How much selection pressure can you get if you’re only selecting at the level of the gamete, and not at the level of the person or the gene? For example, given a man and a woman, suppose that you looked at 1 million of the man’s sperm and picked the best (according to whatever criteria you’re using), and you picked the best out of 100 of the woman’s eggs, and you mated them. If that was how everyone reproduced, would that provide enough selection pressure to satisfy whatever goals you have for the gene pool?
If so, then a eugenics program would not need to restrict who breeds and it could probably get by with very little coercion. I described some options in more detail in a comment at Yvain’s blog, but in the right cultural context all you’d need to do is have the reproductive technology that allowed for this kind of genetic screening, and get most people to use it instead of old-fashioned reproduction. The government could make genetic screening the norm by subsidizing reproductive technology to make it free to everyone and by enforcing universal birth control as the default state (so that a person would have to opt in to become capable of reproducing the standard way). Parents’ choices (and time) would take care of the rest. It’s easy to imagine a culture where most parents would go the medical route instead of opting for the standard genetic roulette, and where they’d direct a decent amount of their selective pressure towards attributes like intelligence.
This system is optimized for being unobjectionable, rather than for the most effective genetic selection. It could operate under the banner of feel-good liberal labels, like reproductive rights (giving people more control over whether/when/how they reproduce), preventing unwanted pregnancy (by making fertility opt-in), egalitarianism (equal access to reproductive technology), and parental choice (over their child’s genes).
If it isn’t selective enough, the next step would be to operate at the level of the gene, using fancier technology to alter specific genes. As Xachariah describes, that could also be voluntary.
How much selection pressure can you get if you’re only selecting at the level of the gamete, and not at the level of the person or the gene? For example, given a man and a woman, suppose that you looked at 1 million of the man’s sperm and picked the best (according to whatever criteria you’re using), and you picked the best out of 100 of the woman’s eggs, and you mated them. If that was how everyone reproduced, would that provide enough selection pressure to satisfy whatever goals you have for the gene pool?
You can get a lot of pressure. Steve Hsu in one of his slides on BGI (which I can’t be arsed to look up) gives a quick estimate that you can get maybe half a standard deviation per generation at ordinary embryo fertilization numbers.
This is plausible if you think about it in a very rough sort of way.
We know IQ is something like 50% genetic, right? If I make 5 embryos for a couple, that’s like them having 5 kids; if you saw a normal family of 5 kids, how much smarter than the average of the 5 will the smartest of the 5 be? At a guess, 20 points sounds too much to often happen, but 5 points sounds way too little, so maybe 15 points; we said half the variance was genetic, so that suggests the underlying genes can claim credit for 7-8 of the excess points. If the couple has only 1 kid and the embryo with the best genetic scores is picked, then the genetic base will go up by ~7 points. And as it happens, one standard deviation is often 15 points so 7/15=0.5 standard deviations. Rinse and repeat for the next generation.
EDIT: http://duende.uoregon.edu/~hsu/talks/ggenomics.pdf Gives an example of selection on 100 alleles etc for an estimate of ~0.2SD per generation in that scenario; the more alleles you select on, presumably the higher you get per cycle.
How much selection pressure can you get if you’re only selecting at the level of the gamete, and not at the level of the person or the gene? For example, given a man and a woman, suppose that you looked at 1 million of the man’s sperm and picked the best (according to whatever criteria you’re using), and you picked the best out of 100 of the woman’s eggs, and you mated them. If that was how everyone reproduced, would that provide enough selection pressure to satisfy whatever goals you have for the gene pool?
If so, then a eugenics program would not need to restrict who breeds and it could probably get by with very little coercion. I described some options in more detail in a comment at Yvain’s blog, but in the right cultural context all you’d need to do is have the reproductive technology that allowed for this kind of genetic screening, and get most people to use it instead of old-fashioned reproduction. The government could make genetic screening the norm by subsidizing reproductive technology to make it free to everyone and by enforcing universal birth control as the default state (so that a person would have to opt in to become capable of reproducing the standard way). Parents’ choices (and time) would take care of the rest. It’s easy to imagine a culture where most parents would go the medical route instead of opting for the standard genetic roulette, and where they’d direct a decent amount of their selective pressure towards attributes like intelligence.
This system is optimized for being unobjectionable, rather than for the most effective genetic selection. It could operate under the banner of feel-good liberal labels, like reproductive rights (giving people more control over whether/when/how they reproduce), preventing unwanted pregnancy (by making fertility opt-in), egalitarianism (equal access to reproductive technology), and parental choice (over their child’s genes).
If it isn’t selective enough, the next step would be to operate at the level of the gene, using fancier technology to alter specific genes. As Xachariah describes, that could also be voluntary.
You can get a lot of pressure. Steve Hsu in one of his slides on BGI (which I can’t be arsed to look up) gives a quick estimate that you can get maybe half a standard deviation per generation at ordinary embryo fertilization numbers.
This is plausible if you think about it in a very rough sort of way.
We know IQ is something like 50% genetic, right? If I make 5 embryos for a couple, that’s like them having 5 kids; if you saw a normal family of 5 kids, how much smarter than the average of the 5 will the smartest of the 5 be? At a guess, 20 points sounds too much to often happen, but 5 points sounds way too little, so maybe 15 points; we said half the variance was genetic, so that suggests the underlying genes can claim credit for 7-8 of the excess points. If the couple has only 1 kid and the embryo with the best genetic scores is picked, then the genetic base will go up by ~7 points. And as it happens, one standard deviation is often 15 points so 7/15=0.5 standard deviations. Rinse and repeat for the next generation.
EDIT: http://duende.uoregon.edu/~hsu/talks/ggenomics.pdf Gives an example of selection on 100 alleles etc for an estimate of ~0.2SD per generation in that scenario; the more alleles you select on, presumably the higher you get per cycle.