Adaptation to high-altitude hypoxia on the Tibetan Plateau
79 comments
·October 22, 2024yard2010
Interestingly enough, the source[0] comparing the andean evolution and the tibetan evolution which are a bit different - which makes this a case of convergent evolution.
TIL the human body for the last billion years does not store oxygen in the mitochondria, despite the wide swings in the oxygen levels in the atmosphere, probably due to its destructive effects. In other words: the air is toxic. We breathe it enough, we die.
echelon
> the air is toxic.
Oxygen is the oxadative species that drives our biochemistry. It's a fuel.
Oxygen is highly reactive. It is a fantastic evolutionary gradient as it has tons of free and readily available energy to harness. But of course it's also what also wears us down by putting oxidative stress on our cells, DNA, and molecular biology. It causes all sorts of damage as a byproduct of what it is.
Oxygen is life and death.
The particulates suspended in the air are yet another problem ...
thaumasiotes
> the andean evolution and the tibetan evolution which are a bit different - which makes this a case of convergent evolution.
Only in function; they're very different in form. The Tibetan suite of adaptations uses more efficient hemoglobin; the Andean suite uses larger amounts of hemoglobin.
This is generally explained as reflecting the much, much, much, much greater age of the Tibetan suite.
There is a third standard example of a suite of high-altitude adaptations in humans, found in Ethiopian highlanders. For whatever reason, it sees almost 100% less discussion.
o11c
> third standard example
Probably because people don't think of Africa as having much extended elevation. And by-and-large, the continent is pretty flat (only Australia and Europe-ignoring-the-Alps are flatter).
It's very difficult to find (or even define) a list of non-mountain high points in the world, but "average elevation of country" (which is only unreasonable for a handful of the largest countries) is easier to find, and Ethiopia is only around 19th place in such lists (17th if we exclude Greenland and Antarctica which are not actually countries), not even the highest in Africa.
blackeyeblitzar
> We breathe it enough, we die.
Isn’t this true of anything in excess? For gases - nitrogen, oxygen, carbon dioxide, etc all have this effect. In fact some states are using nitrogen for executions, although it’s not exactly humane (warning: https://en.wikipedia.org/wiki/Execution_of_Kenneth_Eugene_Sm...).
thaumasiotes
> gases - nitrogen, oxygen, carbon dioxide, etc all have this effect
What effect are you talking about? Those gases all have very different, unrelated effects.
> In fact some states are using nitrogen for executions
The nitrogen isn't harmful; the cause of death is the amount of oxygen (zero), not the amount of nitrogen (slightly more than normal).
> although it’s not exactly humane
That's just propaganda. Exceptionally dishonest propaganda. You should be ashamed to repeat it.
blackeyeblitzar
> That's just propaganda. Exceptionally dishonest propaganda.
Cool. Got any reasoning as to why? Here’s mine:
[quote] An autopsy of Smith's body was conducted by the Alabama Department of Forensic Sciences. The autopsy showed Smith exhibited signs of negative-pressure pulmonary edema, had "dark maroon blood" and fluid present in his lungs along with "marked congestion", and had "frothy fluid" in his trachea. Another death row inmate scheduled to die by nitrogen hypoxia in Alabama in November 2024, Carey Dale Grayson, hired an expert to analyze Smith's autopsy results in August 2024. After a review, the expert called the results "highly concerning."[33][34] Dr. Brian McAlary, an anesthesiologist, wrote in an argument on Grayson's behalf that Smith likely panicked due to an automatic response to the inability to breathe oxygen and that Smith's panic may have been avoided if he had been given a sedative prior to his execution. A second expert, Dr. Thomas Andrew, the chief medical examiner of New Hampshire, agreed that Smith should have been sedated before his execution because nitrogen hypoxia introduces "a sense of the absence of oxygen, air hunger, and all of the panic and discomfort that is part and parcel of that way of dying."[34]
Volker Türk, the United Nations High Commissioner for Human Rights, condemned Alabama's use of nitrogen gas to administer Smith's death penalty and stated that the method had amounted to a potential form of torture and degrading punishment.[35][36] [end quote]
> You should be ashamed to repeat it.
Such ad hominem attacks are against the site guidelines.
dang
[stub for offtopicness]
spacemark
Humans are evolving right before our eyes, everywhere, always.
Still an interesting article, though!
dash2
Yup (blowing my own trumpet): https://link.springer.com/article/10.1007/s10519-022-10107-w...
Mistletoe
I wonder what evolutionary pressures are working on modern humans right now and how they will shape the future?
com
John Hawks, a paleoanthropologist, regularly makes the point [0] that human evolution has accelerated enormously in the last 50k years.
Lactase metabolism is new, in the last 19k years. European skin colours and blue eyes appear to be very recent too, maybe 3.5k years.
Almost certainly there are all kinds of super interesting human evolutionary changes that are occurring now, with our huge population that won’t be visible for thousands of years…
[0] at least since this https://johnhawks.net/weblog/our-new-paper-on-why-human-evol...
hn_throwaway_99
If you look at the complete collapse of fertility rates in the developed world, that is probably the strongest evolutionary pressure humans have faced for millennia.
It is a bit weird to me that the scientific press doesn't talk more about how evolutionary pressure applies here. I think that people are wary to talk about this because it can end up sounding like social Darwinism, or that they believe "Idiocracy" was a scientific documentary.
But it's inescapable, for example, that education rates are now strongly negatively correlated with fertility. While "level of education" is obviously not inherited genetically, I don't think it's too much of a stretch to hypothesize that genetic factors play a role in someone's educational attainment. And, currently, the more education you get, the less likely you are to reproduce (statistically, of course).
Sex evolved to feel really good because for most of human history having sex would usually, eventually lead to babies. Reliable birth control has fundamentally broken that link. Similarly, when a major factor preventing you from reproducing was starving to death, being smarter or cleverer was an evolutionary advantage. I'd argue that advantage no longer exists.
Another simple anecdote: I recently went to my uncle's funeral, and his family was very religious (Catholic). My father, on the other hand, rejected religion and raised us all atheists. My father has 6 descendants, my uncle 24. Again, "religiosity" is not a genetically inherited trait, but I think it would be foolish to believe genetic predisposition plays 0 role.
I say all this just to highlight that, eventually, the "collapse in birthrates" will take care of itself - people with a strong desire and ability to procreate will outcompete, at least in terms of offspring survival, their peers. This will have a huge, profound effect on world society that most academics are too scared to talk about.
swatcoder
Among them, eventually, will be modern medicine if we manage to preserve it long enough and share it widely enough.
By suppressing the consequence of genetic predispositions and vulnerabilities, it lets those genes propagate more freely and invisibly than they would have been doing before. It helps individuals and communities today in a way we can't possibly refuse, but sets up the species to become perpetually dependent on an elaborate, brittle medical infrastructure. Genetic engineering and eugenics could eventually address that, but those invite scifi horrors of their own. We seem to have set ourselves into a bit of a trap.
saalweachter
The biggest thing we're doing now is accumulating a huge amount of genetic diversity, full of all sorts of novel mutations and interesting admixtures.
It's hard to know what genes or traits will be advantageous over the next centuries. The biggest place where our technological advantage still has large gaps that our biology can compensate is disease, and there it's almost random -- a gene that results in a novel protein which is normally advantageous or disadvantageous might have the opposite effect if it makes you exceptionally vulnerable or resistant to a new disease.
nonameiguess
White skin will probably go away in a few thousand years or so. It likely only ever appeared to absorb more UV light and synthesize vitamin D at low sun angles while mostly covered in heavy clothing. Since we can now supplement vitamin D, all the other disadvantages should make it maladaptive.
MichaelZuo
I’ve heard human jaw muscles are becoming smaller and weaker as there’s less need to chew for prolonged periods of time.
Ekaros
I could see plastics, chemicals, for-ever chemicals and in general various pollutants leading various pressures on reproduction. So on medium term there could be pressure for genetics that handle those better.
nickdothutton
Ability to write good dating profiles which appeal to the algorithm.
solardev
Our grandkids will have giant thumbs and tiny brains...
johannes1234321
Only if giant thumbs are useful in using tinder to reproduce more.
sebgr
Everytime I see the word delve in an article I can't help but assume it was written by an LLM which this probably was?
haswell
There were some viral threads going around for a bit that were focused on this word. It never made sense to me - presumably an LLM that outputs the word delve does so because it learned it from the data it was trained on, meaning delve was already a common word.
I personally have used the word for many years, and have seen it extensively pre-LLM. To me, it’s only a red flag when someone starts producing content that doesn’t match their prior history of writing with a sudden explosion of vocabulary.
kzrdude
I think "let's delve into it" is a pretty standard formulation that I see everywhere... And have seen for a long time?
zeknife
I like to think I have a pretty sharp eye for LLM output, and nothing else in the article raised any alarms for me.
camus_absurd
Maybe it is a regional thing like soda, pop, coke etc
shermantanktop
As usual, popular science coverage always casts evolution as an active process, and sometimes even an intentional process. But anyone who took high school science would recognize the form of evolution in the article as just a result of some people dying early while everyone else went about their business.
taeric
I'm not clear on what you mean. The definitive example of evolution that I was taught in school was https://en.wikipedia.org/wiki/Peppered_moth_evolution, which is easily described as you just stated it.
shermantanktop
Right. And if I were a pop-sci writer, my article about it would probably get a headline like "Moths hid in soot by getting darker." Moths didn't do anything, there was no intention.
We are addicted to stories with protagonists, heroes and villains, and so that's how these stories are framed. But that's the exact opposite of what is happening, and everyone knows it, but apparently we just accept it as inevitable.
yard2010
Not GP. This is not evolution, every human is like a lottery ticket, it doesn't change once you draw it. The system "evolves", not humans. Every human is merely a data point (a vector if you will) in this simulation.
digging
> some people dying early while everyone else went about their business
So, evolution - just framed correctly.
reportgunner
I knew enough when the article was explaining what a hemoglobin is.
trueismywork
That's also evolution.
acadapter
Another interesting aspect of modern human evolution is the fact that brave men have a higher risk of dying in war, extreme sports, etc.
Will male risk behavior be more similar to female risk behavior, 10000 years from now?
Nowadays, the use-case for masculine bravery is more or less obsolete. It had a purpose when there were wild animals roaming around human habitations, but nowadays it may very well trick a man into becoming a war casualty.
Historians of the future might look back on pro-conscription advocates as those who stood in the way of the modern human.
tux1968
You're discounting the idea that being a brave man still has any reproductive advantage. I doubt very much that a fearful man is as attractive to women as a brave man, even in modern times.
acadapter
But there are nuances to that.
I know several people who have escaped a war-torn country and had a successful life elsewhere, instead of getting affected by military propaganda, and possibly losing everything just because of other people's territorial conflicts.
acdha
That’s a pretty binary way to describe a spectrum of behavior. The stereotypical sniveling coward, sure, he’s probably not going on a lot of dates but what about someone who’s prudent or careful about the risks they take?
One especially big confound here is remembering the distinction between having sex and having children. From an evolutionary standpoint, the latter is the only thing which matters and unlike animals humans have contraception which completely changes the situation. From an evolutionary perspective the stereotypical bad boy who’s sleeping around constantly might not have even as many children as the cautious, financially stable guy who is monogamous because the former guy’s partners are looking for fun while the latter’s is intentionally trying to start a family.
Y_Y
> remember that we are not descended from fearful men
Edward R. Murrow
solardev
Gotta wonder what happens if aggression is bred out of the population genetics, then the aliens/AI/lost tribes/more isolated countries attack.
As the world moves back to increased nationalism, some cultures are increasingly militaristic while others become keyboard warriors. Over evolutionary time, that could create different enough human subspecies? Maybe we'll see Klingons after all.
scotty79
I believe that last half of a century of relative peace in the West is the direct result of the "bravest" (whatever that label means here) in two world wars. So that less brave men (and women) could build in peace. Unfortunately the population of brave men mostly recovered and we are ready for the next great war in Europe that will devastate everything.
solardev
It's different when you're randomly drafting conscripts from the overall population though, vs having "brave" genes self-select into mortal combat before they can reproduce.
dominicrose
evolution in humans is about who survives, right? more specifically about who survives before having children who themselves survive with or without their parents
being brave may still be a quality if it's paired with other qualities
10k years is a lot, try predicting what happens in 10 years..
solardev
Cultural influences matter a lot too. Even if the parents past down certain genes, a lot of that can be suppressed by environmental or cultural factors, everything from lifestyle to propaganda.
aliasxneo
> masculine bravery
It sounds like you're using a relatively loose definition here. Masculine bravery is not constrained to only the physical realm.
If you read the papers related to the work it's really not all that clear how much of this is genetic (inherited) evolution or just adaptation from birth to different environmental conditions, i.e. any child born and raised at high altitude might display such adaptations, regardless of parentage.
https://www.pnas.org/doi/10.1073/pnas.0701985104
> "Tibetans (the study sample were Sherpas, an ethnic group that emigrated from Tibet to Nepal ≈500 years ago) who are born and raised at high altitude have higher capillary density in muscles as compared with Andean high-altitude natives, Tibetans born and raised at low altitude, or lowlanders."
> "Are These Functional Adaptations Heritable? To evaluate the hypothesis that natural selection accounts for the functional physiological characteristics of Tibetan highlanders relative to Andean highlanders or of highlanders relative to lowlanders, a primary consideration is the presence of heritable variation in the traits under consideration. However, the genetic underpinnings of these quantitative traits are mostly unknown (with the exception of nitric oxide). These traits are also influenced by individual characteristics, including age and sex."
> "With respect to identifying specific genetic loci contributing to high-altitude functional adaptation, efforts so far have not been successful."
An accurate headline would replace 'are evolving' with 'might be evolving' for this work.