It seems like the majority of the comments are not taking into account that this trend began approximately 70,000 years ago - slightly before the various things people here are blaming such as TikTok, Google, writing, Javascript and Twitter.
Cutting-edge (heh) technology 70,000 years ago was the stone blade as well as the earliest known primitive art.
I wish I could upvote this more. I would be willing to bet a number of such comments did not even read the article and responding based on impulse with their gripe about modern society du-jour.
A thing on HN you will see frequently is that someone will be told that X happened and they’ll explain confidently post hoc why.
Occasionally, they will misunderstand this as Y happening and they’ll explain that.
In the best universe, they will misunderstand X having happened as Y having happened and explain it even though Y did not happen.
The existence of this last characteristic makes me trust post hoc explanations very little. Explanations should make falsifiable predictions. It is easy to fit the facts with a false thesis.
The HN rule about not being able to ask if someone read the article or imply/suggest that they did not is the worst rule on the site, because it encourages this behaviour :(
HN needs a lot of rule changes. The narrative of "dang is a great mod" and "HNs rules are actually great" flys in the face of repeated examples of complete incompetence/corruption within HN and it's moderation practices. (E.g. calling discussion about political topics dang doesn't like "ideological flame bait" and deleting the posts.)
dang being great and HN rules being great are two separate claims. It's entirely possible that someone agrees with one of them and disagrees with the other. For example, me. I disagreed with one of the rules. I spoke to dang about it and shared why. He listened to me, shared his perspective on why the rule exists and went out of his way to resolve the issue for me specifically.
He strives to lower the temperature of discussions that get too heated. He tries (and mostly succeeds) to get folks to stay on topic and civil. He keeps the site free from trash or astro-turfing. And he does all this alone.
> complete incompetence/corruption within HN
This is a strong claim. If you have evidence of it, show us. Or retract it.
There is a recent news about elephants evolving to have no tusks... Something that is happening in a relatively short time span. I will no wonder if our modern trends (consuming anything to get pleasure and short-term rewards) will affect our brain size in a similar time span.
That was very much guided evolution though - elephants without tusks get spared, the others get killed for the tusks. There’s nothing like that happening with humans at a population scale, outside the realm of conspiracy theories
If 90% of the people that use social media were culled every 2 years, and only the remaining survived enough to reproduce, we'd (maybe) see some accelerated evolution/correlation in a generation or two, right? (extremely improbable as you're not eliminating a specific physical trait, like in the elephant's case)
> Cutting-edge (heh) technology 70,000 years ago was the stone blade as well as the earliest known primitive art
I think it's important to remember that technology is highly, highly iterative. It's not like if Elon Musk were born 70k years ago we'd have cavemen with electric cars.
In fact, if all of us were somehow warped back in time that far, I fear we'd be even worse off. We know how to roll fiber optic networks and write ML algorithms, but we'd starve before figuring out how to chase down an animal, or know which berries to eat.
If an intelligent modern person with some knowledge of history was sent back to 70,000 years ago (70 kya) we'd probably be able to bring significant help to the group - assuming we were accepted into the group and not immediately killed by our ancestors in peak physical condition. Personally, I'd attempt to introduce:
- art and culture from the far future (flutes, 42 kya; figurative art, 40 kya)
- Simple ovens (29 kya) and pottery (20 kya)
- Rope and various ways to use rope (nets, clothes, bags) 26-28 kya
- Saws (20 kya)
- Dugout canoes (8 kya)
- Basic knowledge of health and disease (concept of potable/non-potable water, "fertility awareness" method for contraception, warm clothing, prevention of injuries, etc)
- Food preservation (salting and drying meat, fermented foods, perhaps sealing things with pitch?)
- Wheeled carts (3 kya)
- "Water bottles": animal skins sealed with pitch
Each of these can probably be made/demonstrated over a period of days or weeks and would likely impress the group. If I was really successful and managed to lead the group, I'd probably try to at least get us on our way to these things (would likely take generations):
- Attempt animal domestication (13 kya)
- Cultivation of barley and wheat (10 kya)
- Water wheel (2 kya)
- Migration to fertile region (Fertile Crescent perhaps?)
I knew a professor that loved getting freshmen classes because he could disabuse them their Yankee in king Arthur's court ideas about how easy it'd be to bring technology back to the past. He had a whole slew of experiments that would explore path dependence and the difficulties of creating technologies with the available resources. Nominally this was to help them not underestimate the intelligence of early humans, but I think he enjoyed it.
These things are easier if you have an idea ahead of time of what you're making, but that has to work in a cultural context and that still doesn't mean they're easy. For instance, how would you would you build a useful saw out of stone? Can you recognize the wild ancestors of wheat and convince someone to keep at the process of domestication for thousands of years?
It's likely that ancient humans were adept at many of these things, like salt preservation, warm clothing, contraception, spun fibers, and boats. Many of the others (agriculture, wheels, etc) simply wouldn't make sense outside their native cultural contexts.
In the meantime, you'd probably have to learn from them the basics of survival.
I feel like the pendulum has swing too far in the other direction on this topic, actually. Yes people in the past weren't dumb, and shouldn't be under-estimated, but even a normal person could provide huge gains to any pre-modern society. Their understanding of mathematics, biology, evolution, medicine, astronomy, economics, reading+writing, organization, etc. are immeasurably valuable. I don't think people appreciate how much "ideas" are, in some sense, a kind of technology in themselves. Yes you probably couldn't make yourself a queen of the land with your advanced knowledge, but you could massively improve this society in fundamental ways. Like get infected with cowpox if you want to get vaccinated (a term meaning of or from cows btw!) against small pox.
>It's likely that ancient humans were adept at many of these things, like salt preservation, warm clothing, contraception, spun fibers, and boats. Many of the others (agriculture, wheels, etc) simply wouldn't make sense outside their native cultural contexts.
For people this primitive, even elementary metalworking would be revolutionary. Yes you'd have to do a bit of tinkering to work out the kinks, but iron ore pre-modern-extraction was everywhere, and once you have the foreknowledge that heat special rock -> smash into shape -> better-than-rock tool it's not hard to figure your way to something groundbreaking.
I do think you'd be limited in how much you could change things by how far back you go, but mostly due to human life span. The more new technologies you need to personally 'invent' the longer this stuff takes, as you'd need to experiment with on-the-ground resources and techniques until you can successfully realize your conceptual understanding. I know what a blast furnace is, and because I have the key concepts I can eventually build one with some trial and error. But it would take years if I had to start from just sticks and sand.
> Their understanding of mathematics, biology, evolution, medicine, astronomy, economics, reading+writing, organization, etc. are immeasurably valuable.
You could tell them that disease is caused by tiny animals, and that the earth is a sphere that orbits the sun, but getting them to believe you is a another thing. And making use of it yet another. You won't introduce quarantine just because of germ theory: book of Leviticus already has a version of quarantine, "the law of the plague" well before germ theory.
> You could tell them that disease is caused by tiny animals, and that the earth is a sphere that orbits the sun, but getting them to believe you is a another thing.
I can find a cholera outbreak, and tell whoever will listen to stop drinking water from the local wells and eating from the local markets. Go to another part of the city for water and food. Those who listen, even if only one, will be my proof. I can also do a cool science experiment with seaweed agar, silver and bacterial growth but that's not as dramatic.
The earth being a sphere that orbits the sun can't be proved without a telescope, but I can propose a vastly simpler and just as accurate approach using kepler's laws. If I was paying attention in high school physics, I can even do cool stuff with Newton's laws of gravitation to show that "As above, so below" (the planets obey the same law of gravity that we earthlings do).
Yes people might still not believe you, as we can be a stubborn and prideful species, but you know the 'why' of many things and so can keep making correct predictions based on that.
> You won't introduce quarantine just because of germ theory: book of Leviticus already has a version of quarantine, "the law of the plague" well before germ theory.
The bible simply lists procedures, it doesn't explain why you do these things or allow you to extrapolate to other situations and scenarios. By contrast, simply by knowing the "why" of infectious diseases, a smart person or government could isolate the cause of - for example - the black death fairly rapidly (rats w/ fleas) and begin taking steps to solve the issue.
A modern person has a head full of correct answers for questions people 2,3,4000 years ago have yet to even ask. That's powerful stuff, and once they've proved their credentials in some way the books they write will advance humanity by millenia.
> I can find a cholera outbreak, and tell whoever will listen to stop drinking water from the local wells ... Those who listen, even if only one, will be my proof.
Results with diseases have a fair amount of chance, as we should all know by now. It might go as you say, it might not. Your disciple might leave and get cholera soon after due to exposure beforehand. A person who stayed and didn't get cholera might attribute their success to the manner in which they prayed. Or your guy's success to the manner in which they prayed.
It's hard to falsify the assertion that "they were not stricken because they were righteous / said the correct prayer", and "statistical significance" is not a dramatic or obvious thing to convey.
I don't think they'd remember the tips about smallpox, considering it hadn't evolved yet. As for iron smelting, we have a wealth of experimental archaeology on the subject under much easier constraints than you're proposing. The DARCs team [1] took 4 years to figure out a usable bloomery based on archaeologically known designs and years of prior experience, and it took a decade more to get all the modern materials out of the design. You could certainly cold-work iron if you could identify the right meteors, but those are rare and notoriously difficult to find [2].
All I'm saying is that you're vastly underestimating the knowledge, skill, and cultural context that went into these technologies.
One wonders if the concept of language 70kya was sufficiently advanced for you to transmit ideas beyond the immediate and concrete. I wouldn’t be surprised if you’d have better luck with water wheels than animal domestication, despite the latter preceding the former.
I've sometimes wondered about this as well. We can all understand how saws work; but can you actually make one from scratch? How about a rope? Do you know where to find the right kind of fibre, how to correctly process it, and then make it in to a functional rope? Do you have the know-how to functionally domesticate wild animals and cultivate crops?
I'd consider myself a pretty handy guy, but if I were whisked away to 70k years ago this very minute then I'd probably struggle with a lot of that, even though I roughly know how to do it. And that is ignore the obvious communication barriers, that you also need to spend time on basic survival, and things like that. A lot of these crafts developed over generations partly because while the concepts aren't all that complex, the actual doing of it in a way that's effective is a lot harder.
I certainly think it'll take a lot more than "days or weeks".
The problem was not to make things, ancients were able to produce few very advanced tools, mechanisms, and technologies, but to save them and pass knowledge of making them to future generations.
To make a dent, you will need a tool for mass spreading of knowledge en masse: a church, a library, a copier, or a book making machine.
Look at prisons with bad nutrition and you’ll notice a large amount of people with some serious muscle mass. If you’re getting regular, very intense exercise (as you would need to as a hunter-gatherer) you’re in the top x% of the world population by fitness, no matter if you’re slightly nutrient deficient. Furthermore, we have at least some reason to believe that prehistoric populations weren’t so badly fed that it led to physical issues - they regularly reached heights equaling that of humans in recent years, far taller than the poorly fed people in e.x. medieval Europe.
Furthermore, modern humans have plenty of disease and issues caused by our modern environment that would render us far weaker 70 kya. Near/farsightedness, teeth issues, diabetes, obesity, repetitive stress injuries, etc. are entirely modern issues. Then look at the comforts we’ve gotten used to (shoes, clothing, soap, a too-clean environment for our immune system etc) - and I have no doubt that a modern human would be in far, far worse shape for the prehistoric life than your average person 70 kya.
Prisons with low calories nutrition have weak thin people in them. Muscles don't grow of you don't eat protein and sacharids - no matter how much you exercise.
You can have sucky nutrition for lack of vitamins etc and those will eventually leave you in bad physical condition. Even if you gain muscle mass temporary, damage to health will be real.
Hunter gathrer also don't have reason to bulk up unlike those prison guys.
Interesting thought experiment. Language/communication barrier and that whole getting murdered for looking different aside...if you were able to accomplish such things, I'd imagine the world you came back to -today- would look much, much different.
You can make pitch by burning certain woods like pine and collecting the stuff that drips from the fire. Also, maybe I’ve been particularly lucky, but I’ve found bituminous deposits in the wild before that would probably be usable. Barring that, tree sap or beeswax would also be very useful for sealing.
I think the answer is the same reason the male brain is larger than the female brain on average. The part of the brain that handles fighting. It's a pretty large part of our brains.
The reptilian hindbrain that handles violence isn't needed nearly as much now that we have society and civilization. It's shrinking.
Because we are being domesticated. Domesticated animals are all dumber than their wild counterparts. Every wild animal that ends up being domesticated ends up with a smaller brain. I should rephrase and maybe say that this doesn't necessarily mean the animals get dumber but they definitely change in the process of domestication and a smaller brain is one of those adaptations. [1]
> The reduced amount of white matter suggests that domestic rabbits have a compromised information processing possibly explaining why they are more slow reacting and phlegmatic than their wild counterparts.
I think the only thing I really quibble a bit with is the description of "dumber".
Our "domestication" has historically been more that we've gone from a generalist species to a specialist society. With that, things that were previously probably a boon for survival and reproduction become less so (For example, quick reaction times don't matter so much when you have a city wall to keep out predators and a backup hunting party).
My assumption is that what we've lost is more our brain matter used to sleep in trees and wake up/run from predators at all hours of the night. Stuff that's less important when you have night watchman, fires, and shelter.
It's similar to how dolphins have huge brains, but most of that is dedicated to sound processing. If dolphins learned how to make huts, farm fish, and fight off predators I'd imagine the part of their brain dedicated to processing sound would start to shrink as there isn't the evolutionary pressure to keep it around.
Sort of like how humans might be evolving towards color blindness because being able to tell the difference between red and green doesn't necessarily increase our ability to have children. That might lead to weird changes in our eyes and brains that could shrink them but wouldn't necessarily mean those humans are any dumber than their predecessors.
I agree that smaller brain does not mean dumber. This is a very simplistic idea of what brains are for. Whales have huge brains, but I would guess that has more to do with their size.
I don't understand what you mean by "generalist" vs "specialist". I think intelligence is related to why, for example, human beings lack armor, fur, and all sorts of specialized features, functions, and excellences that other species have. Human intelligence can dream up an indefinite if not infinite number of functions which are "offloaded" to technology. We wear clothing and can adjust it depending on the climate which allow us to adapt to environments more than any other species. We have optical instruments which can extend our vision beyond that of any other species depending on need. We have all sorts of communication instruments which allow us a greater range of communication than any other species. We can harvest food in ways that put all other species to shame. We can outrun, fly, and swim any other animal. I could go on. Any capacity other species have we can (at least in principle) exceed with the help of technology, all thanks to human intelligence.
Assuming selection as an explanatory model, I don't see why we should expect to see that basic feature going away. Even with greater specialization in one direction or another, you still need much of that basic underlying generality.
AFAIK human natural niche was persistence hunting. Due to our body shape and ability to sweat, we can outrun prey species in the long run. That's how we're engineered, by natural selection in Ice Age Africa. Persistent trekkers that can throw sticks and stones.
Later, we domesticated dogs and other species, then made more and more advanced technologies. But at it's core? Our niche was that.
I'm pretty sure that humans are apex persistence hunters - we can run any animal to death, not just prey species. It's a brutally effective adaptation. It's the greatest weapon we had until fire.
Even fat modern lazy humans have it in them - kick in survival mode brain chemistry and enough luck to keep chasing a deer's trail for days, the deer will die of exhaustion before the human.
Sounds like we need to take control of this evolutionary process and start engineering it. Just because we are no longer required to use these abilities on a daily basis doesn't mean we don't want them. Evolution can go to hell with its "pressures", humanity is supposed to get better over time, not worse.
You're making a value judgement like "better" and "worse" as if there was a clear global optimum that you can reach. Why do you assume that's the case?
Let's assume there even is a global optimum. Why do we think this global optimum would be invariant on environment? We have clear examples of species that fail to adapt to their changing environment quickly enough dying off. If you took the survivors of a change and then changed things back, those survivors might die again. That means you are fit to the environment you find yourself in. As the environment changes, you're not "better" or "worse" than someone who's more fit to a different environment.
Humanity is not getting strictly better on all stats. It's like a video game. We might tweak improve some stats and have to give up others. We are a bit more unique in that we largely optimize for the environment we create for ourselves, but that doesn't mean humans are constantly "getting better" over time. You could maybe try arguing that the human condition has improved over time due to technology, medicine, etc, but even that's an imperfect analysis because our historical record is so inaccurate.
Surely having sharper and more intelligent humans is an objectively better uncontroversial outcome. If there's even a chance that our environment is somehow downregulating important features such as intelligence, we must find a way to reverse that process.
By what metric are you making the claim that humanity does not reproduce?
To my eye we’ve simply unlocked medical science and have taken control of reproduction to the point where it’s not critical to the species for everyone to reproduce. I’d be more concerned about all the plastics and chemicals that are now circulating in our bodies slowly decreasing our ability to reproduce than us as a species being too dumb to reproduce. That position just doesn’t have an existence proof point (no pandas don’t count because while it’s a funny pop meme, all evidence suggests they just can’t/won’t mate in captivity and it’s environmental for them).
> By what metric are you making the claim that humanity does not reproduce?
I'm not. I was replying to the following question:
> What if there's a level of intelligence above which humans decide not to reproduce?
It seems obvious to me that a species that drives itself to extinction cannot be considered intelligent. Doubly so if it does that due to lack of reproduction.
> it’s not critical to the species for everyone to reproduce
It is. Every couple must have a certain amount of children in order to simply maintain a stable population.
> It is. Every couple must have a certain amount of children in order to simply maintain a stable population.
On average. That doesn't mean that every single couple needs to reproduce. In fact, historically, that's certainly not been the case because some couples are just incapable while others reproduce far more than the average.
Is this perhaps too focused on the individual which might not lead to the optimum for the zoomed-out / group (population-level) case?
This reminds me of a meta-system-transition where simplified versions of individual (previously independent) units can lead to a unified cooperative whole that works better at the meta-system level (similar to what led to eukaryotes or to multicellularity). It's like a sacrifice that the individuals make (of things that might have looked like intelligence in the previous context) in order to be able to work together better, and these kinds of transitions have worked out extremely well for life, so far! (I guess I am biased, being alive and everything!?)
Should humans resist the formation of human meta-systems? Human/robot meta-systems? Certainly seems like a good chance that an extremely successful meta-system could be dangerous to the rest of the regular humans!? But if it's actually better, then that's just normal (meta) evolution.
> Should humans resist the formation of human meta-systems? Human/robot meta-systems?
No. I'm saying humans should not lose abilities or features because of it. We should be able to live comfortable lives and still maintain peak physical and mental performance. Any changes in our nature should not go against that.
We specialize though. Some people might be able to maintain peak mental performance. Others peak physical. Some might be better at social things to make sure we have a cohesive well-functioning society. There's probably thousands of character traits and some are going to invariably be tradeoffs in our genome/social conditioning. There's a reason there aren't Einstein-level intelligences running around every day doing body building, modelling, race car driving all at once. You have to choose what you spend your time on and most people choose to intersect that with natural abilities and interests.
Also, assuming the conclusions of the article in any way prove a shift in intelligence (it doesn't), you'd still be looking at averages which tells you nothing about the effect it has on total number at population. Maybe there's an upper bound of "smart" people or "strong" people modern society demands. Certainly as a skill becomes more commoditized it becomes less valuable economically. Maybe we've got too many smart people now because a lot of people saw the explosion in value of such careers?
Also "better" and "worse" only mean something relative to an end. I do not deny ends (I take human nature to be teleological, for example), but many "evolutionists" (i.e., those who accept a basically materialistic worldview) do deny the reality of ends (and are wholly incapable of accounting for them even if reduced to mental phenomena by virtue of having painted themselves into a metaphysical corner).
Eugenics involved horrific deprivations of human dignity for arbitrary decisions of what seemed at the time to be “self evidently good” traits that are much less self evidently good now… if the traits were even retained.
Is that really why eugenics is demonized? That the human race (not any living individuals) is giving up its freedom to some sort of fallible authority?
I guess, like censorship, people only object to an arbitrary subset of it. People love censorship of "really bad" ideas just as they love eugenics of "really bad" genes.
Most people seem happy with asserting our authority of gene selection over animals though :P Conservationism is that. Not to mention actual selective breeding and killing of course. Perhaps we rightly believe humans truly are capable of being benevolent arbiters of who gets to reproduce and who doesn't in animals.
Animal breeding is somewhat different from human breeding.
With animal breeding, there's almost always a set goal. Getting a fatter, tastier, more hardy, or in the extreme, aesthetically pleasing animal.
I doubt we'd really use eugenics for any of them. However, a pure eugenicist might say "Well, why not? Why not select for people less prone to cancer, more physically fit, with better immune systems?"
So then it comes into the question of what eugenics has historically been used for. The worst example would probably be the sterilization of gay people. We used it against mental illness in an age where lobotomy was considered a good treatment for mental illnesses such as hyperactivity.
And all of this, of course, sort of belays the fact that for humans there seems to be no reason why we couldn't use gene therapy in place of breeding programs. Why do we need eugenics when we can directly target the aspects we want in the future generation (and quite a few people would opt in for those changes).
We already seem some of this just in genetic testing of embryos and fetuses. When people know a fetus has downs syndrome, they get abortions and try again. I could see the same with a whole host of chronic illnesses.
People select their own mates. On the assumption that you aren’t just advocating for stuff that’s always happening, you presumably want to set up some authority for who people mate with other than the couples involved. Why can’t they decide for themselves?
It really is pretty similar to the kinds of things that are used to advocate against E2E encryption. An attempt to have the state encroach on territory that used to be private.
> Sort of like how humans might be evolving towards color blindness because being able to tell the difference between red and green doesn't necessarily increase our ability to have children.
Doesn't this hold true for "dumbness" as well? Being dumb is no longer an obstacle in having a reproductive success.
I wouldn't be surprised if there was a peak in the reproduction rate bell curve around IQ 80-90.
Whoa... whoa... let's unpack all the intense presuppositions you're packing in here:
"Domestication" is just a word for a natural evolutionary processes in a symbiotic system. The concept that "domestication" is like, actually a thing apart from evolution is a vastly more difficult idea to parse than it appears on it's face.
>Domesticated animals are all dumber than their wild counterparts.
I mean... again... there are so many things to unpack here. What do we mean by "dumb" and which parts of the brain are being used, and how their size relates to their usefulness. I think it would be extremely difficult to argue any of these claims on their face beyond: small brain -> less brain function, which is extremely spurious.
Homo neanderthalensis had notably larger brains than us, yet they did not survive. Hardly an argument for the idea of greater intelligence -> greater brain size. AFAIK, specific areas in the prefrontal cortex is the primary point of interest when it comes to intelligence, and it's a relatively small section of the brain compared, say, to the visual cortex.
Finally... the most absurd of all the ideas packed in here is that natural selection for smaller brain size would even be a thing. Human mating is openly available for study, I see little-to-no argument for this being plausible beyond some sort of idiocracy world (is this the domestication thesis you hold? I see in the article they are treated separately), which is genuinely problematic. Possibly that certain types of brain sizes are predisposed to certain behavioral patterns. However, the idea that there is even a single evolutionary pattern for billions of humans is pretty ridiculous. We don't have evolutionary islands like other animals do.
> "Domestication" is just a word for a natural evolutionary processes in a symbiotic system. The concept that "domestication" is like, actually a thing apart from evolution is a vastly more difficult idea to parse than it appears on it's face.
In mammals, there is a well-established "domestication syndrome" with a specific proposed underlying mechanism and associated symptoms, including many observed in humans in comparison with other hominids (smaller jaws/muzzles, smaller teeth, smaller brain, greater docility). See https://www.genetics.org/content/197/3/795#skip-link for more information.
The concept that some animals are able to be domesticated, generally, while other's are not, lends itself to the idea that drift toward docile qualities is probably working in the domesticator's favor, and is not an inherent quality of domestication as a concept.
The idea that we have an idea of a thing we can readily point at, does not mean that thing is the driving force behind it. It's just a post hoc argument. We can't domesticate zebras, we can domesticate horses. The idea that 'domestication' is a force, rather than a result of evolutionary pressure of a symbiotic relationship shows that the domestication can't be the driving force. It's just evolution.
I'm not arguing the concept that domestication syndrome doesn't exist. I obviously defer to these experts, I'm just arguing that the concept that free, independent humans 'domesticate themselves' is effectively nonsensical on it's face, as domestication, as such, requires symbiosis and controlled breeding, and is simply not possible for many species.
Domestic animals have safe, boring and predictable environment. It's expected that they'd simplify their brain - the organ that consumes so much energy. If domesticated animals started playing chess, that would be a different story, but they spend their life mindlessly walking between a food dispenser and a litter box, taking naps in between.
This is not how evolution works! They are not in control of their breeding. Evolution is not some intelligent agent with goals. It is like a river, responding to to the path of least resistance in reproduction.
Intelligence and/or brain size not a dominant evolutionary factor unless they are specifically bread for intelligence and/or brain size. Domesticated animal's dominant evolutionary qualities have nothing to do with the animal preferences for mating, thus brain size in fairly arbitrary, and we should suspect it to be some sort of drift, rather than rationally getting smaller.
This is a good point but it does seem like people consistently select for less intelligence because less intelligent animals are more tame and easier to control.
You don't have evidence for that. You presume that less intelligent animals are easier to control, but that's not at all necessarily true. The smaller brain -> less intelligence isn't even something we know.
That doesn't mean that humans are dumber now, though, nor does it mean that dogs were bred to be dumb, nor does it mean that dumb animals are easier to control. Humans with intellectual disability can in fact be extremely hard to control in my understanding!
That wasn't the claim. The claim was about the effects of domestication on cognition and at least for dogs it is very obvious they are less intelligent than their non-domesticated counterparts. Same is true for rabbits. So, at the very least, in at least 2 cases it is clear that domestication has lead to a decline in cognitive abilities. It doesn't take much to infer the same is true for people, domestication has reduced selective pressures on cognitive abilities.
If you know of cases and studies where the opposite is true then I'd like to see the research.
I think you're conflating biological evolution with evolution as a whole. Technology and culture also evolve. Just differently. Evolution is a much wider aspect of existence than mammalian genetic evolution, or even sexual evolution. I absolutely can simplify my brain consciously, by choosing to remember useful, compact things and by choosing to forget useless, complex ones. And then pass that knowledge through our cultural transfer mechanisms.
Why is there evolutionary pressure for the brain to shrink? We seem to have enough calories to feed our brains, and we're not beholden to some master species that needs to economize.
Because we no longer need to run away from predators and process information at the same rate we'd need to in a more wild enviornment. The survival pressures of our ancestral environment are no longer relevant. We've essentially destroyed and driven to extinction every other predator on the planet and now the only selective pressure is adaptation to the human created environment which is much nicer and simpler than the wilderness we came from. Simpler and safer environments make simpler brains and that's my best guess at why our brains are shrinking but I'm just an armchair scientist so it's better to ask the experts. The only remaining selective pressure is basically human predators, a.k.a. sociopaths.
You have this backwards. We are dealing with orders of magnitude more information than we did in ancient times, and we are required to remember a good chunk of it and to be able to recall and use it at a moments notice.
Computers are a big factor in generating all of that information, even if they help process some of it the net effect is a huge surplus.
> We are dealing with orders of magnitude more information than we did in ancient times, and we are required to remember a good chunk of it and to be able to recall and use it at a moments notice.
Surely you mean required, meaning you could end up embarassing yourself in front of your coworkers if you aren't able to recall that particular bit of information.
It's very different from REQUIRED, meaning that if you take a left turn instead of a right turn while running away from a predator you end up in a canyon... or the predator eats you because you have no way to escape...or both.
I don't think I have it backwards. I don't remember anything or know much about the world in general terms. I just know and remember enough key phrases for google to give me the answers when I need them which requires very little cognitive effort on my part. [1]
That wasn't the argument. You seem to be saying that the increasing volume of digital information will require new cognitive adaptations and I'm saying that's not the case because I don't need to be as smart to appear smart on a digital medium, I can just rely on external cognitive aids like google.
Yes but let's say, pre-writing people needed to remember 100% of all information they needed to use - which writing people can offload to tablets and parchments.
Pre-agriculture people had it worse, they needed to remember 100% of all pertinent informations by the hunting band, which had a max amount of 50-100 people. All the predictive abilities for preys in their lands, natural disasters, medicines, rituals, etc.
It's logical that adoption of technology and farming led to lesser pressure for memory recall, at least for the median human.
The brain itself is the evolutionary pressure. It is often repeated that the brain takes ~20% of our body's energy despite being ~2% of our body's mass. If there is no need to have a brain so large (due to a lack of predators) it is beneficial to shrink it.
It's beneficial to lower the brain's calorie intake it if it results in higher reproductive fitness. But like GP said, we have plenty of calories, more than we've had compared to the entire history of humanity. So it doesn't naturally follow that lower calorie brains are higher fitness in 2021.
There are no guarantees civilization won't collapse. The traits that were essential for our survival in the stone age aren't things we want to abandon. I'm a big fan of redundancy.
Beneficial how? Reduction in calories? We tend to have diseases of excess calories in the developed world now. If anything, the greater brain metabolism may actually help by burning some of those excess calories off…
“Use it or lose it” applies in evolution, because of energy usage, but also because of complexity. More features means more things to go wrong, more options for cancers, etc.
Alternately, big brains are recessive/selected against in all circumstances except those from 6mya to 70kya. We've generally removed most selective pressure at this point, if having big brains is due to a combination of recessive traits we'd expect brain size to start shrinking.
I was going to say: maybe it's because we're so successful? We dominate our environment so well that we've made the world a much less threatening place, and so it's not as difficult to survive in the world anymore. Less selective pressure means we end up with a less selected population.
I don't want to turn this into a political commentary, but the modern age is an extreme example of this. You could be the kind of person who doesn't finish high school and can't keep a job, a deadbeat, but still manage to have multiple kids. Even if you don't take care of them, someone else will ensure that your kids survive. Long ago, not being able to are and provide for your kids probably meant that they died.
IMO, as we keep making the world increasingly more safe and comfortable, we might have to resort to genetic engineering. Otherwise, it might be inevitable that more and more genetic disorders will arise, just because we're able to keep people alive with all kinds of illnesses that would have been fatal before. People can argue about the ethics all they want, but it seems inevitable.
Wouldn’t being able to retain maximal genetic diversity actually be a good thing species wide though? Because it also means we have ever bigger achievers in ever more niche but valuable roles.
Screening and abortion are already used to prevent serious disorders. For instance, a huge fraction of downies are aborted. But subtler things are more challenging.
It's possible for an animal to domesticate itself. This is one of the theories for how wolves were domesticated. It's not that humans did anything special to domesticate them but that wolves started hanging around humans and eating the scraps that were left over at campfires and other human habitation sites. Eventually the less fearful and tame wolves became human companions. Once people realized they could hang out with wolves they started actively breeding more tamer variants.
The same is true for humans. The process is obviously slightly more complicated because unlike wolves people have more influence on their environment but it's undeniable that humans are now domestic animals. No modern human can survive in the wilderness and this process is accelerating. We are now, for all intents and purposes, dependent on mechanical tools and technology for our continued existence. Feeding 8B people is impossible without industrial farming and agricultural techniques, e.g. Haber-Bosch. [1]
I did some research into this a couple years ago. There is an interesting theory that we didn't domesticate wolves, but that wolves domesticated us. For one, wolves naturally are very intelligent and pack hunters, so they could have used humans as a hunting partner. For another point, we domesticated wolves way before anything else (atleast 20000 years ago) and that makes no sense since every other animal we domesticated (goat, horse, chicken, etc) will eat pretty much anything and is only of very limited threat to us, whereas wolves are carnivores (very expensive to maintain) and extremely dangerous.
However, if wolves domesticated us as hunting partners, then this starts to make a lot more sense. We didn't need to first learn domestication on easier species, the danger was limited and our hunting would be so much more effective that it was worth the premium.
It also explains why we have the concept of werewolf and why some people have been charged with turning into wolves to be successful in hunting, but never any other animal (there are no cases of ware eagles/falcons). There is something primeval deep inside us that associates wolves with successful hunters.
I find the theory neat, I am not convinced it is true.
Ya, I also don't know if it's true or not. I was just making the point that an animal can domesticate itself by changing its environment and then adapting to the new environment in a way that ends up being essentially a self imposed domestication process.
By society. More intelligence means more likelihood of "waking up". It takes a little bit of ignorance and blind trust to be a cooperative member of society. Once you get too smart, you no longer become useful and then you have to start hunting on your own. Not everyone can do that in today's age, so most people choose to delegate their decisions because the reward is that you get to live without having to think as much.
The Flynn effect is now going in the opposite direction and I don't think it was a good indicator of intelligence anyway because intelligence is more than just IQ. [1]
Yes, people give away their private data for small conveniences, much like how pets give away their natural lives in wilderness for a guaranteed meal and a warm house.
70,000 years ago people were running around in groups of 50-200 people killing mammoths. Private data has nothing to do with this, that’s only happened in the past 20 years and there isn’t a generation that has lived their whole lives with smartphones that are adults yet. We have no idea what effect they’ll have on evolution
Although our brains were getting bigger progressively, around 70,000 years ago they plateaued, and have been shrinking ever since. John Hawks, an anthropologist at the University of Wisconsin, explains how, over the last 20,000 years alone, human brains have shrunk from 1,500 cubic centimeters (cc) to 1,350 cc, roughly the size of a tennis ball.
Except this requires extrapolating brain volume from the skull , which probably inaccurate compared to modern day MRIs. So i would take this claim that brains are shrinking with some skepticism.
Don't you ever forget that intelligence is not directly proportional to encephalic mass. Intelligence is related to number of synapses.
Brains getting smaller doesn't mean any capacity is lost. Maybe the design was improved, as in metabolicaly less demanding, or developmentaly more reliable.
Whales have brains which physically are much, much larger than a human brain; size does not directly equate to intelligence. Note also brains are extremely expensive, physiologically, to maintain. It may simply be we are evolving to be more efficient.
Any potential explanation would have to account for the fact that this happened around the world, not only in certain sub-populations. The article isn't clear on whether it began at different times in different places, possibly because the data isn't complete enough. A start date of 70,000 years ago suggests it has something to do with human exodus from africa that occurred around that time. The difficulty is that even southern africans see the change, suggesting that it wasn't particular to the emmigrees.
I would therefore propose that some event occurred which pushed humans out of africa, which lead to those that remained having smaller brains, and ultimately lead those that left to the same position. Perhaps that explanation is simply population density. Populations tend to expand geometrically, such that the largest portion of population growth occurs in the latest generations. We also know that all modern humans are descended from a very small set of people, maybe as few as fifty (?).
So humans began at that population, slowly expanded across africa for a few tens of thousand of years, started running out of space and were forced to migrate away from africa, then shortly filled up the rest of the earth. Having no where else to escape to, we were forced to deal with increased population density. This lead to lower food availability to support large brains, as well as increased need to reduce aggressive behaviour, achieved via more juvenile brains. Thus, brain sizes reduced across the globe.
The article makes reference to this phenomenon being global:
> Yuval Harari says that the worst choice in the history of human societies is when humans made the transition from nomadic hunter-gatherers to sedentary farmers. With this, humans became much more susceptible to malnutrition, disease, and famine. Their grain-heavy diets lacked critical nutrients that are essential to proper brain function. But, we see brain shrinkage in the aboriginal people of Australia and South Africans, who never succumbed to agriculture until recent times, and we see the same amount of shrinkage in these populations as well.
It's possible as you say that founder effects and reverse migration and interbreeding could account for this, but an alternative theory is that trade emerged as a driving force of human activity, incentivising new behaviours, and so ultimately it was memetics that changed the selection parameters that shrunk brain sizes
Another question not addressed in the article is whether the shrinkage is linear or happened in spurts (and if so, when these occurred). It's entirely possible, for example, that there was some shrinkage 60-70k years ago, then noting happened for 50k years, and then some more shrinkage in the last 10k years.
Another interesting tidbit not mentioned is that you can actually remove a full half of the brain of young children (hemispherectomy) and these people have very normal lives with extremely small or no impact on their brain functions, which is pretty bonkers. This underscores that size isn't everything.
I'm sure some are aware but in case you are not, Lex Friedman podcast recently had an episode with Richard Wrangham [1] where they discuss this. Wrangham is a primatologist that studied alongside Jane Goodall. His theory suggests human's show signs similar to what we see in other species that have been domesticated. This includes smaller face/jaws and smaller brains.
Like others have said, bigger doesn't necessarily mean smarter or more intelligent.
I like to think of a scenario comparing the first commercially available computers being the size of rooms, now we have exponentially more computing power in the size of the palm of my hand.
Assuming it has to do with evolution, it would mean that there are clear breeding preferences that where folks with 'smaller brain' mutations' are likely to reproduce at higher rates than your average person. ( Idiocracy Theory ?)
Is it possible that there is long term development of emergent traits in a species, through a process that is not evolution ?
I don't buy the domestication hypothesis, because I see no proof that aggression has been disincentivized over what we know about ancient human history. There might be unintended consequences, where those who don't go to war are more likely to live and therefore reproduce, leading to propagation of non warring = low-aggression genes.
Lastly:
> This may mean that smaller brains are being naturally selected for. Of course, this hypothesis relies heavily on premises that are both not confirmed and highly controversial.
When the only reason to reject a hypothesis, is that it is controversial, I am inclined to assign it a higher likelihood.
> we developed elaborate speech. We also have advanced culture
I’m surprised there was no speculation involving memes in the article (“meme” as in the original meaning coined by Dawkins).
We’re running a complicated and evolved software suite now. The idea that we have less raw computing to do than our bare-brained ancestors might be worth exploring.
I didn't see in the article any evidence for this shrinkage correlating with intelligence. It seems plausible that the initial adaptation is just raw, inefficient fast growth (ie, evolution solving intelligence the simplest possible way through raw unorganized volume), and the subsequent shrinkage is accompanied by internal structural improvements and optimization. In other words, like we often do in engineering, first we just throw more more hardware at it to fulfill demands, and then as we optimize algorithmic efficiency the extra hardware becomes unnecessary again.
Brain size is a bit of a red herring. Elephants have 3X the brain mass compared to humans.
Though no dummies, but still.
When we think of brain and size, we naturally think of the connection to the intellect. But intellectual activities require patient and slow application of the brain, using external tools like making notes, drawing diagrams and checking one's work for mistakes.
Intellectual pursuits are not actually what the brain is good at. If we make an analogy to computing, it's almost like the intellect is a software layer that is bootstrapped on top of the brain in spite of its shortcomings, using some slow, inefficient scripting language. It's not native to the brain.
An example of what the brain is natively good at is real-time visual processing and control, like navigating in a complex environment full of obstacles and dangers. You don't have to concentrate your intellect for minutes at a time to tell apart a shape from the background; you just point your eyes at it and it pops out at you instantly and effortlessly, thanks to a power in the brain that you can't even control consciously. (Try as you might, you can't not see the shape.)
This is probably why domestication shrinks brains. Perhaps you don't need that much real-time processing in the relatively stable, calm, boring domestic environment.
> Yuval Noah Harari, an Israeli historian and a professor at the Hebrew University of Jerusalem, outlines how big brains are not necessarily better brains in his book Sapiens: A Brief History of Humankind. Our brains use around 25% of the calories we eat a day but account for only 2-3% of our body weight (Harari).
Interesting that our brains are so resource-intensive. It doesn't seem that surprising that natural selection would favor smaller or more efficient brains in many cases.
"There were strong negative correlations found between national IQ and three national indicators of fertility."
I think we should look on with worry that there are people with smaller brains that we are now giving unlimited resources to (food, technology, medicine), via aid and welfare programs. The dysgenic potential is immense.
While the first one is probably really wrong, the other two are clearly fine.
Imagine a unique cat with an IQ of human. Would you say it is more worth to society, than any other cat? Probably so. Is there a magic IQ threshold that renders other cats not as worthy as humans to not be given the same kind of resources? In a way yes, as you would draw a line.
I do love cats, but it's not clear to me what an extremely high IQ cat would be useful for. I suspect it would fall somewhere between lethal and unusually annoying.
A smarter cat plots better ways to murder small animals and calculate more comfortable resting places.
Having a smart ones he seemed to be doing all the cat things pretty optimally.
For social conflicts him being huge enough that other cats and roaming dogs where scared was a lot more useful.
A super high IQ could maybe useful for hunting in dangerous places (it would avoid getting hit by cars and other hazards in cities).
IQ is a culturally-biased measure that, on its best day, is useful for comparing different cohorts and, if it's being used for a good purpose, bridging any gaps. It only measures individual intelligence by a very narrow view of intelligence. There are plenty of high IQ dupes and highly effective people who'd flub an IQ test.
Perhaps it is female (or family) intelligence and impulse control driving the age at which a female paired off and had children.
Paleolithic life expectancy was something like 22 to 33, and much of that after very high infant/maternal death rates. With such life expectancies, females would likely be bearing children at ages we today would find positively shocking. Simply surviving childbirth would be a huge selection factor for both mother and child. And girls become fertile well before they are fully developed physically (yes?), and I suppose their ability to survive childbirth presumably increases a lot with each year after menarche until they are fully grown.
This might be noticed and communicated culturally. There could certainly be selection advantages to parents and families communicating this to their daughters. On the other hand, adolescents certainly want to have sex at early ages, and our ancestors wouldn't have the same hangups and cultural barriers humans have had for the past several millenia. (Indeed, part of the story here is that developing those hangups is, to some extent, adaptive.). And with shorter lifespans, there would have been some expectation of getting on with it. Sex and mating would have been socially "valid" choices at far earlier ages.
If so a girl (/family?) with the intelligence and self-control to 1) notice this and 2) act to postpone mating, even by a year or two, could do a lot to improve a girl's/woman's odds of surviving childbirth and so passing on her genes. If (a big if?) we presume that these characteristics are related to brain size, that might explain it. (If the ability to notice, and communicate, the advantage of waiting were in the _parents_, that would still be be selective for intelligence/control.)
As human lifespans extended, pressure to reproduce at an early age would diminish, and it would be easier to create and communicate the cultural norms protecting girls from maternity before they were fully grown. Indeed those norms would become adaptive, as having sex too early would be needlessly dangerous. At which point, _all_ girls would be protected from premature pregnancy, and the selection for intelligence/control would diminish.
(Apologies for any ignorance of how the ability to bear children changes after menarche, I have only the standard male knowledge of these things. And for "girl"/"woman" nomenclature issues, the ages in question here are very different than the ones we are today accustomed to.)
> Paleolithic life expectancy was something like 22 to 33, and much of that after very high infant/maternal death rates.
This is a widespread belief but it is an urban myth. Most of the average mortality from the Paleolithic is weighted downward due to infant and childhood mortality. If you lived past 15 years there was a good chance you would grow old. A 2008 study found that once infant mortality was removed the average life expectancy was 70 to 80 years! [0]
> our ancestors wouldn't have the same hangups and cultural barriers humans have had for the past several millenia.
Citation needed. Rules over access to women is found across ancient societies and cultures. In patriarchal societies women are a valued good and bargaining chip between men, hence the cross-cultural dowry paid to the father. Promiscuity would have been even more problematic then than today because of small, tight-knit communities where paternity controversy could cause a major social disruption in the clan.
My guess is that average individual brain size and intelligence just isn't as important in collaborative society. Once you start sharing knowledge (orally at first, written later), you don't need everyone to figure everything out on their own.
There's a also a huge variation in human brain size. [1] suggests almost a factor 2. I don't know if variation was similar 70.000 years ago.
It seems that now we use around 10% of the brain power. Maybe we were optimizing for energy consumption?
Until the second half of the last century it was hard for the majority of people to find enough food.
I would expect that our brain will start to grow slowly if food won't be a problem for a long period. The same way our bodies started to grow once we had enough food.
It's a well known fact that domestication of wild animals such as wolves causes the head and brain size to shrink over multiple generations.
It's probably the same thing happening in humans. It would be interesting to measure the brain volume of politicians and business leaders to see if they follow the same trend as the general population.
From the article it indicates this shrinkage began 70K years ago, or 65K years before writing. In addition, vast majority of the population didn't know how to read or write until 100-150 years ago.
Maybe it’s just language in general. If I’m in a tribe with 100 people, and we all know to talk, not everyone needs to remember every single thing you might ever need. If you forget something, you can ask around, and probably someone remembers.
On the contrary, we create more abstractions and complexity from more people which create more complex social dynamics, more inventions, words, ideas, etc. In addition, tribes were not so static in Pre-agricultural eras. Tribes would regularly trade or swap members, and some would grow or collapse entirely.
I definitely move through life seemingly in a mechanical fashion. I suspect in the wild I would be alert, all attention, always anticipating, planning.
Only habitual things that you've already learned are done so mechanically. But you've already learned magnitudes more than your ice age ancestors as well as your pre-industrial and pre-information age ancestors. You've flexed parts of your brain and had to use more abstract knowledge than they ever had to.
I suspect that some other factor is responsible for the shrinkage. It could just be pure sexual selection. Maybe we find smaller more symmetrical heads to be more attractive and we sexually selected for them over tens of thousands of years. Also could be responsible for domesticated animal brain shrinkage, as we select for more attractive animals.
Could it be true that our brains got more complex even as they got smaller or did we legitimately lose some IQ points from the shrinkage?
Cutting-edge (heh) technology 70,000 years ago was the stone blade as well as the earliest known primitive art.
An interesting guide whenever you're trying to put this kind of thing into context: https://en.wikipedia.org/wiki/Timeline_of_prehistory