How People Have Evolved to Live in the Clouds

How People Have Evolved to Live in the Clouds

Thanks to Brilliant for supporting this episode
of SciShow. Go to to learn more. ♪♪♪ Even the most seasoned mountain climbers can
start to struggle at high altitudes. That’s because the higher you hike, the
thinner the air gets. It’s literally less dense because it’s
under less pressure, and that means you get fewer oxygen molecules from every breath. And since oxygen is kind of important for
us, humans run into all sorts of problems at high elevations. But there are millions of people around the world who spend their whole lives thousands of meters above sea level and seem to have little to no trouble with the oxygen levels. Their secret: their bodies are more efficient
at operating in low-oxygen environments thanks to special tweaks to their physiology. And those differences are passed down from
generation to generation—making them a great example of human evolution. We need oxygen because it’s one of the major
building blocks in biological molecules. It’s involved in countless important reactions
in our bodies, including the ones that allow us to use sugars as cellular fuel. And because of that, being low on oxygen means
struggling with physical activities that are normally easy. It can also cause all sorts of uncomfortable
side effects, like headaches, nausea, and sleeplessness. And, of course, if there’s not enough oxygen,
you can’t survive at all. The technical term for having too little oxygen
in your tissues is hypoxia. And there’s nothing special about the hypoxia
people experience at high altitudes, it’s just that when hypoxia comes from being at
high elevations, we call it altitude sickness or mountain sickness. To combat it, experienced mountain climbers
usually ascend slowly. That gives their bodies time to acclimatize
to the new conditions. You see, if you spend enough time at a high
altitude, you’ll find your body automatically adjusts to get more oxygen adjustments which
disappear once you return to lower elevations. Your body will produce more red blood cells,
for example, which carry oxygen around, allowing you to absorb more from the air in your lungs. You’ll also breathe more rapidly so you
take in more fresh air. And there are less obvious changes that happen
within your cells. But such changes aren’t cheap. Ironically, to survive when there’s less
oxygen, your body increases your metabolism by as much as 27% for the first few weeks, meaning you need more oxygen than usual during that time. Not every person at high altitudes has this
increase in metabolic rate, though. Like, the people who are indigenous to the
Andes mountains in South America, for example. And that’s because their low oxygen-coping mechanisms aren’t temporary. They’re long-term adaptations. People have lived in the Andes for at least
11,000 years, and in that time, they’ve evolved to survive in a low-oxygen environment. We’re talking human populations that exist
3500 meters or more above sea level, where oxygen levels are only around 60% of what
we’re used to at lower elevations. Andeans produce more red blood cells so they
can pack more oxygen-carrying hemoglobin into their blood. They also have more of those hemoglobin molecules
bound to oxygen at any given time—a measure known as oxygen saturation. That way, they can get enough oxygen to their
tissues without needing to increase their metabolism or breathing rate. It’s an incredible example of how evolution
has allowed humans to survive in extreme conditions, but it comes with risks. Cramming more blood cells into your veins
and arteries can increase the chances of clotting. And clots can jam up the circulatory pipes
to cause strokes and heart attacks. So the people from the Tibetan Plateau in
Asia have a different approach to the oxygen problem. Millions of Tibetans live and work at an average
elevation of 4,000 meters above sea level, and there have been settlements there for
an astounding 25,000 years. Like with Andeans, Tibetan ancestry comes
with some physiological perks which help them survive and operate in the oxygen-poor air. But they don’t have more hemoglobin. In fact, they have special mutations that
limit the production of hemoglobin to make sure of that! They do breathe more rapidly—much like people
do when they acclimatize to high elevations. But Tibetans have combined their high breathing
rate with another trick. They also produce higher-than-normal levels
of nitric oxide, a chemical which plays a part in vasodilation, the widening of blood
vessels, so their blood can flow more easily. And that’s because their strategy is all
about boosting circulation. Faster breaths and smoother blood flow allows
Tibetans to deliver the oxygen from their lungs to their tissues quickly and efficiently. So they can get enough oxygen without needing
more red blood cells. And just like Andean populations, these are
heritable traits. Tibetan babies come into the world better
equipped to breathe thin air, even when they’re born at low elevations. But there’s a lot more to living in such
high places than we currently understand. Genetic research has revealed that high-elevation
populations have all sorts of unique mutations in their genomes that have little or nothing
to do with oxygen. Like, Tibetan people have mutations in genes
associated with higher body weight and body fat. Life can be pretty tough high up on the plateau,
with the harsh weather and a lot of seasonal variation in nutrition. So these mutations may help them store energy
better during tough times. Interestingly, they also show mutations to
genes which boost the production of a vitamin called folate. Folate is broken down by ultraviolet radiation,
which is more intense at higher elevations, so this might be important for maintaining
normal vitamin levels up on the plateau. And some high-altitude adaptations remain
mysterious! The people of the Ethiopian plateau in Africa
survive just fine without basically any of the physiological tweaks we see in Tibetans
or Andeans. How they do that is still unclear. But, the fact that high-altitude adaptations
have evolved at least three separate times in populations from around the world is a
clear case of convergent evolution. And it’s not just seen in humans. Just like the people of Tibet, Tibetan mastiffs
have tweaks in a hemoglobin-regulating gene called EPAS1, which helps keep the dogs’
blood from getting too thick. These adaptations, arising over and over again,
are part of the fascinating evolutionary story that has allowed us humans — and our pets
— to thrive in some of the most extreme environments on Earth. While we’ve known about high-elevation adaptations
for decades, it wasn’t until recently that scientists could peer into people’s genomes
to begin to figure out how those adaptations took place. And if you want to better understand how they
did that, you might like the courses being offered by Brilliant has interactive courses that cover
all sorts of science, math, engineering, and computer science topics. And their course on Computational Biology
can help you make sense of genomics research. You see, to understand what has happened to
people’s genomes, scientists have to examine huge amounts of genetic data. Brilliant’s course dives deep into the computer
science behind genomics to explain how things like techniques like DNA profiling and ancestry
analysis actually work. And, you can take your learning on the go,
because Brilliant’s iOS app now has an offline mode for their in-depth courses. The first 200 people to sign up at
will get 20% off an annual Premium subscription. And you’ll not only save money, you’ll
be helping support SciShow. ♪♪♪

100 Replies to “How People Have Evolved to Live in the Clouds”

  1. Go to to try their Computational Biology course. The first 200 subscribers get 20% off an annual Premium subscription.

  2. And guess what, the dogs are still dogs and the humans are still humans. That's adaptation, not evolution.

  3. this reminds me of the videos I have seen of the people who have adapted to holding their breath underwater to walk on the ocean floor and go spearfishing for a lengthy amount of time …

  4. You can pop a viagra if you need a short term solution say for a day trip up Kawa Ijen.
    Don't take a normal dose of Dexamphetamines like I did (I have ADHD and am 55)
    Nitric Oxiide sounds like a winner. Great video #SciShow

  5. My hometown is 2300 meters above sea level, we have fresh air all the year, and because of the altitude, temperatures don't rise more that 31 Celsius in summer, we have great weather, now I'm living at just 300 or less meters from the sea level, in contrast I find difficult to breath well and struggle when the summer becomes extreme heat and high humidity

  6. so can we cross breed andeans and tibetans and see the result? maybe we can get some ethiopians in the mix?

  7. Hi Sci show people
    why don't you meet a video about that man, Mr. Apa Sherpa, who climbed the Everest 21 times and also also his tribe the Mighty shabaz

  8. I think you mix up adaptation with evolution. Evolution is when you change from a rock to a living cell, and adaptation is changes you body make to survive better.

  9. So those people had the luck to be naturally selected to use oxygen more efficiently, and those people just happened to already live in high altitudes? What a coincidence. Interesting how natural selection does that. What are epigenetics?

  10. Isn't this the photo of a village🏚 of Nepal?
    Land of Mt. Everest 🏔🌫🌦
    And my nation as well.🤓😀❤

  11. I would be curious what the results would be if the various high elevation populations were to mix and, ultimately, have children

  12. Interesting stuff… Also proving Race is real and that Tibetans and Andeans are SUPERIOR to us at living at high altitudes.

    I know such a terrible reality we're living in… People with heritable adaptations that actually innately make them better at some specific things. *THE HORROR!!!*

  13. Now I wanna know how the adaptations interact.
    Like Andean-Tibetan babies.. how's their adaptation level, do they add up, cancel the negative side effects? Multiply other side effects?

  14. SciShow
    Did You just say 35 Hundred Meters ?!…
    Please don't use BS (Units or) Numbering Conventions on a Science Channel
    Just say it normally as "3 Thousand 5 Hundred Metres"

    Never saw a Science Guy use a conversion equivalent to 35×10² m before…
    Normally in Science one would say that either in 3.5×10³ m , 3.5 km , or Literally 3500 m as the Number is still not that big…

    in Summary (AKA "TL;DR"):
    – Saying it as "35 Hundred" is Both against Science Norms and is a show of One's Speaking Laziness (just to skip the word "Thousands")…

    C Ya L8r then!. ;P

  15. Interesting. It would seem there must be some "environmental factor" favoring widened blood vessels and faster breathing over hemeglobin enhancements, seeing as the traits are shared by two genetically unrelated species (humans and canines). Oddly it would seem widened blood vessels would be helpful for having a higher hemeglobin density, and yet we don't see those traits together so it makes sense to me that the hemeglobin inhibition was the first trait to evolve, probably due to the "environmental factor," and widened blood vessels was the response as an alternate adaption to the climate. It's a shame, seems we should figure out how to combine these traits for everyone.

    But the curious thing is this, since it makes sense to me that if widened blood vessels evolved first there would be little benefit to a hemeglobin inhibitory effect (and at altitude it may even be a detriment), it would be unlikely to see the inhibitory trait develop later. Thus I wonder what that "environmental factor" was. It would be something those two closely mingled but genetically distinct species, man and dog, share. Maybe something in the food?

  16. I wonder how they fair when these people go down to low elevations long and short terms. Also I wonder how the blood pressure of these people are with he vasodilation and increased blood flow.

  17. Anyone here notice how all these science/information channels seemingly rip each other off?

    Too many times has a video somewhere told me an interesting fact(s), and then a few days later, there's like a new sci-show channel based around those facts. Not mad… Just anyone noticed this?

  18. Maybe the climate in Tibet is different enough that the people their didn't have to compensate as much? (Like 'warmer' weather or higher humidity allowing for more diverse Flora and fauna? And thusly more oxygen?)

  19. Has anyone noticed the number of climbers dying this week, many coming down from Mt. Everest. Apparently there has developed a climber traffic jam of sorts, with people just barely able to squeeze by each other on the ridge path leading to the summit. Since every one is going even slower than normal, some just aren't making it, including very experienced climbers. Why is there no limit to the number allowed on the peak?

  20. We studied this in one of our anthropology courses. The Andes people are adapted, but not quite evolved yet, as per say the Sherpa in the Himalayas. The key giveaway to this is giving live birth at high elevations or not. A study showed that Andes women would return to lower elevations for easy birth and giving the child a chance to live. The Sherpa women did not have to do the same. Their babies would live. Adaptation verses evolution scenario.

  21. Anyone else wondering what would happen is someone from the andes and tiben had a kid together? Or a group of them? or after a few generation? I am curious. I wonder which adaptations would they get and which ones would be dominant over generations. Sadly we will likely never know.

  22. But this doesn't apply to IQ or even just more specific reasoning and temperament traits? These only took 11,000 years…

  23. What have they evolved into you freakin idiot. They are still human and cannot change into anything else. It’s called variation in the species not evolution. It’s the opposite of evolution

  24. wait – did you just say the dog adaptations were similar to those of the human population of the same geographic area?

    are there other examples of similar cross species adaptations for a given area?

    and what is it about these different geographic areas that seem to be driving different adaptations?


  25. What about the “barrel-chested” adaptations made by people living in higher altitudes? Is that also specific to peoples in those regions?

  26. Andean women go to lower elevations late in pregnancy to increase the survival chances of the baby. A couple of months after delivery, they ascend back up. Usually neither the woman nor baby has any problems.

  27. So to bring it back to the USA instead of Ethiopia, so to speak, are there any changes in the inhabitants of Denver CO?

  28. The content is always good – but it's the presenter that makes these videos great. Thanks, Michael Aranda!

  29. I have heard that bigger lung capacity (being barrel chested) and shorter limbs are adaptations for Andean populations to help with poorer oxygen that true?

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