We humans are famously adaptive.

We’ve lived, and still live, in pretty wildly diverse environments across the globe. And some of the places we  call home have a lot harsher conditions than others, like the  frozen tundra or dry deserts.

But the Turkana people of northern  Kenya might have us all beat. They live under some of the harshest  conditions of anyone anywhere – so harsh that a group of  researchers worked together with their community to find out how they do it. And their results tell us not only about this one specific community and how they live.

They might also tell us about  everyone and how we adapt to new lifestyles, helping us understand  heart disease, diabetes, and more. [♪INTRO] A lot of the ways humans adapt to  new environments are behavioral, like what we wear and what our homes are like. Other adaptations are a lot less obvious, and may be hidden in our genes. Even though we know humans aren’t  immune to natural selection, we have surprisingly little data on the different ways we’ve adapted to specific environments.

Research published in the journal Science in 2025 set out to help us learn more. The study focused on the Turkana people. Today they mostly live in northwest  Kenya, which happens to be one of the most arid, hostile places  people are known to currently live.

But despite the seemingly harsh conditions, most Turkana have kept up the same lifestyle their ancestors have been following  for thousands of years. This extremely dry desert region  is not exactly an ideal location to hunt or harvest your food,  let alone grow your own crops. Instead, the Turkana are nomadic pastoralists.

This means they raise livestock,  but they aren’t keeping them in one place year round.  Instead, they move around to where the conditions are  the best for that time of year. Essentially they follow rainfall, and the vegetation growth that comes along with it. Most of that vegetation isn’t directly  eaten by the Turkana themselves, but rather feeds their goats, sheep, and camels.

And that’s where their diet is really interesting. They rely on their livestock for a  huge portion of their dietary needs. Between 70 to 80 percent of their diet is from animal products including meat, milk, and blood.

So, if you are thinking that sounds  like a lot of protein, you are correct. Like, a lot a lot. About 300 percent more than the World Health Organization’s  recommended daily intake, enough to cause significant worries about  clogged arteries in most people.

The Turkana are also extremely  unlikely to be meeting your average daily recommended intake of water. Rainfall is rare and short-lived, so even though they’re consuming liquid-heavy  foods in blood and milk, they still spend several hours a day walking great distances to collect water in the  hot, dry, and exposed conditions. This would be a significant  physical challenge for many people regardless of fitness level, but  the Turkana take it in stride.

And this realization is what  sparked this research question to begin with! We sat down with Julien Ayroles, a member of the team  responsible for this research. The project happened almost serendipitously.

I was hiking in Turkana County with  a friend of mine who is Kenyan. And we're hiking, I was completely  dehydrated and we came across these three ladies with, you  know, bucket of water on the head, babies strapped on the chest.  And, I was absolutely bewildered. You couldn't see any housing in sight.

And so ask my friend, like, what's going on? How are you doing this? He's like, oh, they're  Turkana.

That's what they do. They walk three to six miles to  get water on a very regular basis. And so as we're walking back to the car, we're sort of wondering how how did this happen?

What is the biology allowing  such an incredible set of skills. While these long walks for  water are extremely impressive, they’re not exactly carrying home  an abundance of the wet stuff. And when they were asked  about their water situation, the Turkana study participants nearly unanimously recognized they don’t have access to enough.

Their physical test results back that up too, revealing that almost 90% of Turkana people tested met the criteria for dehydration. While it might seem like a big risk  to your health to be chronically dehydrated while eating 300% more  protein than a lot of the human population, it’s not the recipe for  a health disaster it sounds like. That is, if your genes have adapted  to those very specific conditions.

And in the case of the Turkana, they have. For this study, the genomes  of 308 Turkana participants were sequenced, as well as an additional 59 people from other communities in the region. From there, they compared this sequenced DNA to known data sets of populations  from other regions of Africa.

And the analysis found a  number of regions of their DNA that stood out from the pack, but  one region in particular really seemed to be strongly selected  for in the Turkana population. This region appeared to be an enhancer: a handy bit of DNA that boosts  the transcription of a gene, meaning how much it’s getting used by the cell. And the boosted gene in this case is called STC1.

In earlier studies, STC1 has been  tied to the removal of some of the waste products made as  our body breaks down purines, compounds that just so happen to  exist in high concentrations in meat. Purines are something you can  definitely have too much of, leading to potentially  dangerous conditions like gout. STC1 also appears to play a  role in concentrating urine, which is extremely helpful when your body is trying to use water as efficiently as possible.

So STC1 definitely seems like a  gene you'd want to have in abundance if you live in the desert with little  water and a lot of meat to eat. What’s extra cool about  comparing these large sets of DNA across regions is that you can  uncover when specific genes started to be strongly selected  for in a population’s history. And in the case of this STC1 boosting region, it began making its mark  nearly 350 generations ago.

And what was happening around  that time in East Africa? The climate was becoming very, very dry! One, we uncovered the footprint  of selection and we actually could tie it back to the timing  of selection when the Turkana moved from the where they were 5,000  years ago all the way up north, more or less where Egypt is today.

And they migrated southward as Africa became, the north part of Africa became the Sahara where the people moved southward. And so the timing of selection  coincided well with that. So the aridification of northern part of Africa.

Not only did this genetic  comparison study start to uncover how Turkana genes could be  specifically tuned to work to their advantage under  seemingly extreme environments. The study also shed light on how  natural selection under a changing climate could have very likely led  to these vital genetic adaptations, which are still doing their  thing hundreds of generations, and thousands of years, later. But there’s even more we  can learn from all of this, and it might take us well beyond the desert!

But first, we’ll keep the  lights on with this quick break. Thanks for watching this SciShow video! And thanks for watching any of our videos that have come out over the last 14 years!

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Check out the links below  to support us. Thank you! Even though many Turkana still practice their traditional nomadic lifestyle, others have stuck to living rurally but no longer really following their  traditional pastoral practices.

Still others have moved away from the open desert entirely, and into urban environments. Moving from the pastoral plains  to a more urban area would grant you much easier access to lots of diverse foods, and enough water to stave off  near-constant dehydration. Must be all good, right?

Well, not necessarily. And this brings us to the  evolutionary mismatch hypothesis. This is a fairly intuitive idea.

It says that if you pluck an organism out of the conditions it’s adapted to,  it’s going to have a bad time. Essentially, leaving those friendly conditions could be detrimental to our health. Even if the new conditions, especially  for those of us in the global North, seem like they should be  easier to thrive under, not harder.

I did not evolve to sit around typing on a keyboard most of the day, but here I am. But while this mismatch idea  has been around for a while, there’s still not a whole lot  of clear data to back it up, genetically speaking. That’s largely because in many populations, our current lifestyles and  conditions have been different from our ancestors for quite some time now, so making a direct comparison is pretty tricky.

Most of the time the comparisons have been between European populations and say hunter gatherers, and when you compare a European population to a hunter-gatherer group, the timing of the transition is very different, right? Europeans have transitioned to a non-subsistent, you know, we've been markedly  integrated for a very long time. And of course the genetics is very different.

Even though these distinct population  comparisons are less than ideal, the mismatch theory hypothesis is  still sometimes invoked to explain why certain ailments, like  heart disease and diabetes, are problems in urban societies. And thanks to the specific  lifestyle and geographic history of the Turkana, they're set up for a much cleaner comparison between populations. So what makes the Turkana community an amazing partner in this project is  that within an ancestry group, we have a lifestyle gradient  where some people live traditional lifestyle up north, right?

All the way up north in Kenya. And if you as you move further south, people are, you know, some people live like you and I, we’re in an air-conditioned room and eating the same kind of food probably. The study had the ability to  compare a population that has made a pretty rapid shift from  one environment to another.

And that allowed the team to see  some patterns a bit more clearly. They noticed that urban Turkana  had changes to metabolism and gene expression compared  to pastoral individuals. This suggests that their  bodies were reacting to changes in the environmental conditions they were facing.

Essentially, their new lifestyle  might not be jiving well with their old genes, and  their internal processes were being tweaked in response to make up for it. For Turkana people living  in these urban conditions, their shifting gene activity  highlighted a potential increased risk of chronic  diseases like heart disease. And this is significant, because these are diseases that are pretty new to the Turkana.

And noticing along the way  that many of the diseases that are so common in the  the West, broadly speaking, that were very rare in the  Turkana community became more and more common as they  transition to an urban lifestyle. And one of the leading hypotheses  globally, and not just for the talk about why is it that 100 years  ago, most people died of infectious disease, and now we die of  non-communicable disease as a species. So this line of research  could help us learn even more about health problems that are linked to lifestyle changes in urban settings across the world.

The people who stand to  benefit most from the answers to all these questions are the Turkana themselves. But that may not be /too/ surprising, because it’s the Turkana who asked them in the first place. Thanks to the partnership model  used to conduct the research, the Turkana community has been  directly involved in deciding the kind of information they want to learn  about themselves through the project.

People are sort of seated in a circle  and for about a day, we just like, it's a question, it's a  rapid firing of of questions and when we can provide some answers and sometimes we just like make a note, like,  oh, that would be interesting. We should ask that question as well. And some of the questions we're  asking today about parasites and about water quality and many other  things along those lines came from people and the during this sit  down meeting, asking the questions.

And then we do our best to return results. And then we bring results back. We get more questions and then  that sort of feeds the cycle.

I should also say that the  project team is about 12 people, all Kenyans and half of  them are Turkana themselves. So there's integration at that level as well. As a result of these community  discussions, around 5,000 people across 80 communities have enrolled  in the research cohort so far.

With so many participants across  these communities, it makes for a lot of people to report back to as well,  which is a vital part of the project. But sharing back the results to  a community that is spread across this huge region, partially nomadic,  and unlikely to be able to read the findings in a paper published in English  even if you could get it to them, poses a significant challenge. So the researchers are creating a podcast in the Turkana language to better share  the results with the community.

This project is not only helpful for the Turkana who are living through these  changes in real time though. It’s helping us discover the  different ways human health is intertwined with our environment, our genetics, and how our ancestors used to live. Learning what conditions our genes  are best adapted to withstand, and what ones cause us grief,  could benefit a lot of people, whether you’re a pastoral nomad  or a work-from-home urbanite.

Through that knowledge, maybe  we can start to decrease the rate of some diseases  associated with the mismatch between what our ancestors were doing and eating, versus what our days, and dinners, look like now. [♪OUTRO]