>I left this example for last because I do not yet have a specific example of this phenomenon in humans, though I suspect that some exist.
**There’s plenty of traits that fit the bill here, they’re just not things people would ever think of as being negative.**
Most such traits exist because of sexual selection pressures, the same reasons traits as negative sum as peacock feathers can persist. Human traits which fall under this category (or at least would have in the ancestral environment):
Traits like incredibly oversized penises for a great ape, secondary sexual traits like permanent breasts, etc are almost perfectly analogous to peacock feathers. Plenty of other aspects of human biology may also have been driven by sexual selection, but it’s harder to determine. For instance birds have voice-boxes which are vastly more complex than can be justified without sexual selection. Similarly it’s quite plausible that humans have far more vocal range/ability than would be justified just for the purpose of communication.
Eye and hair colors other than the default brown/black are probably mostly zero sum. Since many mutations leading to other hair/eye colors seem to have spread implausibly fast given their marginal to nonexistent benefits. Of course given such traits seem exotic when they are rare it makes sense they would spread through sexual selection.
Height fits the bill, since it provides a negative sum social advantage, at the cost of placing more toll on the body and requiring more calories. In the ancestral environment heigh also gave an advantage to combat prowess, which is likely to be partly responsible its success (and still negative sum).
If you buy the theory that higher intelligence among hominids was driven by sexual selection beyond a certain point then it also fits the bill. Since within this model the advantage of intelligence would be negative sum in the ancestral environment past a certain point. With it letting you be more popular, while forcing the whole population to evolve more energetically costly brains which provided diminishing returns to practical things like hunting prowess.
Many irrational aspects of human psychology fit the bill quite well, after all not getting socially ostracized was far more important than having accurate beliefs.
Anyway my point is such zero and negative traits are actually quite common, and generally attributable to social signaling. Making humans in many respects comparable to peacocks when you take a step back. The fact such traits are driven by sexual selection is also the same reason engineering them away (at least where they’re still not positive sum in the modern world) will never be popular.
People would never endorse the prospect of engineering people to be: short, very intelligent and rational but poor at navigating status games, have tiny dicks and breasts, etc.
I’ve spent a fair bit of time thinking about the potential implications of a soft or hard ban on these types of zero sum traits. You’re probably right that people wouldn’t accept mandated downgrades from their current possession of these zero sum traits (shorter, smaller breasts etc), but it seems plausible that at some point we might put a cap on how extreme we’re willing to let people engineer themselves.
But historical precident has given me pause. One can imagine that the gigantic benefits to the species as a whole of increased intelligence would not at all have been apparent for most of human history. Might we accidentally ban a trait that appears to be zero sum but actually has massive positive externalities that we simply don’t foresee? That’s one of the things I’m worried might happen with these types of bans.
Of course there are probably even bigger risks if we simply allow unlimited engineering of these sorts of zero sum traits by parents thinking only of their own children’s success. Everyone would end up losing.
>Of course there are probably even bigger risks if we simply allow unlimited engineering of these sorts of zero sum traits by parents thinking only of their own children’s success. Everyone would end up losing.
The negative consequences of a world where everybody engineers their children to be tall, charismatic, well endowed, geniuses are almost certain to be far less than the consequences of giving the government the kind of power that would allow them to ban doing this (without banning human GM outright which is clearly an even worse outcome).
I’m thinking of something like a fitness trap scenario, where competition to maximize zero sum traits degrades some other key trait in an irreversible way. Not that it would literally be irreversible, but that the degradation of such a trait (perhaps we find a gene that makes you very attractive but dumber) would make the next generation even more likely to sacrifice that key trait etc etc in a vicious cycle.
I’m thinking here of the Irish Elk, a huge species of deer whose competition for larger antler size drove it to extinction.
Though I agree with you that the danger of banning genetic modification would be much, much greater than the danger of this kind of sexual selection induced extinction.
EDIT: After reading the article I linked it looks like there is actually controversy about whether large antlers drove the Irish Elk extinct. The real cause may have been a combination of a reduction in food an predation. So perhaps that’s not the best example for the wisdom of banning zero sum trait selection.
An irish elk/peacock type scenario is pretty implausible here for a few reasons.
Firstly people care about enough different traits that an obviously bad trade like attractiveness for intelligence wouldn’t be adopted by enough people to impact the overall population.
Secondly for traits like attractiveness low mutation load is far more important than any gene variants that could present major tradeoffs. So just selecting for less mutation load will improve most of the polygenetic traits people care about.
Ultimately the polygenetic nature of traits people care the most about just doesn’t create much need or incentive for the kinds of trade offs you propose. Such tradeoffs could only ever conceivably be worthwhile in order to reach superhuman levels of intelligence (nothing analogous exists for attractiveness) which would have obvious positive externalities.
Every time I read one of Scott Alexander’s posts I lament my own writing abilities. He’s said everything I want to say about the tradeoffs in genetic engineering with fewer words and in a more comprehensible manner.
I guess my ultimate aim in writing these posts is to convince myself and others that genetic engineering is not only desirable but possible in the near future. I guess maybe what I should be focusing on is less persuasive writing and more HOW to do it.
Though part of me despairs at the possibility of us ever pursuing such a path. Cloning is banned in nearly every country in the world in which it might be possible to create clones. This is ostensibly because cloned mammals have a much higher rate of birth defects, yet so far as I can tell there is no effort being made to reduce the likelihood of such errors. Instead it seems like the current technical problems are being used as an excuse to stop research on how to make cloning safer.
>I left this example for last because I do not yet have a specific example of this phenomenon in humans, though I suspect that some exist.
**There’s plenty of traits that fit the bill here, they’re just not things people would ever think of as being negative.**
Most such traits exist because of sexual selection pressures, the same reasons traits as negative sum as peacock feathers can persist. Human traits which fall under this category (or at least would have in the ancestral environment):
Traits like incredibly oversized penises for a great ape, secondary sexual traits like permanent breasts, etc are almost perfectly analogous to peacock feathers. Plenty of other aspects of human biology may also have been driven by sexual selection, but it’s harder to determine. For instance birds have voice-boxes which are vastly more complex than can be justified without sexual selection. Similarly it’s quite plausible that humans have far more vocal range/ability than would be justified just for the purpose of communication.
Eye and hair colors other than the default brown/black are probably mostly zero sum. Since many mutations leading to other hair/eye colors seem to have spread implausibly fast given their marginal to nonexistent benefits. Of course given such traits seem exotic when they are rare it makes sense they would spread through sexual selection.
Height fits the bill, since it provides a negative sum social advantage, at the cost of placing more toll on the body and requiring more calories. In the ancestral environment heigh also gave an advantage to combat prowess, which is likely to be partly responsible its success (and still negative sum).
If you buy the theory that higher intelligence among hominids was driven by sexual selection beyond a certain point then it also fits the bill. Since within this model the advantage of intelligence would be negative sum in the ancestral environment past a certain point. With it letting you be more popular, while forcing the whole population to evolve more energetically costly brains which provided diminishing returns to practical things like hunting prowess.
Many irrational aspects of human psychology fit the bill quite well, after all not getting socially ostracized was far more important than having accurate beliefs.
Anyway my point is such zero and negative traits are actually quite common, and generally attributable to social signaling. Making humans in many respects comparable to peacocks when you take a step back. The fact such traits are driven by sexual selection is also the same reason engineering them away (at least where they’re still not positive sum in the modern world) will never be popular.
People would never endorse the prospect of engineering people to be: short, very intelligent and rational but poor at navigating status games, have tiny dicks and breasts, etc.
I’ve spent a fair bit of time thinking about the potential implications of a soft or hard ban on these types of zero sum traits. You’re probably right that people wouldn’t accept mandated downgrades from their current possession of these zero sum traits (shorter, smaller breasts etc), but it seems plausible that at some point we might put a cap on how extreme we’re willing to let people engineer themselves.
But historical precident has given me pause. One can imagine that the gigantic benefits to the species as a whole of increased intelligence would not at all have been apparent for most of human history. Might we accidentally ban a trait that appears to be zero sum but actually has massive positive externalities that we simply don’t foresee? That’s one of the things I’m worried might happen with these types of bans.
Of course there are probably even bigger risks if we simply allow unlimited engineering of these sorts of zero sum traits by parents thinking only of their own children’s success. Everyone would end up losing.
>Of course there are probably even bigger risks if we simply allow unlimited engineering of these sorts of zero sum traits by parents thinking only of their own children’s success. Everyone would end up losing.
The negative consequences of a world where everybody engineers their children to be tall, charismatic, well endowed, geniuses are almost certain to be far less than the consequences of giving the government the kind of power that would allow them to ban doing this (without banning human GM outright which is clearly an even worse outcome).
I’m thinking of something like a fitness trap scenario, where competition to maximize zero sum traits degrades some other key trait in an irreversible way. Not that it would literally be irreversible, but that the degradation of such a trait (perhaps we find a gene that makes you very attractive but dumber) would make the next generation even more likely to sacrifice that key trait etc etc in a vicious cycle.
I’m thinking here of the Irish Elk, a huge species of deer whose competition for larger antler size drove it to extinction.
See here: https://www.nationalgeographic.com/science/phenomena/2008/09/03/the-allure-of-big-antlers/
Though I agree with you that the danger of banning genetic modification would be much, much greater than the danger of this kind of sexual selection induced extinction.
EDIT: After reading the article I linked it looks like there is actually controversy about whether large antlers drove the Irish Elk extinct. The real cause may have been a combination of a reduction in food an predation. So perhaps that’s not the best example for the wisdom of banning zero sum trait selection.
An irish elk/peacock type scenario is pretty implausible here for a few reasons.
Firstly people care about enough different traits that an obviously bad trade like attractiveness for intelligence wouldn’t be adopted by enough people to impact the overall population.
Secondly for traits like attractiveness low mutation load is far more important than any gene variants that could present major tradeoffs. So just selecting for less mutation load will improve most of the polygenetic traits people care about.
Ultimately the polygenetic nature of traits people care the most about just doesn’t create much need or incentive for the kinds of trade offs you propose. Such tradeoffs could only ever conceivably be worthwhile in order to reach superhuman levels of intelligence (nothing analogous exists for attractiveness) which would have obvious positive externalities.
https://slatestarcodex.com/2016/05/04/myers-race-car-versus-the-general-fitness-factor/
Every time I read one of Scott Alexander’s posts I lament my own writing abilities. He’s said everything I want to say about the tradeoffs in genetic engineering with fewer words and in a more comprehensible manner.
I guess my ultimate aim in writing these posts is to convince myself and others that genetic engineering is not only desirable but possible in the near future. I guess maybe what I should be focusing on is less persuasive writing and more HOW to do it.
Though part of me despairs at the possibility of us ever pursuing such a path. Cloning is banned in nearly every country in the world in which it might be possible to create clones. This is ostensibly because cloned mammals have a much higher rate of birth defects, yet so far as I can tell there is no effort being made to reduce the likelihood of such errors. Instead it seems like the current technical problems are being used as an excuse to stop research on how to make cloning safer.