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…
This makes me sad every time - I know for a fact that mountains are evolving, but in my lifetime the mountains are just mountains. Still. Not changing a bit unless I'm looking really really close (which means that it's not the mountain that changes, but merely its surface).. So the same with humans.
I don't care about living forever, I just want to see what happens in 10k years. Just out of curiosity.
There’s a really great sci fi book that touches on this, I’m blanking on the name. They can “bobble” up regions of space which basically freezes time for a duration in that region. Highly recommend.
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.
> 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).
Far from inescapable, this is just a phantom of noisy data.
It's easy to find statistically communicative population slices where family size is quite high and so is level of education (ignoring that "level of education" is a culturally specific and disputable measure in the first place).
What we really see is that integration into the modern US/EU-inspired "universal middle class" urban culture, which now spans the globe, seems to correlate with lower birth rates and family sizes. But there are countless factors contributing to what makes that culture unique and that could easily be playing a role in the birth rates and family sizes.
That said, it does suggest that the this "modern" culture needs to induct outsiders in order to maintain its scale since its proving relatively poor at growing its own population among insiders. What that means for the future is unclear, and if you're personally all in the on the "modern", it can easily look concerning or even bleak in the way you describe.
You're mistaken. Polygenic scores for educational attainment correlate negatively with fertility in the US, UK and elsewhere (in fact, AFAIK everywhere it has been tested). So it's not just because people in poor countries have more kids.
Note also that natural selection is about correlation not causality. If an lab accident blows up MIT, that will select against intelligence, even though intelligence wasn't causal.
I highly doubt birth control has altered the selection process in humans in the span of two or three generations.
I think you're right for the wrong reasons. Correlation does not equal causation. I think it's very clear it's our modern lifestyle. Our diet. Many of us are over weight. Most of us are sedentary. We're consuming higher percentage alcohol and weed. We're consuming other drugs. There are microplastics in our blood stream and the food we eat. There are chemicals like BPAs that were in our products for years before we removed them. Pollution. The list goes on. I would rule out these factors first before ever considering the idea that evolution is at play.
The fact that you have said this makes me think you have misunderstood my point.
I am not arguing that genetic differences are responsible for any change over the past couple generations. I am strongly arguing that there is now an enormous new selection pressure, i.e. a new factor that strongly affects fertility rates, and over time (and, perhaps a very long time) that genetic inheritance will respond to that selection pressure. That is inherently how evolution works.
People love to say "correlation is not causation", but all evolution really works with in the first place is correlation. That is, the environment changes, and then organisms that happen, through "the genetic lottery", to not be able to reproduce in that new environment are outcompeted by those organisms that do. My argument is that the environment that determines whether humans reproduce has changed drastically over the past ~100 years or so, and that this will affect which genes are likely to be more prevalent in the future. I am not arguing this genetic change has already happened.
> But it's inescapable, for example, that education rates are now strongly negatively correlated with fertility.
You can easily say that city dwelling is strongly correlated with higher education rates, and higher noise pollution, therefore high noise pollution is strongly negatively correlated with fertility. Correlation doesn't equal causation.
> Reliable birth control has fundamentally broken that link.
Reliable birth control has severely reduced unwanted pregnancy, but there's a whole host of people who would like to have children that can't.
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.
>but sets up the species to become perpetually dependent on an elaborate, brittle medical infrastructure
How is this any different than the transition from hunter-gatherers to agriculture caused us to "become perpetually dependent on an elaborate, brittle agricultural infrastructure"?
Agriculture took hold in numerous civilizations and indeed introduced one of the primary threats of collapse for those civilizations. Throughout history, we can see civilizations collapse when their dependence on agriculture faltered, which happened often enough.
But neither the technology (agriculture) nor its failures (blight, famine, etc) were universal and so it hadn't become a threat to the species as a whole.
Modernity, however, has become aggressively global and more successfully universalizing. We not only invite every community into it, we insist they do so for their own good. Further, its technological contrivances (and therefore their brittleness) are more intense because of industrialization and later accelerating technology. As it continues to progress and expand, it brings the whole species into its gamble and raises the stakes of that gamble at the same time.
I don't think you've interpreted that quite right. Modern wars aren't funded by the bank accounts of the people profiting from them. War is a wealth transfer to the top.
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.
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.
But is there an evolutionary pressure in this direction because of the decrease in need? That would be Lamarckian then. I wonder if certain traits need evolutionary pressure to stay stable, and otherwise degenerate in some specific direction.
Many (most?) traits require energy to develop and maintain. A stronger muscle will need more energy so there's always pressure to reduce it. That pressure may just be countered by pressures in other directions.
Something something opportunity cost? If you can allocate your next bit of energy and protein to something with better bag-for-buck than a jaw muscle then that should be an evolutionary advantage.
More expected (over ensemble of specimens) evolutionary "fitness" per unit of whatever you need to expend to make a jaw muscle a bit stronger. The buck is small because we're doing optimization calculus.
One thing to consider is that some things might not be genetic, but environmental. I think jaw muscles are one such thing and short-sightedness might be other. First caused by food we eat and the other by less natural light and less time spend outside in childhood.
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.
The primary "pressure" at the moment is to develop species-level self awareness to stabilize the planetary life support system before we crash civilization.
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...