Well at about 4:26 in the video he talks about environmental selection, and then at 4:53 jumps to talking about mating specifically. Regards to the latter, his point is simply: more people are mating, therefore bad genes survive. This way he is committing two mistakes:If you assume he knows about sexual selection but is focused on pressures to survival, and that he understands there are still pressures to surivival but they are greatly reduced, does he make sense or do you still think what he's saying is flawed?
To see how sexual selection can work even when everyone pairs up into couples, we need a thought experiment. [...]
Each individual wants to attract the highest-
fitness mate they can, because they want the best genes for their offspring. There will be a sorting process. Probably, the highest- fitness male will court the highest-fitness female first. If she is sensible, she will accept him, and they will pair off, leaving the rest of the tribe to sort themselves out. The second-highest-fitness male is disappointed. He wanted the highest-fitness female, but could not attract her. He must settle for the second-highest- fitness female. She is also disappointed, because she wanted the best male. But she settles for male number two, because she cannot do any better.
[...]
The result will be that mated pairs will correlate highly for
fitness. If height correlates with fitness, they will be of similar height. If intelligence correlates with fitness, they will be similarly bright. If facial attractiveness correlates with fitness, they will be similarly beautiful. This is basically what we see in modern human couples: a fairly high degree of "assortative mating" for fitness indicators.
[...]So, the babies of higher-fitness couples will inherit higher-fitness genes. By definition, higher fitness leads to a better chance of surviving to sexual maturity. The offspring of male number one and female number one may have a very high chance of surviving. The offspring of the lowest-fitness male and the lowest-fitness female may only have a very low chance of surviving. By the time the babies' generation grows up, there will be more surviving offspring of high-fitness parents than of low- fitness parents. In fact, the babies' generation will have a higher average fitness than their parents' generation did.
They cannot prosper via sexual selection, because sexual selection results in assortative mating. Just because a gene manages to reproduce doesn't mean it will prosper.less environmental selection means weak genes still have a chance to prosper via sexual selection
actually lower IQ strongly correlates with greater rates of reproduction so if we want to go down that route of argument, they're prospering
*Serac's hatred of welfare intensifies*
the impact of assortative mating is rather irrelevant to my point in any case. people that would have died, now easily reproduce. penicillin allows people with weaker immune systems to survive and prosper, as do numerous other cures and methods of prevention
sicklier and sicklier is becoming the norm, offset by medicine
actually lower IQ strongly correlates with greater rates of reproduction so if we want to go down that route of argument, they're prospering
*Serac's hatred of welfare intensifies*
the impact of assortative mating is rather irrelevant to my point in any case. people that would have died, now easily reproduce. penicillin allows people with weaker immune systems to survive and prosper, as do numerous other cures and methods of prevention
sicklier and sicklier is becoming the norm, offset by medicine
Not gonna explain a 4th time why this argument is flawed.
@redbaron
Is is really a 'strong' correlation? That's has a specific statistical meaning in the social sciences (R>.69), basically meaning that half of all variance is explained by the correlation. That would be... really concerning.
That's a fair point. One is getting into a more abstract definition of genetic quality in that case, though. For example if fertility can be considered a trait, and infertile people can use technology to reproduce, it means they are well-adapted to an environment where that technology exists. But that's the case for any trait – there's always a risk of a change in environment that will make the previous traits maladapted. For example if we get a new ice age, a lot of people will be maladapted to the change.ell versed in this stuff, but it seems to me like his point is not just that more people are mating therefore there is a decline. My interpretation of his point is that we are now controlling a large number of our selective pressures, and the refined evolutionary traits we had developed to address these pressures are going to disappear much faster than they were acquired due to the nature of unselected mutation.
His examples were fertility and eye-sight, two things we overcome the need for through technology.
What I take away is that he thinks traits that were hard to develop will disappear over time if they are no longer selected for. Not that there is no selection taking place. He doesn't talk about assortative mating or whatever else because he's not concentrating on the selection that does take place.
Essentially we now decide what 'fitness' means due to our control over the environment, and this comes at the cost of no longer meeting old fitness requirements. And this is okay for so long as we have the technology to compensate, but if ever we don't, we're going to have a harder time.
Am I missing something?