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How to Live in the Harshest Place on Earth
How to Live in the Harshest Place on Earth
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자막 (270)
0:00
We humans are famously adaptive.
0:02
We’ve lived, and still live, in pretty wildly
0:05
diverse environments across the globe.
0:07
And some of the places we call home have a lot harsher
0:10
conditions than others, like the frozen tundra or dry deserts.
0:13
But the Turkana people of northern Kenya might have us all beat.
0:17
They live under some of the harshest conditions of anyone anywhere –
0:21
so harsh that a group of researchers worked together
0:24
with their community to find out how they do it.
0:26
And their results tell us not only about
0:28
this one specific community and how they live.
0:30
They might also tell us about everyone and how we adapt to new
0:35
lifestyles, helping us understand heart disease, diabetes, and more.
0:41
[♪INTRO]
0:43
A lot of the ways humans adapt to new environments are behavioral,
0:46
like what we wear and what our homes are like.
0:49
Other adaptations are a lot less obvious,
0:52
and may be hidden in our genes.
0:53
Even though we know humans aren’t immune to natural selection,
0:57
we have surprisingly little data on the different
0:59
ways we’ve adapted to specific environments.
1:02
Research published in the journal Science
1:04
in 2025 set out to help us learn more.
1:06
The study focused on the Turkana people.
1:08
Today they mostly live in northwest Kenya, which happens to be
1:12
one of the most arid, hostile places people are known to currently live.
1:16
But despite the seemingly harsh conditions,
1:18
most Turkana have kept up the same lifestyle their
1:21
ancestors have been following for thousands of years.
1:24
This extremely dry desert region is not exactly an ideal location
1:28
to hunt or harvest your food, let alone grow your own crops.
1:32
Instead, the Turkana are nomadic pastoralists.
1:35
This means they raise livestock, but they aren’t keeping
1:37
them in one place year round. Instead, they move around
1:40
to where the conditions are the best for that time of year.
1:43
Essentially they follow rainfall, and the
1:45
vegetation growth that comes along with it.
1:47
Most of that vegetation isn’t directly eaten by the Turkana themselves,
1:50
but rather feeds their goats, sheep, and camels.
1:53
And that’s where their diet is really interesting.
1:56
They rely on their livestock for a huge portion of their dietary needs.
2:00
Between 70 to 80 percent of their diet is from
2:03
animal products including meat, milk, and blood.
2:05
So, if you are thinking that sounds like a lot of protein, you are correct.
2:09
Like, a lot a lot. About 300 percent more than the
2:13
World Health Organization’s recommended daily intake, enough to
2:16
cause significant worries about clogged arteries in most people.
2:20
The Turkana are also extremely unlikely to be meeting
2:23
your average daily recommended intake of water.
2:26
Rainfall is rare and short-lived, so even though
2:29
they’re consuming liquid-heavy foods in blood and milk,
2:32
they still spend several hours a day walking great
2:35
distances to collect water in the hot, dry, and exposed conditions.
2:40
This would be a significant physical challenge for many people
2:43
regardless of fitness level, but the Turkana take it in stride.
2:46
And this realization is what sparked this research question to
2:49
begin with! We sat down with Julien Ayroles,
2:53
a member of the team responsible for this research.
2:54
The project happened almost serendipitously.
2:57
I was hiking in Turkana County with a friend of mine who is Kenyan.
3:01
And we're hiking, I was completely dehydrated and we came across
3:04
these three ladies with, you know, bucket of water on the head,
3:08
babies strapped on the chest. And, I was absolutely bewildered.
3:12
You couldn't see any housing in sight.
3:14
And so ask my friend, like, what's going on?
3:17
How are you doing this?
3:17
He's like, oh, they're Turkana. That's what they do.
3:20
They walk three to six miles to get water on a very regular basis.
3:24
And so as we're walking back to the car,
3:25
we're sort of wondering how how did this happen?
3:28
What is the biology allowing such an incredible set of skills.
3:35
While these long walks for water are extremely impressive,
3:38
they’re not exactly carrying home an abundance of the wet stuff.
3:41
And when they were asked about their water situation,
3:43
the Turkana study participants nearly unanimously
3:46
recognized they don’t have access to enough.
3:49
Their physical test results back that up too,
3:51
revealing that almost 90% of Turkana people
3:54
tested met the criteria for dehydration.
3:56
While it might seem like a big risk to your health to be chronically
4:00
dehydrated while eating 300% more protein than a lot of the human
4:04
population, it’s not the recipe for a health disaster it sounds like.
4:08
That is, if your genes have adapted to those very specific conditions.
4:12
And in the case of the Turkana, they have.
4:14
For this study, the genomes of 308 Turkana participants
4:18
were sequenced, as well as an additional
4:20
59 people from other communities in the region.
4:22
From there, they compared this sequenced DNA
4:24
to known data sets of populations from other regions of Africa.
4:28
And the analysis found a number of regions of their DNA
4:31
that stood out from the pack, but one region in particular really
4:35
seemed to be strongly selected for in the Turkana population.
4:38
This region appeared to be an enhancer:
4:40
a handy bit of DNA that boosts the transcription of a gene,
4:44
meaning how much it’s getting used by the cell.
4:46
And the boosted gene in this case is called STC1.
4:50
In earlier studies, STC1 has been tied to the removal of some of
4:54
the waste products made as our body breaks down purines,
4:58
compounds that just so happen to exist in high concentrations in meat.
5:02
Purines are something you can definitely have too much of,
5:05
leading to potentially dangerous conditions like gout.
5:08
STC1 also appears to play a role in concentrating urine,
5:12
which is extremely helpful when your body is
5:14
trying to use water as efficiently as possible.
5:16
So STC1 definitely seems like a gene you'd want to have in abundance
5:20
if you live in the desert with little water and a lot of meat to eat.
5:24
What’s extra cool about comparing these large sets of DNA
5:27
across regions is that you can uncover when specific genes
5:31
started to be strongly selected for in a population’s history.
5:35
And in the case of this STC1 boosting region,
5:38
it began making its mark nearly 350 generations ago.
5:41
And what was happening around that time in East Africa?
5:44
The climate was becoming very, very dry!
5:47
One, we uncovered the footprint of selection and we actually
5:50
could tie it back to the timing of selection when the Turkana
5:54
moved from the where they were 5,000 years ago all the way up north,
5:58
more or less where Egypt is today.
5:59
And they migrated southward as Africa became,
6:03
the north part of Africa became the Sahara
6:04
where the people moved southward.
6:06
And so the timing of selection coincided well with that.
6:09
So the aridification of northern part of Africa.
6:11
Not only did this genetic comparison study start to uncover
6:14
how Turkana genes could be specifically tuned to work to
6:18
their advantage under seemingly extreme environments.
6:21
The study also shed light on how natural selection under a changing
6:25
climate could have very likely led to these vital genetic adaptations,
6:29
which are still doing their thing hundreds of generations,
6:32
and thousands of years, later.
6:34
But there’s even more we can learn from all of this,
6:36
and it might take us well beyond the desert!
6:38
But first, we’ll keep the lights on with this quick break.
6:41
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6:43
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6:45
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6:47
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7:16
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7:19
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7:23
Even though many Turkana still practice
7:25
their traditional nomadic lifestyle,
7:27
others have stuck to living rurally but no longer
7:30
really following their traditional pastoral practices.
7:33
Still others have moved away from the open
7:35
desert entirely, and into urban environments.
7:37
Moving from the pastoral plains to a more urban area would grant
7:41
you much easier access to lots of diverse foods,
7:44
and enough water to stave off near-constant dehydration.
7:48
Must be all good, right?
7:50
Well, not necessarily.
7:51
And this brings us to the evolutionary mismatch hypothesis.
7:55
This is a fairly intuitive idea.
7:56
It says that if you pluck an organism out of the
7:59
conditions it’s adapted to, it’s going to have a bad time.
8:02
Essentially, leaving those friendly conditions
8:04
could be detrimental to our health.
8:06
Even if the new conditions, especially for those of us in the global
8:09
North, seem like they should be easier to thrive under, not harder.
8:13
I did not evolve to sit around typing
8:14
on a keyboard most of the day, but here I am.
8:17
But while this mismatch idea has been around for a while,
8:20
there’s still not a whole lot of clear data to back it up,
8:24
genetically speaking.
8:25
That’s largely because in many populations,
8:27
our current lifestyles and conditions have been different
8:29
from our ancestors for quite some time now,
8:32
so making a direct comparison is pretty tricky.
8:34
Most of the time the comparisons have been between
8:36
European populations and say hunter gatherers,
8:40
and when you compare a European population
8:43
to a hunter-gatherer group, the timing of
8:46
the transition is very different, right?
8:48
Europeans have transitioned to a non-subsistent,
8:50
you know, we've been markedly integrated for a very long time.
8:53
And of course the genetics is very different.
8:55
Even though these distinct population comparisons are less than ideal,
8:58
the mismatch theory hypothesis is still sometimes invoked to explain
9:01
why certain ailments, like heart disease and diabetes,
9:04
are problems in urban societies.
9:06
And thanks to the specific lifestyle and geographic
9:09
history of the Turkana, they're set up for
9:11
a much cleaner comparison between populations.
9:14
So what makes the Turkana community an amazing
9:18
partner in this project is that within an ancestry group,
9:22
we have a lifestyle gradient where some people live
9:25
traditional lifestyle up north, right?
9:27
All the way up north in Kenya.
9:29
And if you as you move further south, people are,
9:31
you know, some people live like you and I,
9:33
we’re in an air-conditioned room and
9:35
eating the same kind of food probably.
9:37
The study had the ability to compare a population that has
9:40
made a pretty rapid shift from one environment to another.
9:43
And that allowed the team to see some patterns a bit more clearly.
9:47
They noticed that urban Turkana had changes to metabolism
9:50
and gene expression compared to pastoral individuals.
9:53
This suggests that their bodies were reacting to changes
9:55
in the environmental conditions they were facing.
9:58
Essentially, their new lifestyle might not be jiving well
10:01
with their old genes, and their internal processes were
10:04
being tweaked in response to make up for it.
10:06
For Turkana people living in these urban conditions,
10:09
their shifting gene activity highlighted a potential
10:12
increased risk of chronic diseases like heart disease.
10:15
And this is significant, because these are
10:17
diseases that are pretty new to the Turkana.
10:19
And noticing along the way that many of the diseases
10:22
that are so common in the the West, broadly speaking,
10:26
that were very rare in the Turkana community became
10:29
more and more common as they transition to an urban lifestyle.
10:34
And one of the leading hypotheses globally, and not just for the talk
10:38
about why is it that 100 years ago, most people died of infectious
10:41
disease, and now we die of non-communicable disease as a species.
10:45
So this line of research could help us learn even more
10:47
about health problems that are linked to lifestyle
10:50
changes in urban settings across the world.
10:52
The people who stand to benefit most from the answers
10:54
to all these questions are the Turkana themselves.
10:57
But that may not be /too/ surprising, because it’s
10:59
the Turkana who asked them in the first place.
11:01
Thanks to the partnership model used to conduct the research,
11:04
the Turkana community has been directly involved in deciding the kind
11:07
of information they want to learn about themselves through the project.
11:11
People are sort of seated in a circle and for about a day, we just like,
11:15
it's a question, it's a rapid firing of of questions
11:19
and when we can provide some answers and sometimes
11:21
we just like make a note, like, oh, that would be interesting.
11:23
We should ask that question as well.
11:25
And some of the questions we're asking today about parasites and
11:28
about water quality and many other things along those lines came from
11:33
people and the during this sit down meeting, asking the questions.
11:37
And then we do our best to return results.
11:40
And then we bring results back.
11:42
We get more questions and then that sort of feeds the cycle.
11:46
I should also say that the project team is about 12 people,
11:49
all Kenyans and half of them are Turkana themselves.
11:52
So there's integration at that level as well.
11:55
As a result of these community discussions, around 5,000 people
11:58
across 80 communities have enrolled in the research cohort so far.
12:02
With so many participants across these communities, it makes for a lot
12:06
of people to report back to as well, which is a vital part of the project.
12:10
But sharing back the results to a community that is spread across
12:13
this huge region, partially nomadic, and unlikely to be able to read the
12:17
findings in a paper published in English even if you could get it to them,
12:22
poses a significant challenge.
12:23
So the researchers are creating a podcast in the
12:25
Turkana language to better share the results with the community.
12:28
This project is not only helpful for the Turkana
12:30
who are living through these changes in real time though.
12:33
It’s helping us discover the different ways human health is
12:36
intertwined with our environment, our genetics,
12:38
and how our ancestors used to live.
12:40
Learning what conditions our genes are best adapted to withstand,
12:44
and what ones cause us grief, could benefit a lot of people,
12:47
whether you’re a pastoral nomad or a work-from-home urbanite.
12:50
Through that knowledge, maybe we can start to decrease
12:52
the rate of some diseases associated with the mismatch between
12:56
what our ancestors were doing and eating,
12:58
versus what our days, and dinners, look like now.
13:07
[♪OUTRO]
