Could Malthusian tragedy be the Great Filter? Meaning, maybe most civilizations, before they develop AGI or space colonization, breed so much that everyone is too busy trying to survive and reproduce to work on AGI or spaceflight, until a supernova or meteor or plague kills them off.
Since humans don’t seem to be headed into this trap, alien species who do fall into this trap would have to differ from humans. Some ways this might happen:
They’re r-selected like insects, i.e. their natural reproduction process involves creating lots of children and then allowing most to die. Once technology makes resources abundant, most of the children survive, leading to an extreme population boom. This seems unlikely, since intelligence is more valuable to species that have few children and invest lots of resources in each child.
Their reproduction mechanism does not require a 9-month lead time like humans’ do; maybe they take only one day to produce a small egg, which then grows externally to the body. This would mean one wealthy alien that wants a lot of children could very quickly create very many children, rapidly causing the population’s mean desire-for-children to skyrocket.
Their lifespans are shorter, so evolution more quickly “realizes” that there’s an abundance of resources, and thus the aliens evolve to reproduce a lot. The shorter lifespan would also produce a low ceiling on technological progress, since children would have to be brought up to speed on current science before they can discover new science. This seems unlikely because intelligence benefits from long lifespans.
Evolution programs them to desperately want to maximize the number of fit children they have, even before they develop civilization. Evolution didn’t do this to humans—why not?
Human technological progress doesn’t seem to be as fast as it can be, though, which suggests that there’s a lot of “slack” time in which civilizations can develop technologically before evolving to be more Malthusian.
Your Malthusian collapse seems to be conditional on some particulars of aliens’ biology, but the Great Filter has to be very very general and almost universal.
Agreed. But the Great Filter could consist of multiple Moderately Great Filters, of which the Malthusian trap could be one. Or perhaps there could be, say, only n Quite Porous Filters which each eliminate only 1/n of civilizations, but that happen to be MECE (mutually exclusive and collectively exhaustive), so that together they eliminate all civilizations.
That seems correct to me, but it is quite different from your original proposal.
Can you think of other filters that are MECE with the Malthusian trap? I don’t see obvious ones. Maybe a good way out of the Malthusian trap would be mechanisms that limit procreation, and those make interplanetary colonization—which is procreation of biospheres—seem immoral? I don’t think that sounds very convincing.
They’re r-selected like insects, i.e. their natural reproduction process involves creating lots of children and then allowing most to die.
That doesn’t seem like it would lend itself to evolving culture. Specifically, since parents don’t invest in their offspring they don’t tell them what they’ve learned. Thus no matter how smart individuals are, knowledge doesn’t pass to the next generation.
Perhaps they create lots of children, let most of them die shortly after being born (perhaps by fighting each other), and then invest heavily in the handful that remain. Once food becomes abundant, some parents elect not to let most of their children die, leading to a population boom.
In fact, if you squint a little, humans already demonstrate this: men produce large numbers of sperm, which compete to reach the egg first. Perhaps that would have led to exactly this Malthusian disaster, if it weren’t for the fact that women only have a single egg to be fertilized, and sperm can’t grow to adulthood on their own.
Specifically, since parents don’t invest in their offspring they don’t tell them what they’ve learned. Thus no matter how smart individuals are, knowledge doesn’t pass to the next generation.
Maybe the alien species has some other form of sharing information. For example the parents may share the knowledge with anyone, and later someone else will tell their children.
I am not suggesting a specific mechanism here, rather objecting against the generalization that alien species will have no way to pass knowledge to the next generation unless they do it like we do. There can be other ways.
First, this is probably a poor candidate for the great filter because it lacks the quality of comprehensiveness. Remember that a threat is not a candidate for a great filter if it merely exterminates 90%, or 99%, of all sentient species. Under those conditions, it’s still quite easy to populate the stars with great and powerful civilizations, and so such a threat fails to explain the silence. Humans seem to have ably evaded the malthusian threat so far, in such a way that is not immediately recognizable as a thermodynamic miracle, so it’s reasonable to expect that a nontrivial fraction of all civilizations would do so. At least up to our current stage of development.
Second, I’ll point out that bullets two and four are traits possessed by digital intelligences in competition with one another (possibly the first as well), and they supplement it with a bullet you should have included but didn’t- functional immortality. These conditions correspond to what Nick Bostrom calls a ‘multipolar scenario’, a situation in which there exist a number of different superintelligences with contradicting values. And indeed, there are manysmartpeople who think about the dangers of these selection pressures to a sufficiently advancd civilization.
So, malthusian pressures on biological systems are unlikely to explain the apparent lack of spacefaring civilizations. On the other hand, malthusian pressures on technologically optimized digital entities (possibly an obligate stage of civilization) may be much more of a threat, perhaps even one deserving the name ‘Great Filter’.
This filter applies even before they invent technology. Brains use lots of energy and development time. This is typically selected against. Therefore most organisms only evolve the minimum amount of intelligence they need. And human level intelligence is never an advantage in most environments.
So you need some really weird set of conditions to create an environment that selects for high intelligence, and doesn’t select too strongly against energy efficiency or development time. I don’t know what these conditions are, but they only occurred once on Earth, over hundreds of millions of years. This suggests these conditions occur very rarely, and we might just be very lucky.
I think a too easy reproduction mechanism means not evolving intelligence. The selective pressure for human intelligence could not have came from the environment or else many species would be similarly intelligent like how many species can fly. It was some sort of a competition inside our species, probably sexual. And when reproduction is easy, sexual competition is not so tight. In fact, the most likely answer is that the runaway explosion of intelligence that resulted in us must be probably a mutually reinforcing process: intelligence made reproduction harder, hence more sexual competition, hence more pressure for intelligence.
How did intelligence make reproduction harder? Through big heads making childbirth harder. Frankly I don’t know why didn’t evolution just came up with the idea of giving women gigantic hips and large vaginas, but what happened instead is that babies are born far too prematurely so that their head size is not too big, and thus require a huge amount of care and investment after birth. This, postnatal maternal investment, then intensified sexual competition and thus pressure for more intelligence.
It was some sort of a competition inside our species, probably sexual.
A currently popular theory (at least, at the pop sci level, I don’t know how it is regarded by actual scientists) is that intelligence snowballed due to social competition of all against all—an arms race. The smarter people are, the better they can detect lies, but also the smarter they are, the better they can get away with lying. Everyone needs to be as smart as possible just to keep up, until the process runs into a limit, such as the size of the birth canal. Expanding that by widening the pelvis adversely affects mobility.
But that looks like a just-so story. Why did that process happen to humans and not chimpanzees? To which one answer might be: It could have happened to a different branch of the primates, it just chanced to happen to our ancestors first. Someone had to be first, and they’re the only ones smart enough to be having this conversation. Once started, the process was so fast that every other creature that didn’t reach take-off has effectively stood still, and in the modern world they stand no chance except by our permission.
I think it is not a just-so story, it largely predicts everything it should and fails to predict everything it shouldn’t. Runaway processes require feedback, I think this is the key. Look for the thing that intelligence made harder. That thing is birth and babycare. Intelligence makes it hard, this causes X to be stronger, and X causes more intelligence, that is the feedback process. What could X be? Sexual competition. More: http://lesswrong.com/lw/mcj/open_thread_jun_15_jun_21_2015/chju
It was some sort of a competition inside our species, probably sexual.
I’m not sure about that. Be very skeptical of claims that something evolved due to sexual selection, it tends to be the default explanation lazy evo-psy people reach for when they can’t immediately think of a better explanation.
Wait, what? What are even the alternatives? The only alternatives are environmental pressure—food, predators etc. But such an environmental pressure affects a lot of species at the same time and for this reason, most traits in the animal kingdom have the expected normal distribution. Such as the ability to swim amongst mammals—many can swim a little, some better, and a few really well. Yet the distribution of intelligence in species does not follow normal distribution. Humans are far, far ahead from the species in the second places (apes, dogs, dolphins). If it was environmental pressure, adult chimpanzees were basically like retarded humans or humans who are stuck at the mental capabilities of a 10 year old. Bonobos would be flipping burgers at McD. (OK some people do claim that certain dogs have the IQ of a 5 year old human but it is really a stretch. Their communication ability and suchlike does not even compare.)
Being so far ahead can mean only one thing—the selective pressure MUST have came from withing the hominid species, not from the environment.
But what could hominids compete for? Not food. Food is also an environmental variable and if we don’t see e.g. gorillas compete a lot of for food, we should assume there was enough around.
This gives really only one option left.
Factor in that runaway processes MUST have, I will risk a “per definition” here even though it is not math, a feedback element. Whatever X-factor (lol) pressed humans to get more intelligent, must have been made worse by humans getting more intelligent, so it exerted even more and more pressure or how else could it be such a runaway process.
This is useful, because it suggests we should just look at what was made worse by the evolution of intelligence and we found the feedback factor. And the answer is obvious: reproduction. Childbirth, the physical process of getting the head out, and the babycare.
In my mind it is a fairly strong set of evidence and it not only predicts everything we want it to predict here, it also reliably fails to predict everything it shouldn’t and that is what a good theory should do.
For example, if food scarcity was a selective factor, we would have iron stomachs, able to eat everything. In reality, we have shit for stomach, we need to cook our food, we cannot digest most leaves nor grass—the most available resource! - we get ill easily and so on. Sure, human diets have a wide variance, but it seems we are really picky eaters, going for the special stuff, not the easy available stuff: leaves, grass, carcass. What does that suggest? It suggests no food scarcity.
Or say predators. Most animals try to protect themselves from predators with claws and fangs. Again, we have crap in that department. If there was any serious pressure there, we’d kept these around.
So what kind of environmental pressure is left, really?
I am also surprised that it is you who say it, because I had the impression you give some credibility to the set of views that are sometimes called red pill or manosphere. They are 100% based on sexual selection shaping human nature, without that they haven’t any chance of getting anything right.
This is what I mean by lazy evo-psych. You dismiss the alternatives using hand waving logic and assert that it must be sexual selection even though one could dismiss sexual selection just as easily by hand waving. Let’s go through you comment piece by piece.
The only alternatives are environmental pressure—food, predators etc. But such an environmental pressure affects a lot of species at the same time and for this reason
And different species respond to [edit:similar] environmental pressures in different ways.
most traits in the animal kingdom have the expected normal distribution.
This is the only part of your comment that might be worthwhile, assuming you have data about the traits actually being normally distributed and are not just doing the lazy statistician thing of assuming all distributions are normal. Even then, it’s not clear that this doesn’t apply to traits that are the result of sexual selection.
Being so far ahead can mean only one thing—the selective pressure MUST have came from withing the hominid species, not from the environment.
I’m not sure what the distinction between environmental and intraspecies selection pressure that you’re trying to make here is supposed to be.
But what could hominids compete for? Not food. Food is also an environmental variable and if we don’t see e.g. gorillas compete a lot of for food, we should assume there was enough around.
First yes gorillas compete for food. Second the claim that “there was enough around” is silly. If there’s enough food around, a species’ population generally increases until it either reaches the Malthusian limit or it’s stopped by some other factor, e.g., disease.
Factor in that runaway processes MUST have, I will risk a “per definition” here even though it is not math, a feedback element. Whatever X-factor (lol) pressed humans to get more intelligent, must have been made worse by humans getting more intelligent, so it exerted even more and more pressure or how else could it be such a runaway process.
This is useful, because it suggests we should just look at what was made worse by the evolution of intelligence and we found the feedback factor. And the answer is obvious: reproduction. Childbirth, the physical process of getting the head out, and the babycare.
I’m trying to parse the above argument as anything other then a complete non sequitur and failing. Perhaps you can help: Suppose we have a hominid of above average intelligence, how does the above translate into a causal mechanism that leads to him having more decedents?
In my mind it is a fairly strong set of evidence and it not only predicts everything we want it to predict here, it also reliably fails to predict everything it shouldn’t and that is what a good theory should do.
In particular if sexually selection is responsible for intelligence, we would expect highly intelligent people to be highly sexually desirable especially when considerations like resource constraints are removed from the picture. We now live in a highly prosperous time, and to say that nerds aren’t sex gods would be a gross understatement.
For example, if food scarcity was a selective factor, we would have iron stomachs, able to eat everything.
Why? Yes, iron stomachs are one way to adept to food scarcity, they aren’t the only way.
In reality, we have shit for stomach, we need to cook our food,
More interestingly we can cook food, i.e., we can partially pre-digest our food externally, which is another way to adept to food scarcity.
we cannot digest most leaves nor grass—the most available resource! - we get ill easily and so on.
It’s actually incredibly hard to digest leaves and grass, that’s why cows, etc., need four stomachs.
Most animals try to protect themselves from predators with claws and fangs.
No most animals protect themselves by being really good at running away, or having a hard shell/hide. In fact nearly all animals that have claws or fangs are predators themselves and use their claws and/or fangs for hunting.
I am also surprised that it is you who say it, because I had the impression you give some credibility to the set of views that are sometimes called red pill or manosphere. They are 100% based on sexual selection shaping human nature, without that they haven’t any chance of getting anything right.
Just because some aspects of human nature are shaped by sexual selection doesn’t mean all aspects are.
I’m not sure what the distinction between environmental and intraspecies selection pressure that you’re trying to make here is supposed to be.
Food is a resource outside the species, sex is a resource inside the species.
Suppose we have a hominid of above average intelligence, how does the above translate into a causal mechanism that leads to him having more decedents?
In particular if sexually selection is responsible for intelligence, we would expect highly intelligent people to be highly sexually desirable especially when considerations like resource constraints are removed from the picture. We now live in a highly prosperous time, and to say that nerds aren’t sex gods would be a gross understatement.
Wait a bit here. We are not talking about going from 120 IQ to 140 increases the number of descendants. We are talking about going from 80 to 100 does. On that level the distinction is not between super smart nerds vs. everybody, but more being able to handle normal things vs. shooting yourself in the foot all the time.
Of course, that environment, that social environment was far simpler. Still if you ever hang out with simpler people (e.g. what in the UK is called a flat roof pub ) it is typically the 80 IQ guy who insists on fighting some other guy for no good reason whatsoever and it is the 100 IQ friend who is telling him don’t be an idiot he is twice your size and did time for stabbing someone. Or you see how dumber criminals get busted on really trivial mistakes—if all you have is tribal customs instead of laws it probably still works the same way. Or, maybe, the difference between a 80 IQ and 100 IQ tribal warrior is largely that the later does not think “we are the awesomest” is a good enough reason to attack a tribe that has three times as many warriors. In short, while really high IQ does not help with reproduction much, really low IQ provides excellent opportunities to shoot oneself in the foot in a competitive social environment. What we today consider average IQ simply translates to a hominid who is a bit cautious and can assess when to be brave and when to be a coward. Not some super nerdy level of intelligence.
Even today, I would say there is an IQ threshold below which people have lower number of children. I don’t think Idiocracy the movie got it exactly right. While the dumbass having 4 kids with 4 different single moms is a popular trope, in really the really dumb guys tend to go in and out of prison or be really ridiculous at pick-ups because they cannot think of anything to say really beyond “nice tits”. The charming simpleton with the 4 different single-moms is actually going to be somewhere closer to the average IQ.
Sure, a peacock having a REALLY huge tail may be detrimental to its reproductive success because it cannot even go through a mating dance routine maybe, but that is no evidence wrt to the average sized one not being more useful than the small one. Same for intelligence.
Still if you ever hang out with simpler people (e.g. what in the UK is called a flat roof pub ) it is typically the 80 IQ guy who insists on fighting some other guy for no good reason whatsoever and it is the 100 IQ friend who is telling him don’t be an idiot he is twice your size and did time for stabbing someone. Or you see how dumber criminals get busted on really trivial mistakes—if all you have is tribal customs instead of laws it probably still works the same way. Or, maybe, the difference between a 80 IQ and 100 IQ tribal warrior is largely that the later does not think “we are the awesomest” is a good enough reason to attack a tribe that has three times as many warriors. In short, while really high IQ does not help with reproduction much, really low IQ provides excellent opportunities to shoot oneself in the foot in a competitive social environment. What we today consider average IQ simply translates to a hominid who is a bit cautious and can assess when to be brave and when to be a coward.
Note that none of your examples are cases of sexual selection.
While the dumbass having 4 kids with 4 different single moms is a popular trope, in really the really dumb guys tend to go in and out of prison
Sure, a peacock having a REALLY huge tail may be detrimental to its reproductive success because it cannot even go through a mating dance routine maybe,
A REALLY huge tail is detrimental because it makes the peacock more likely to be eaten by a tiger, i.e., non-sexual selection. If peacocks were placed in an environment without tigers females would chose even larger tails. Heck they’ve done experiments where they glued on extra tail feathers to give a lucky peacock an even larger tail, the result being that females preferred those males to any males with a natural tail.
Heck consider an actual example of sexual selection in humans: Men like women with large breasts. Notice how common ridiculously large breasted women are in everything from advertizing to anime to video games. Heck in ancient times people would worship multi-breasted fertility goddesses. Contrast that with the portrayal of smart men, who must be given an actual “sexy” trait (like being rich or a badass) for women to accept them as “sexy”. For example, Q’s gadgets contribute to James Bond’s (not Q’s) sex appeal even though he’s not the one developing them.
Sexual selection doesn’t end at being attractive. It could be everything from killing competing suitors to making sure kids have a good career. Just as every organ is a reproductive organ, drawing the borders of sexual selection is hard. Everything cashes out in reproduction, where I try to draw the line is that the survival of individual animals against the forces outside the population is not, so getting food and getting away from predators is not. But pretty much everything inside the population is. But even getting a lot of food can be an aspect of it… crap. The point is that the traditional/popular views of evolution tend to be “survivalist” and basically this intra-population competition / sexual selection stuff is largely everything else that it is not directly survivalist but is about competition for things beyond the survival of the individual. Be that sexual partners or childrearing.
And yes, in this sense Mr. Dumb taking a knife to the heart in a pub and his girlfriend hooking up with someone else is an example of this intra-species competition...
Yes, you could define “sexual selection” that generarly. However, I don’t think a terms that refers to everything is particularly useful.
And yes, in this sense Mr. Dumb taking a knife to the heart in a pub and his girlfriend hooking up with someone else is an example of this intra-species competition...
Yes, but I wouldn’t call that sexual selection unless the fight was specifically over the girlfriend.
More generally, you can imagine a lot of failure modes where an alien species evolves to become intelligent, but cannot build technological civilization because it cannot achieve large scale social cooperation.
E.g. imagine a society where human brains evolved just a little bit differently and >90% of population are dyslectics. This very obviously wouldn’t matter until about the time proto-writing changed into true writing, i.e. after urban development and proto-states. But then, such a civilization is trapped.
Could Malthusian tragedy be the Great Filter? Meaning, maybe most civilizations, before they develop AGI or space colonization, breed so much that everyone is too busy trying to survive and reproduce to work on AGI or spaceflight, until a supernova or meteor or plague kills them off.
Since humans don’t seem to be headed into this trap, alien species who do fall into this trap would have to differ from humans. Some ways this might happen:
They’re r-selected like insects, i.e. their natural reproduction process involves creating lots of children and then allowing most to die. Once technology makes resources abundant, most of the children survive, leading to an extreme population boom. This seems unlikely, since intelligence is more valuable to species that have few children and invest lots of resources in each child.
Their reproduction mechanism does not require a 9-month lead time like humans’ do; maybe they take only one day to produce a small egg, which then grows externally to the body. This would mean one wealthy alien that wants a lot of children could very quickly create very many children, rapidly causing the population’s mean desire-for-children to skyrocket.
Their lifespans are shorter, so evolution more quickly “realizes” that there’s an abundance of resources, and thus the aliens evolve to reproduce a lot. The shorter lifespan would also produce a low ceiling on technological progress, since children would have to be brought up to speed on current science before they can discover new science. This seems unlikely because intelligence benefits from long lifespans.
Evolution programs them to desperately want to maximize the number of fit children they have, even before they develop civilization. Evolution didn’t do this to humans—why not?
Human technological progress doesn’t seem to be as fast as it can be, though, which suggests that there’s a lot of “slack” time in which civilizations can develop technologically before evolving to be more Malthusian.
Your Malthusian collapse seems to be conditional on some particulars of aliens’ biology, but the Great Filter has to be very very general and almost universal.
Agreed. But the Great Filter could consist of multiple Moderately Great Filters, of which the Malthusian trap could be one. Or perhaps there could be, say, only n Quite Porous Filters which each eliminate only 1/n of civilizations, but that happen to be MECE (mutually exclusive and collectively exhaustive), so that together they eliminate all civilizations.
That seems correct to me, but it is quite different from your original proposal.
Can you think of other filters that are MECE with the Malthusian trap? I don’t see obvious ones. Maybe a good way out of the Malthusian trap would be mechanisms that limit procreation, and those make interplanetary colonization—which is procreation of biospheres—seem immoral? I don’t think that sounds very convincing.
Filters don’t have to be mutually exclusive, and as for collectively exhaustive part, take all plausible Great Filter candidates.
I don’t quite understand that Great Filter hype, by the way; having a single cause for civilization failure seems very implausible (<1%).
That doesn’t seem like it would lend itself to evolving culture. Specifically, since parents don’t invest in their offspring they don’t tell them what they’ve learned. Thus no matter how smart individuals are, knowledge doesn’t pass to the next generation.
Perhaps they create lots of children, let most of them die shortly after being born (perhaps by fighting each other), and then invest heavily in the handful that remain. Once food becomes abundant, some parents elect not to let most of their children die, leading to a population boom.
In fact, if you squint a little, humans already demonstrate this: men produce large numbers of sperm, which compete to reach the egg first. Perhaps that would have led to exactly this Malthusian disaster, if it weren’t for the fact that women only have a single egg to be fertilized, and sperm can’t grow to adulthood on their own.
Maybe the alien species has some other form of sharing information. For example the parents may share the knowledge with anyone, and later someone else will tell their children.
Why would they? That would increase the evolutionary fitness of their competitors.
They could trade the information.
I am not suggesting a specific mechanism here, rather objecting against the generalization that alien species will have no way to pass knowledge to the next generation unless they do it like we do. There can be other ways.
I have two somewhat contradictory arguments.
First, this is probably a poor candidate for the great filter because it lacks the quality of comprehensiveness. Remember that a threat is not a candidate for a great filter if it merely exterminates 90%, or 99%, of all sentient species. Under those conditions, it’s still quite easy to populate the stars with great and powerful civilizations, and so such a threat fails to explain the silence. Humans seem to have ably evaded the malthusian threat so far, in such a way that is not immediately recognizable as a thermodynamic miracle, so it’s reasonable to expect that a nontrivial fraction of all civilizations would do so. At least up to our current stage of development.
Second, I’ll point out that bullets two and four are traits possessed by digital intelligences in competition with one another (possibly the first as well), and they supplement it with a bullet you should have included but didn’t- functional immortality. These conditions correspond to what Nick Bostrom calls a ‘multipolar scenario’, a situation in which there exist a number of different superintelligences with contradicting values. And indeed, there are many smart people who think about the dangers of these selection pressures to a sufficiently advancd civilization.
So, malthusian pressures on biological systems are unlikely to explain the apparent lack of spacefaring civilizations. On the other hand, malthusian pressures on technologically optimized digital entities (possibly an obligate stage of civilization) may be much more of a threat, perhaps even one deserving the name ‘Great Filter’.
This filter applies even before they invent technology. Brains use lots of energy and development time. This is typically selected against. Therefore most organisms only evolve the minimum amount of intelligence they need. And human level intelligence is never an advantage in most environments.
So you need some really weird set of conditions to create an environment that selects for high intelligence, and doesn’t select too strongly against energy efficiency or development time. I don’t know what these conditions are, but they only occurred once on Earth, over hundreds of millions of years. This suggests these conditions occur very rarely, and we might just be very lucky.
I think a too easy reproduction mechanism means not evolving intelligence. The selective pressure for human intelligence could not have came from the environment or else many species would be similarly intelligent like how many species can fly. It was some sort of a competition inside our species, probably sexual. And when reproduction is easy, sexual competition is not so tight. In fact, the most likely answer is that the runaway explosion of intelligence that resulted in us must be probably a mutually reinforcing process: intelligence made reproduction harder, hence more sexual competition, hence more pressure for intelligence.
How did intelligence make reproduction harder? Through big heads making childbirth harder. Frankly I don’t know why didn’t evolution just came up with the idea of giving women gigantic hips and large vaginas, but what happened instead is that babies are born far too prematurely so that their head size is not too big, and thus require a huge amount of care and investment after birth. This, postnatal maternal investment, then intensified sexual competition and thus pressure for more intelligence.
This really rules out the external eggs.
A currently popular theory (at least, at the pop sci level, I don’t know how it is regarded by actual scientists) is that intelligence snowballed due to social competition of all against all—an arms race. The smarter people are, the better they can detect lies, but also the smarter they are, the better they can get away with lying. Everyone needs to be as smart as possible just to keep up, until the process runs into a limit, such as the size of the birth canal. Expanding that by widening the pelvis adversely affects mobility.
But that looks like a just-so story. Why did that process happen to humans and not chimpanzees? To which one answer might be: It could have happened to a different branch of the primates, it just chanced to happen to our ancestors first. Someone had to be first, and they’re the only ones smart enough to be having this conversation. Once started, the process was so fast that every other creature that didn’t reach take-off has effectively stood still, and in the modern world they stand no chance except by our permission.
I think it is not a just-so story, it largely predicts everything it should and fails to predict everything it shouldn’t. Runaway processes require feedback, I think this is the key. Look for the thing that intelligence made harder. That thing is birth and babycare. Intelligence makes it hard, this causes X to be stronger, and X causes more intelligence, that is the feedback process. What could X be? Sexual competition. More: http://lesswrong.com/lw/mcj/open_thread_jun_15_jun_21_2015/chju
Because a wide pelvis is mechanically worse for bipedal locomotion. You need to be able to run away from lions in between popping out kids...
I’m not sure about that. Be very skeptical of claims that something evolved due to sexual selection, it tends to be the default explanation lazy evo-psy people reach for when they can’t immediately think of a better explanation.
Wait, what? What are even the alternatives? The only alternatives are environmental pressure—food, predators etc. But such an environmental pressure affects a lot of species at the same time and for this reason, most traits in the animal kingdom have the expected normal distribution. Such as the ability to swim amongst mammals—many can swim a little, some better, and a few really well. Yet the distribution of intelligence in species does not follow normal distribution. Humans are far, far ahead from the species in the second places (apes, dogs, dolphins). If it was environmental pressure, adult chimpanzees were basically like retarded humans or humans who are stuck at the mental capabilities of a 10 year old. Bonobos would be flipping burgers at McD. (OK some people do claim that certain dogs have the IQ of a 5 year old human but it is really a stretch. Their communication ability and suchlike does not even compare.)
Being so far ahead can mean only one thing—the selective pressure MUST have came from withing the hominid species, not from the environment.
But what could hominids compete for? Not food. Food is also an environmental variable and if we don’t see e.g. gorillas compete a lot of for food, we should assume there was enough around.
This gives really only one option left.
Factor in that runaway processes MUST have, I will risk a “per definition” here even though it is not math, a feedback element. Whatever X-factor (lol) pressed humans to get more intelligent, must have been made worse by humans getting more intelligent, so it exerted even more and more pressure or how else could it be such a runaway process.
This is useful, because it suggests we should just look at what was made worse by the evolution of intelligence and we found the feedback factor. And the answer is obvious: reproduction. Childbirth, the physical process of getting the head out, and the babycare.
In my mind it is a fairly strong set of evidence and it not only predicts everything we want it to predict here, it also reliably fails to predict everything it shouldn’t and that is what a good theory should do.
For example, if food scarcity was a selective factor, we would have iron stomachs, able to eat everything. In reality, we have shit for stomach, we need to cook our food, we cannot digest most leaves nor grass—the most available resource! - we get ill easily and so on. Sure, human diets have a wide variance, but it seems we are really picky eaters, going for the special stuff, not the easy available stuff: leaves, grass, carcass. What does that suggest? It suggests no food scarcity.
Or say predators. Most animals try to protect themselves from predators with claws and fangs. Again, we have crap in that department. If there was any serious pressure there, we’d kept these around.
So what kind of environmental pressure is left, really?
I am also surprised that it is you who say it, because I had the impression you give some credibility to the set of views that are sometimes called red pill or manosphere. They are 100% based on sexual selection shaping human nature, without that they haven’t any chance of getting anything right.
This is what I mean by lazy evo-psych. You dismiss the alternatives using hand waving logic and assert that it must be sexual selection even though one could dismiss sexual selection just as easily by hand waving. Let’s go through you comment piece by piece.
And different species respond to [edit:similar] environmental pressures in different ways.
This is the only part of your comment that might be worthwhile, assuming you have data about the traits actually being normally distributed and are not just doing the lazy statistician thing of assuming all distributions are normal. Even then, it’s not clear that this doesn’t apply to traits that are the result of sexual selection.
I’m not sure what the distinction between environmental and intraspecies selection pressure that you’re trying to make here is supposed to be.
First yes gorillas compete for food. Second the claim that “there was enough around” is silly. If there’s enough food around, a species’ population generally increases until it either reaches the Malthusian limit or it’s stopped by some other factor, e.g., disease.
I’m trying to parse the above argument as anything other then a complete non sequitur and failing. Perhaps you can help: Suppose we have a hominid of above average intelligence, how does the above translate into a causal mechanism that leads to him having more decedents?
In particular if sexually selection is responsible for intelligence, we would expect highly intelligent people to be highly sexually desirable especially when considerations like resource constraints are removed from the picture. We now live in a highly prosperous time, and to say that nerds aren’t sex gods would be a gross understatement.
Why? Yes, iron stomachs are one way to adept to food scarcity, they aren’t the only way.
More interestingly we can cook food, i.e., we can partially pre-digest our food externally, which is another way to adept to food scarcity.
It’s actually incredibly hard to digest leaves and grass, that’s why cows, etc., need four stomachs.
No most animals protect themselves by being really good at running away, or having a hard shell/hide. In fact nearly all animals that have claws or fangs are predators themselves and use their claws and/or fangs for hunting.
Just because some aspects of human nature are shaped by sexual selection doesn’t mean all aspects are.
Food is a resource outside the species, sex is a resource inside the species.
Wait a bit here. We are not talking about going from 120 IQ to 140 increases the number of descendants. We are talking about going from 80 to 100 does. On that level the distinction is not between super smart nerds vs. everybody, but more being able to handle normal things vs. shooting yourself in the foot all the time.
Of course, that environment, that social environment was far simpler. Still if you ever hang out with simpler people (e.g. what in the UK is called a flat roof pub ) it is typically the 80 IQ guy who insists on fighting some other guy for no good reason whatsoever and it is the 100 IQ friend who is telling him don’t be an idiot he is twice your size and did time for stabbing someone. Or you see how dumber criminals get busted on really trivial mistakes—if all you have is tribal customs instead of laws it probably still works the same way. Or, maybe, the difference between a 80 IQ and 100 IQ tribal warrior is largely that the later does not think “we are the awesomest” is a good enough reason to attack a tribe that has three times as many warriors. In short, while really high IQ does not help with reproduction much, really low IQ provides excellent opportunities to shoot oneself in the foot in a competitive social environment. What we today consider average IQ simply translates to a hominid who is a bit cautious and can assess when to be brave and when to be a coward. Not some super nerdy level of intelligence.
Even today, I would say there is an IQ threshold below which people have lower number of children. I don’t think Idiocracy the movie got it exactly right. While the dumbass having 4 kids with 4 different single moms is a popular trope, in really the really dumb guys tend to go in and out of prison or be really ridiculous at pick-ups because they cannot think of anything to say really beyond “nice tits”. The charming simpleton with the 4 different single-moms is actually going to be somewhere closer to the average IQ.
Sure, a peacock having a REALLY huge tail may be detrimental to its reproductive success because it cannot even go through a mating dance routine maybe, but that is no evidence wrt to the average sized one not being more useful than the small one. Same for intelligence.
Note that none of your examples are cases of sexual selection.
Those don’t necessarily interfere with each other.
A REALLY huge tail is detrimental because it makes the peacock more likely to be eaten by a tiger, i.e., non-sexual selection. If peacocks were placed in an environment without tigers females would chose even larger tails. Heck they’ve done experiments where they glued on extra tail feathers to give a lucky peacock an even larger tail, the result being that females preferred those males to any males with a natural tail.
Heck consider an actual example of sexual selection in humans: Men like women with large breasts. Notice how common ridiculously large breasted women are in everything from advertizing to anime to video games. Heck in ancient times people would worship multi-breasted fertility goddesses. Contrast that with the portrayal of smart men, who must be given an actual “sexy” trait (like being rich or a badass) for women to accept them as “sexy”. For example, Q’s gadgets contribute to James Bond’s (not Q’s) sex appeal even though he’s not the one developing them.
Sexual selection doesn’t end at being attractive. It could be everything from killing competing suitors to making sure kids have a good career. Just as every organ is a reproductive organ, drawing the borders of sexual selection is hard. Everything cashes out in reproduction, where I try to draw the line is that the survival of individual animals against the forces outside the population is not, so getting food and getting away from predators is not. But pretty much everything inside the population is. But even getting a lot of food can be an aspect of it… crap. The point is that the traditional/popular views of evolution tend to be “survivalist” and basically this intra-population competition / sexual selection stuff is largely everything else that it is not directly survivalist but is about competition for things beyond the survival of the individual. Be that sexual partners or childrearing.
And yes, in this sense Mr. Dumb taking a knife to the heart in a pub and his girlfriend hooking up with someone else is an example of this intra-species competition...
Yes, you could define “sexual selection” that generarly. However, I don’t think a terms that refers to everything is particularly useful.
Yes, but I wouldn’t call that sexual selection unless the fight was specifically over the girlfriend.
More generally, you can imagine a lot of failure modes where an alien species evolves to become intelligent, but cannot build technological civilization because it cannot achieve large scale social cooperation.
E.g. imagine a society where human brains evolved just a little bit differently and >90% of population are dyslectics. This very obviously wouldn’t matter until about the time proto-writing changed into true writing, i.e. after urban development and proto-states. But then, such a civilization is trapped.
There’s actually some evidence humans have made some adaptions to be better at reading, but I can’t find a source.
Being able to read would be a valuable advantage and after tens of thousands of years of evolution, more and more people could read.