hckrnws
Investigating the case of human nose shape and climate adaptation (2017)
by thunderbong
On a slightly related topic, I remember to have seen an exposition where an artist was asked to represents what a human who has naturally evolved to survive a car crash might look like. And it has a cool / terrifying website: http://www.meetgraham.com.au/view-graham
Quite fascinating topic to wonder about: how long will it take for the modern era to genetically change us ?
Men will evolve to manage sperm banks and fertility clinics.
After the high profile grossness with those, you'd think every person using those services would do a paternity test just in case.
To answer your question, it already has changed us in many ways. You are not the only one who does not realize this though. It is in fact the prevailing position.
We have diseases and genetic defects, among other impacts through modern behaviors and environments/toxins, which are also retained in the genetic mutational load. We even have a whole lot of energy and human activity working to counter evolutionary pressures and assure those accumulated mutational loads remain in the genetic code.
Fitness depends on the specific environment the creature is in. Environmental fitness for the ancestral environment when all humans were hunter-gatherers is not necessarily the same as fitness for living in an industrial society. Evolutionary pressure still works just fine.
Humans are beyond evolution. There's no meaningful selection pressure in our environment that kills people before reproductive age, so there's no reward for adaptations.
This simply isn't how evolution works. There's no way to be "beyond" it. It's an inevitable facet of populations of living organisms.
If a population used genetic engineering to collectively ensure their genetics didn't change, no mutations, no other populations involved, then... I guess? Otherwise, there is this staggering multitude of influences.
Living longer and reproducing longer is a huge weight on the scales of evolution. Why does anyone need to die early for it to work?
Totally wrong, killing humans is not required for evolution.
Ignoring genetic drift and taking into account only natural selection, all that's needed is differences in fitness, i.e. differences in how much an individual contributes to the gene pool of future generations.
This. “Natural selection” refers to selection and survivability of traits, not of individuals. Evolution is how that selection process then manifests itself over time in a population.
can't remember where i read this, but significant and big leaps in evolution seem to often happen in times of crisis when the environment forces it. that's not to say that evolution doesn't happen all the time with little pressure it's just very slow when things are more stable. by extension big leaps in evolution can really be down to a low number of individuals. read an article about a genetic study claiming the human population was down to a few thousand individuals around 90k years ago.
Crisis presumably doesn’t affect the rate of mutation, so is the mechanism here just that there is a tight filter that from the perspective of future animals made the species more like themselves, because by definition the future animals have passed the filter?
Like the traits must have already been present in some lower frequency pre crisis, and the crisis distills the traits which are selected for by the crisis.
So probably less evolution moves faster during crisis and more that there is an interesting survivorship bias related to crisis when analyzing the change of a species over time.
Well...
Evolution is not primarily driven by the mutation rate. It's primarily driven by differential success of already-existing genetic variation. Over the very, very long term, you need mutation to be the source of that genetic variation, but over the short term mutation is mostly just harmful, and this:
> Like the traits must have already been present in some lower frequency pre crisis, and the crisis distills the traits which are selected for by the crisis.
is correct.
> So probably less evolution moves faster during crisis and more that there is an interesting survivorship bias related to crisis when analyzing the change of a species over time.
This is conceptually wrong; in this context "survivorship bias" bears a technical name you've probably heard of, "natural selection". A stronger survivorship bias means faster evolution.
That all seems logical. What is the connection to the previous point?
Punctuated equilibrium.
Not sure if he's the originator, but I'm pretty sure I learned about it in a Richard Dawkins book.
no one is having babies mon ami. birth rates are declining.
it's not about killing people before reproductive age, it's about absolute numbers of offspring born. dying before reproducing ensures that number stays 0, but you can still hit sexual maturity and not reproduce.
plus there is a fertility window -- after 50 most humans, male or female, ain't having kids (a handful of rockstar types whelping babies at 80 notwithstanding).
there is a TON of meaningful pressure in our environment, like the inability to have a living wage reducing how many Gen Z's are marrying and having kids.
> it's not about killing people before reproductive age, it's about absolute numbers of offspring born.
Technically, it's about averaging offspring (weighted by your genetic contribution to them) across all of time. If you have 30 children, and all of them starve to death before reproducing, you've reproduced less than your neighbor with the one child and one grandchild.
But that's impossible to calculate, so mostly we just have to work with number of children. This detail, though, is something you might want to keep in mind when looking at reports of "effective population" in the past. Any actual population in the far past who end up being wiped out in the middle past are excluded from the "effective population" that we calculate.
There is incredibly high sexual selection. Birth control is effecting this.
Note that sexual selection selects for health, wealth and reputation. Women are doing most of the selection here.
Evidence?
Take just the easiest to measure of those factors, wealth. Per your hypothesis, wealthier men should have more babies. Do you have any evidence that wealthier men have more babies?
In fact, it's quite the opposite. There is a strong inverse correlation between wealth and number of babies. Both globally [1] and in the US [2]. There is some data that you can seek out that will suggest the trend is reversed in some first-world countries in the past couple of years, but that's no where near enough time to draw conclusions.
Is there real evidence that men with greater "health" (besides the obvious, of, say, having a crippling disease) or "reputation" have more children?
I'm sorry, but this sounds like "women only chose alpha males" junk to me.
1. https://en.wikipedia.org/wiki/Income_and_fertility
2. https://www.statista.com/statistics/241530/birth-rate-by-fam...
Per my hypothesis I never said wealthier men should have more babies. Birth control is a factor here.
Women do marry and prefer richer men. Hypergamy is scientifically true, you can look it up if you want. But birth control changes the outcome even though hypergamy is an influencing factor.
In addition I said health and reputation are factors. So a man with good health but low wealth has one positive factor in his favor.
I feel your entire reply is rude and over the top. Calling my statement junk is not conducive to discussion.
If there's a fertility gradient based on heritable traits then there is evolution happening.
I believe we are currently measuring recent functional selection on humans and it's non-zero. That is, empirically you are incorrect.
Interesting. So how do you explain menopause and other population or age scale adaptations?
Humans aren't individuals, no matter how certain blips of modern culturalism pretend.
That's what the build up of plastics in our testicles are for.
Really? I was under the understanding that we have continued to get taller and bigger driven by out our access to nutrition and medicine over the last couple of centuries.
Is this really a genetic adaptation to the environment or rather fulfilling the inherent growth potential that would otherwise be inhibited by nutrient deficiency?
By all the 'no one under 6'2"' tinder jokes I'd say it's being incorporated into genetics.
I have always considered that a bug, not a feature.
I would like to see if there is a correlation between Sleep Apnea cases and nose shape to determine if there is a link between humans living in an area they are not adapted to and how that affects their ability to breathe normally.
I suspect the impact would be extremely small compared to BMI, so it would be likely that there would be a link because of some dependent variables.
Ok, what about looking at nose shape of diaspora that have historically (multigenerationally) high BMI? Not an expert but might suggest Inuit, some Pacific Islanders, Māori, west Africans maybe. How are their noses shaped and anything that might help with apnea?
I bet there is also a large correlation with computer/phone neck and posture
Sleep apnea usually comes from the back of the throat. It’s not a nose thing as much.
People probably sleep in very similar conditions in all climates.
On a slightly related issue, I noticed that my nose gets bigger,in my photos, it turned out it was mostly irritation swelling due to pollution, while in a Nordic country with cleaner air quality, I noticed that is back to normal. And now I am always checking iqair.com- and it says:"PM2.5 concentration is currently 3.6 times the World Health Organization annual PM2.5 guideline value.
If I'm reading this right, the hypothesis seems to be that in drier climates, humans need longer noses (simplifying) to increase the humidity of the air to an optimal level.
Did the authors propose a counter-evolutionary pressure, to favor a shorter nose in more humid environments?
It's possible that the mechanism would be as simple as "it requires more resources to maintain a longer nose," but I'm also wondering if they suggested anything.
From the author summary:
> We find that variation in both nares width and alar base width appear to have experienced accelerated divergence across human populations. We also find that the geospatial distribution of nares width is correlated with temperature, and absolute humidity, but not with relative humidity. Our results support the claim that local adaptation to climate may have had a role in the evolution of nose shape differences across human populations.
I really wonder how nose shape can affect evolution. What is the mechanism? How can better air lead to higher numbers of successful offspring or fatalities?
> How can better air lead to higher numbers of successful offspring or fatalities?
Try running XX hours after an antelope and report back, most animals aren't optimised for long distance, humans are, you can hunt most things by following them and waiting for them to collapse, surely having better air intake helps. It might be something as dumb as more antelope meat = more social points = you get to bang more.
Why do 70%+ of the world population has brown eyes ? It offer marginal UV resistance but nobody becomes blind or sterile because they have blue eyes, certainly not before they can reproduce. Chances of reproduction can also be dictated by other things like attractiveness, and these are also very dependant on cultures and time periods.
Its more like if your tribe has access to more meat they can produce more offspring. I wouldn't think of this in terms of individual prowess.
Pretty sure the best hunter gets the most kids on average.
Source?
> Try running XX hours after an antelope and report back, most animals aren't optimised for long distance, humans are, you can hunt most things by following them and waiting for them to collapse
According to this theory, the rhythm was to walk a long long time and maybe hungry too, then a burst of activity, then stuff your face, then pass out for a while, then repeat. It seems logical & sensible & probable.
Well, at least one selection pressure for blue exists - modestly better vision in low light levels.
Nose filters, and adjusts air temperature and humidity - it's not just a passive in/out hole.
Evaporation is a big factor in both controlling temperature and water retention/loss ( that's why dogs pant in hot weather ).
Remember the surface of your lungs are topologically on the outside - they are large and wet and are sensitive to both physical dust etc as well as potential infection.
The nose design has to find the best balance across all these factors ( as well as being important in the sense of smell ).
Respiratory efficiency is a pillar of health and performance, from sleep to hunting and fighting. I wouldn’t be surprised to find that marginal gains make a big difference and can be passed on.
The article mentions an increase in upper respiratory tract infections in the air being breathed in is not humid enough. The hypothesis seems to be that in drier climates, humans need longer noses to increase the humidity of the air to an optimal level.
The parameters affect the temperature and humidity of the air that reaches the lungs. E.g., a long slender nose could perhaps moisten and warm up dry frosty air better than a shorter wider nose.
Speaking as someone with a long slender nose, I have my doubts about it moistening dry frosty air. During the Winters, the only thing my nose seems to be good for is producing blood and dried mucus wafers like some cursed Triscuit factory.
It's not about your nose. It's about the relative differences of the air reaching the lungs when inhaled through different nose. You may not think that your nose does a very good job (or perhaps I picked a wrong example), but perhaps the job would get done much worse by a short wider nose.
Some environmental parameters are temperature and absolute humidity. But there are also significant differences in sex when a other parameters are equal. So perhaps the correlation is not so straight forward.
I can see that. Contrary to my personal feelings about my own nose, having grown up in a more Northern latitude where Winters were much, much harsher than what I experience now, there was a few key things I learned at an early age that stuck with me well into adulthood.
Breathing through your nose in the cold while walking to class was one of them. I heard this a lot back then, the logic being as you propose; that it just gives the cold air a bit more time to warm before it reaches your core. Adding to that, you were also supposed to breathe slowly, rather than taking fast, gulping breathes. That just added to the reasons to avoid over-exerting yourself in the cold, which poses other risks.
Other stuff had more to do with choice of clothing material, layering, etc, but that's not really applicable to this conversation.
Interestingly, while it still does get cold where I live now, nobody really pays attention to these rules. I'd say the difference between the two areas is something like -5F on average, give or take. I am not sure how significant that is.
> Breathing through your nose in the cold while walking to class was one of them.
After extensive nasal surgery in 2009 this became an option for me again, after over 20 years when it wasn't.
I discovered a less-discussed rider: yes, it seems gentler on the lungs to breathe in through your nose in sub-zero weather, but there is a condition: you should breathe out through your nose as well.
Exhaling warms the structures in the nose so it can warm the next inhalation.
But, for me, that same sub-zero weather often causes my nose to make more mucus -- so breathing both in and out means a lot more use of a handkerchief, or a nasty snotty moustache.
It's sometimes simply not worth it. :-/
Honestly, all this makes zero difference if you're not frail or in advanced age. I regularly experience winter temperatures of -30°C or lower (-40° is not infrequent), and it really doesn't matter how you breathe.
Might make a big difference if you are exerting yourself, eg cycling.
Discussion here from 2019 about heat exchanger masks seems relevant. They warm incoming air using the heat from outgoing breaths.
Andean Indians are known for fairly wide, prominent noses. They also have massive thoraxes and lung capacity.
Yay free proteins!
Silly suggestions related to snoring:
- harder to find mating partner before earplugs were inventend
- easier for your enemies/predators to catch you in your sleep
Going to use this as a comeback next time my wife makes a comment: "I'm just well-adapted to certain climates, so there!"
Weirdly, I saw this paper mentioned just this morning, in the context of an r/AskHistorians post discounting the possibility of an African origin for Olmecs. Sounded interesting, and then I saw it linked here.
Same. Feels like we exist in a very small bubble doesn't it?
West African, but not East African? That seems like an enormous problem in itself.
There is a rather distinct type of nose which I've only ever observed with people of Ukrainian ethnic descent.
Now I wonder if that is in fact some type of adaptation to local climate because the people of the surrounding areas don't seem to have that nose shape to the same extent.
so indeed jews are the spawn of satan since there must be quite dry in hell.
There are a large amount of enviromental adaptations in many human populations, a lot of them to do with enzimatic adaptations. Climate as a term in this context is only usefull if you include, everything, diet, the ability to pass certain contaminents, such as high arsinic concentrations in water, vs binding say calcium. The full list, is, well, everything!, horribly complex, the nose ,perhaps working as a proxy indicator for a number of less visible adaptations, as succes in more extream environments is absolutly dependent on multiple adaptations, none of which is optional over generational time spans, as extream conditions, in an already extream environment, are going to eliminate marginal indivduals.
>This work was supported in part by the United States National Institute of Justice, the United States Department of Defense
This is how our understanding about the world moves forward.
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Also there is a relatively new (5800 years ago) mutation somehow related to brain development, the ASPM gene. The mutation is somehow advantageous to the individual, but we don't yet know exactly why/how.
Crafted by Rajat
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