowing down our species' original home base is no easy task, so we once again turn to DNA for help. While mitochondrial DNA provided the key evidence for our African origins, to narrow down the location, we need to look at entire genomes. We can compare DNA from living populations with DNA samples collected from ancient bones and tissues! If we want to find the oldest consecutive lineage of humans, we look for the people who are more genetically diverse than any other group on Earth. The most genetically diverse population of all modern humans that we know of are Khoe-San people, which is a group that includes the San hunter-gatherers and Khoekhoe pastoralist herders, both of whom mainly live in
South Africa, Namibia, Botswana, Angola, Zambia, Zimbabwe, and Lesotho. The term Khoe-San can be sort of controversial depending on who you ask, since it's kind of a catch-all for a few different ethnic groups. So for our purposes, we'll refer to the folks we're talking about as the Khoekhoe and San people. And their genetics tell quite the story. Their L0 mitochondrial DNA lineages are the oldest ones we've found in any living humans, and their chromosomal DNA is chock full of variation, too. So, since the Khoekhoe and the San people live in southern Africa, you might think we have the whole thing solved.
We must come from there! But there's a twist. See, they live in southern Africa today, but early studies of their mitochondrial DNA suggested they didn't necessarily start there. One study mapped migrations through Africa based on haplogroups, and found that the L0 haplogroup was found to have the highest diversity and highest frequency in southeast and east Africa. Given that highest variation often means earliest divergence, this suggested an eastern birthplace of modern humans. So for the umpteenth time we have to say there's more to the story.
Mitochondrial DNA works great to demonstrate our movement out of Africa, since we're only dealing with L3-derived haplogroups. But tracking movement using mitochondrial DNA is less clearcut within Africa when a lot of other ancient haplogroups are in play. Humans made pretty dramatic movements over the last few thousand years which spread and diversified the original L haplogroups across Africa, making it harder to trace their specific places of origin. So the mitochondrial diversity of eastern Africa might have been influenced by a lot more recent events than it first appears. And that's why it's important to look beyond just the mitochondrial DNA, a nd go all in on genome analysis.
Instead of just using DNA from African populations alive today, a study published in Nature in December 2025 sequenced whole genomes of 28 archaeological individuals from southern Africa, who were alive between 10,200 and 150 years ago. This technique helped to sort out what genetic material was a more recent addition to the gene pool, as even a relatively short jump back in time clears out a lot of modern-day gene swapping. And they realized that the ancient genomes had a ton of genetic variants that aren't around in humans today, even in the highly diverse genomes of the Khoekhoe and San peoples.
It would appear that these southern ancestors branched off f rom essentially all other human populations somewhere between 310 to 240 thousand years ago, back when we would have considered Homo sapiens to be in their early, and not modern stage. This southern African group also appeared to stay very isolated f rom other Homo sapiens populations for a long time. It's possible that environmental conditions were to blame, preventing their expansion beyond the southernmost region of Africa. But it clearly worked in their favor. The conditions they faced during that long period of isolation propelled them to perfect the modern human toolkit; complete with hearty immune systems, UV-protected skin, and upgraded kidneys.
Not only that, several of the gene variants unique to this ancient southern African population were tied to brain growth, neurons, and how the brain processes information. These specific adaptations would set this population apart not only from our Neanderthal and Denisovan cousins, but from the rest of our own species still living elsewhere in Africa. Eventually some of those immune-savvy brainiacs took their specialized gene pool north to join the rest of our Homo sapiens populations, likely in small-ish bursts over a longer period of time as milder conditions allowed them to leave the south.
Those genes ended up being so important to our species' survival, they would have infiltrated much of existing early human gene pools across Africa, spreading them to the broader human population. Some of these modern southern Africa humans likely stayed closer to home in the south, which explains why the ancestors of the Khoekhoe and San peoples have retained a lot more of our original genetic variation. So today's Khoekhoe and San peoples might still be the closest tie to our southern African start, despite having lost around 20% of their ancient ancestors' DNA over the last few centuries. Of course, these DNA results and hypothetical models
still leave us with a very inconclusive origin story overall. That said, it appears that southern Africa could be the location that really pushed us to become our modern human selves: anatomically, behaviorally, and genetically. While we still don't have a definitive answer for exactly where in Africa we originated, the more we look into our own DNA, the more we reveal about ourselves. It can not only help us figure out the wheres and whens, but also reveal really interesting aspects of our history, like what were some of the specific conditions and pressures we faced to evolve our immensely useful brains.
One thing is certain, we humans covered a lot of ground from the very beginning. So if you're a wandering soul, you've got that in common with the very earliest members of our species. [OUTRO]
