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#evolution#more#humans#selection#children#years#trait#genetic#traits#pressures

Discussion (49 Comments)Read Original on HackerNews

chr15m20 minutes ago
Lactose tolerance is a classic example of a recently evolved trait.

https://en.wikipedia.org/wiki/Lactase_persistence

hn_throwaway_99about 2 hours ago
Given that fertility rates are currently plummeting worldwide, the principles of natural selection would dictate that humans are currently undergoing very high selection pressure for specific traits.

Basically, any genetic trait that causes people today to think "You know, I think I'm going to remain childfree" is specifically selected against, and any trait that causes people to want more children will be selected for. I'd argue that the invention of reliable birth control was that biggest change in human selective pressures in history. Evolution made sex highly pleasurable and desirable because it often resulted in passing on your genes. That's no longer true with reliable birth control, and with such a huge environmental shift natural selection will act on other avenues that cause people to have children.

gblarggabout 1 hour ago
> any genetic trait that causes people today to think "You know, I think I'm going to remain childfree" is specifically selected against

More specifically, the genetic trait of being susceptible to the childfree brainwashing. People aren't born not wanting to have kids, since all their ancestors did.

chmod775about 1 hour ago
One reason our ancestors had plenty of children is that children were a large net-benefit to them.

Many modern societies are structured in a way that makes children an economic negative to their parents. From an individuals' POV, the "smart" play is not having children and hope others do.

Individuals believe that they do not need children because they have saved up for retirement, not accounting for the fact that if everyone did this and there was nobody left to do any work once they reach retirement age, that money will be worthless and they'll be unable to retire. The alternative is mass-scale immigration, and that's becoming unpopular. For an example of what happens if a society has neither enough children, nor immigration, see South Korea. Poverty among the elderly is rampant and they are increasingly being forced back into the labor market.

Many western societies needed to start applying a large multiplier to parental benefits decades ago.

derektankabout 1 hour ago
>People aren't born not wanting to have kids, since all their ancestors did.

What evidence do you have that all their ancestors wanted to have kids? I can think of a lot of reasons why people may have had kids without necessarily wanting them. They wanted to have sex in an era before birth control. They were pressured into it by the social norms of their local community. They were raped. Etc.

I have a lot of criticism of the childfree movement but I think it’s pretty disrespectful to assume they’re not being honest when they say they don’t want to have kids and that they’ve always felt that way.

chmod775about 1 hour ago
Birth control is older than the Bible[1], it just wasn't as effective. Humanity as a whole was very aware how babies come to be.

Ways to have fun without coitus aren't a recent invention either.

Human reproduction and raising children is an unusually taxing, time-, and resource-intensive process, which is why we've applied our considerable intellect to plan for that since forever.

[1] https://en.wikipedia.org/wiki/History_of_birth_control

margalabargala41 minutes ago
Involuntary reproduction has been a tiny tiny minority of births for the past few millenia at least. It happens and is awful but it should not be construed to constitute a large part of any person's ancestry.
dachrisabout 1 hour ago
True, and here's an interesting twist: as you wrote, this is mainly happening due to "I think", so it's primarily on a memetic level. Humans also pass on lots of thought/behavioral aspects to their children (memes). Therefore I'd expect that selection on the behavioral level is happening much faster than on a genetic level.

Idiocracy's "stupid genes win" likely won't happen, my theory is that selection will remove memes (behavioral/thought/cultural patterns) that cause childlessness from the meme pool much faster.

Could also well be that natural selection will rear it's ugly head again first. I previously thought that people rejecting the evolutionary theory (creationists etc) were just backwards and anti-science. But I've realized since that this is a too simple judgement. The ethical implications of evolution are dark. Humans have had a word for selection since the dawn of language - "death".

A bit sad that paraphrasing Paul Watzlawick in this context fits very well: one cannot not participate in evolution.

keeda27 minutes ago
Am I the only one who thought that was a given based on phenomena like this:

https://www.nationalgeographic.com/science/article/bajau-sea...

we all are not quite freediving most of our waking lives, but the daily pressures of modern urban living must be exerting a similar level of evolutionary pressure on us.

deepsunabout 2 hours ago
As far as I was taught in college, evolution never stops, but we're just too short lived to notice that. We _may_ notice some very tiny blip on timescales of several hundred years, but last really noticeable traits happened many thousands years ago.

However, cultural/society/educational evolution happens much-much faster (but is also much-much weaker, can disappear on just a few weeks).

vikramkrabout 2 hours ago
The idea that humans have undergone high selective pressure for genes related to immunity in some way during a recent 5000 year period in which massive urbanization lead to a truly unfathomable amount of deaths including staggering percentages of humans dying in childhood because of various infectious diseases, plagues, pandemics, etc, and that those changes involved large numbers of small changes across a large number of genes in complex regulatory networks, is probably the least surprising discovery in the history of the universe. It's good science and it's obviously important research to do, not in the least because it can shed light on evolutionary pressures that may be driving the rise in autoimmune diseases we see in the modern day, but the framing of the PR slop article around it is truly so stupid.

Maybe if it found selective pressures were still dominating and driving evolution in recent decades in developed nations with low childhood mortality that would be surprising. Though the framing of the article is almost that it would be surprising if mutations were happening at all which is obviously stupid - we haven't figured out how to reverse entropy so mutation rates haven't gone down, evolution by genetic drift is obviously continuing to occur, and with advances in medicine the number of folks surviving with mutations that would have been problematic otherwise is increasing.

Truly disappointing slop. Like obviously humans faced selective pressures during an era when like 8 in 10 kids died of plague or similar things, a biological factor where survival is correlated with genetic factors that influence immunity and disease survival.

Again, super useful science to see exactly what that influence was, but it would only be surprising if we learned we'd somehow managed to turn off entropy and statistics during the black death and we didn't face selective pressures.

_moofabout 1 hour ago
I can't find the source now but an idea that really stuck with me is that evolution happens on the margins. If a 0.0001% increase in the height of a giraffe makes it 0.0001% more likely that the giraffe will survive and reproduce, then in 1 million years giraffes as a species will become taller.

As for humans: I mean, duh? The selective pressures faced by humans have changed radically in the time we've been around.

fhnabout 2 hours ago
Genetic drift is not evolution. Every single birth brings about genetic drift. Evolution is gaining or losing specific traits. Individually, humans do gain and lose traits but from an macroscopic view, those traits are just a blip. An cheetah that lose it's ability to run fast many not survive. A human that loses a some useful trait does not die(government assistance. I'm talking about the West because I can't speak for every place in the world) and might even pass that trait down the line. An cheetah that gains the ability to run even faster thrives, outcompete competitors, and most likely pass on this trait. A human that gains a useful trait(faster, stronger, better vision, better hearing) does not amount to much;, might win competitions and make a bunch of money but many people can make a bunch of money without that trait so it's nothing really special. Overall, it's a wash because in one generation, you might have some good genes and the next generation, no so good genes. Therefore, no evolution.
hn_throwaway_99about 2 hours ago
This is certainly not what I learned to be the definition of evolution in my biology classes.

First, the article is not just proposing genetic drift, which is the change in allele frequency by chance. It is arguing that change in allele frequency is due to natural selection pressure, and that most certainly is evolution. Copied from the Wikipedia entry, because I think it's simple and clear:

> Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as genetic drift and natural selection act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations.

That is exactly what the article described.

rendawabout 1 hour ago
The article is talking about the last 5000 years, GP is talking about the last 50-100 years. I think most people who say that natural selection is over are talking about ~100 years and not 5000 years.
remarkEonabout 1 hour ago
Right, but, those people are wrong. "This trait didn't die out in 2 generations. Evolution is over!"
adrianNabout 2 hours ago
I believe the traits for humans you should look at are not physical like strength, but social. People with poor social skills are less likely to reproduce in our society. Likewise, culture (and hence memetic evolution) influences birth rates quite a bit and is passed on from parents to children.
arjieabout 1 hour ago
Well notably the loss of skin pigmentation evolved in two different ways after migration into Europe and separately into East Asia. There is strong selective pressure in Africa so pigmentation remains there.

And lactase persistence is quite recent. Some people say that Tibetans and some S E Asians are particularly adapted as well to their local environment of high altitude and sea diving but I don’t know anything about that.

noduermeabout 1 hour ago
>> might win competitions and make a bunch of money

You mean, they might be more likely to have lots of offspring than someone who was disabled and living on government assistance?

Or 500 years ago, be more likely to slaughter the men and rape the women of a neighboring kingdom, than those who stayed home?

Or for a trait closer to my heart, be adept at handling the intellectual requirements of surviving exile and persecution?

You know it's the success they confer toward reproduction that causes traits to survive or not, right? Without reproduction, of course one generation's genetic noise is just noise. And longevity traits don't survive if they hamper reproduction. Just the opposite: Lots of traits that succeed because they improve the chances of breeding are the worst possible things you would want for longevity. Risk taking behavior and all manner of psychoses have survived and thrived for millenia not because the individuals with them live long, but because they breed prolifically.

lomlobonabout 2 hours ago
Isn't this obvious? Why on earth would it stop? I don't actually believe that 'humans stopped evolving' was ever a widespread belief among scientists. This article has gotta be lying to me.
derektankabout 2 hours ago
I have definitely run into the belief that humans aren’t evolving anymore (though not among scientists). I think people with an incomplete understanding of evolution look around, see most human beings survive to adulthood, and assume that there must be no more evolutionary pressures on us (perhaps with the phrase “survival of the fittest” tinging around inside their head). I honestly don’t blame anyone who hasn’t been exposed to the concept of e.g. sexual selection for making the assumption.
delichonabout 2 hours ago

  There's been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we’ve built with the same body and brain. -- Stephen Jay Gould, "The Spice of Life", 2000
Gould was an evolutionary biologist and Harvard professor, and one of the most prominent popularizers of evolution since Darwin, but somehow believed that it doesn't apply to modern humans.
remarkEonabout 2 hours ago
That's such an extreme claim. It defies common sense. You'd have to proclaim that there was some event that _stopped_ evolution in humans, universally. How is that even possible? Especially 50k years ago. I'd be a little more forgiving if the claim was that evolution stopped in, say, 1999.
knowaveragejoeabout 1 hour ago
For the average person considering this question it also goes without saying that it's hard to grasp the time scales involved.
adrianNabout 1 hour ago
There are a couple of species that remain essentially unchanged for the last couple million years. Why can't humans become one of them?
remarkEonabout 2 hours ago
Perhaps it was not a widespread belief among scientists, I don't know, but if you were to posit in front of polite company that humans are today and always have been under evolutionary pressures that select for certain traits you would have gotten some odd looks. The implications are possibly a little uncomfortable, especially if what this article suggests is true and the pace of evolution is accelerating.
jona-fabout 1 hour ago
Who said we stopped evolving? Evolution is slow cause we are many. Another garbage clickbait press release that butchers the science.
jiggawatts37 minutes ago
It is well established that evolution is driven not only by fitness in the trivial sense of "survival or death", but in large part by mate selection.

(Disclaimer: The rest is a personal theory with zero scientific support.)

This begs the question: selection based on what? In many bird species it is the complexity of the male's song, or the colourful beauty of his feathers. There are "dances" and courtship rituals in many animals, including even insects.

Humans almost certainly also subject to evolution caused by the evolutionary pressures of mate selection!

This is best said by Anthony Hokpins in Westworld: https://www.youtube.com/watch?v=OjsGJOXhPGU

"I read a theory once that the human intellect was like peacock feathers. Just an extravagant display intended to attract a mate. All of art, literature, a bit of Mozart, William Shakespeare, Michelangelo, and the Empire State Building—just an elaborate mating ritual.

Maybe it doesn't matter that we have accomplished so much for the basest of reasons. But, of course, the peacock can barely fly. It lives in the dirt, pecking insects out of the muck, consoling itself with its great beauty."

Which is a good bit of drama, but... if true, what are the consequences for the evolution of the human species?

Assume for a moment, that yes, women are attracted to male intelligence, which men show off with music, art, and "great works".

The obvious immediate effect is that this causes the average intelligence of Homo Sapiens to increase over time.

But the secondary effect is more interesting: judging intelligence benefits from more intelligence! As the next generation of women inherit greater intelligence, they become better judges of male intelligence, more picky and precise. This forces male intelligence to increase ever faster to keep up with the "rising demand". Rinse and repeat.

I can't prove, but strongly suspect that this is the case.

Birds of Paradise become "more beautiful" on the scale of aeons because more beauty in the males doesn't improve the judgement of the females.

Humans become more intelligent on the scale of mere millenia because more intelligence does improve the judgement of the females.

Terr_26 minutes ago
> > just an elaborate mating ritual.

You might find the book Blindsight interesting, since... Well, to avoid spoilers, I'll just say the story doesn't put our concept of intelligence on the usual top-of-creation pedestal.

Joel_Mckayabout 1 hour ago
True, but not in the way most people would find admirable. Civilization is getting less intelligent, more impulsive, and catering to neurology wildlife predation often attenuated in the past.

Human-beings will likely evolve into a primate equivalent of a Chihuahua. =3

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danwillsabout 2 hours ago
I'm reminded of this section of a Douglas Adams quote:

"Anything that, in happening, causes itself to happen again, happens again."

I like how this is not even specific to life nor genes, and it's not hard to add to it the idea of happening-again in ways that make the thing better-or-worse at happening again.

Personally I think this applies to all coherently-causal systems.. still trying to figure out whether to believe QM is fully causal or not! (Currently seems like it might be a mixture?)

serious_angelabout 2 hours ago
The choice for the illustration is marvelous, no words... I love it...

Thank you for mentioning the Artists of so ineffably magnificent works:

- https://luisajung.com/

stevenaloweabout 2 hours ago
sure seems like a lot of 'em have
dangabout 1 hour ago
Maybe so, but can you please not post unsubstantive comments to Hacker News? We're trying for something a bit different here.
bebe83949rjabout 2 hours ago
There is infine diversity of genders and orientations. Human is also the only mammal that can change its gender in adulthood!
nozzlegearabout 1 hour ago
Humans are the only mammals with genders at all. Are you confusing gender with sex?
bebe83949rjabout 1 hour ago
Both are synonyms! Like when pretend "woman" sports are not for woman, but "female" only! Or woman should be in mans only prison, to get raped!
prologicabout 2 hours ago
If that's true. Why haven't we evolved into a species that doesn't harm each other or the environment?
adrianNabout 1 hour ago
Traditionally, harming other people and the environment has made it easier to feed your own children (or at least the children of your tribe) and have more of them.
_moofabout 1 hour ago
Because that isn't what evolution does. Evolution is the process whereby traits that make reproduction more likely under selective pressures become more common. There is nothing in that process that necessarily implies a lack of harm to each other or the environment.
lioetersabout 1 hour ago
Evolution does not necessarily mean getting smarter or better in any way other than more adapted to the environment (natural and artificial). We could be getting stupider and more violent if that leads to hoarding more food and reproducing more in the given context. It's also not evenly spread throughout the species, some could be evolving various abilities while the rest are stuck in a plateau or even regressing.

Similarly with social progress. There is a common myth of linear progress through history, where humanity now is better than we were a century ago, a millenium ago, and ten thousand years ago. In some ways we're better, in other ways we don't even know what we've forgotten and lost.

What we want is conscious evolution, where we shape the direction that we wish to evolve towards. Unfortunately with the state of politics we've lost decades of progress in a very short time.

mhurronabout 2 hours ago
Because we became an incredibly successful species doing just that.
danwillsabout 2 hours ago
I think that that might be an aspect of the reproductive fitness of the 'hive' (or meta-organism) of all humans, rather than the genes in any individual or population.

I agree individual humans mostly seem to behave more like single-celled micro-organisms and it's a stretch to call it a collective-organism, but it's also not impossible to see the relevant analogous aspects though I think! (like, the internet could be one example?)

It's an interesting question whether the human species (or life-as-a-whole?) viewed as a single-system will be able to reproduce itself. Sounds like the question only makes sense when talking about settling elsewhere than Earth.. Mmm, reminds me of the Fermi Paradox. Will we make it through this!?!

deepsunabout 2 hours ago
Wars did become less violent, but the on scales of several hundreds of years. I'm not talking about industrializing death, but about desire of violence (civilian suffering, genocide). Evolution is very slow.