The Nature article is a bit of a reach...
They got it right with this: In evolutionary terms, having a long life isn’t as important as having a reproductively fruitful one, with many children who survive into adulthood and birth their own offspring. So harmful mutations that exert their effects after reproductive age could be expected to be ‘neutral’ in the eyes of evolution, and not selected against.
They should have just stopped there. Way too many "other" factors impact post-reproductive longevity... including basic improvements in the social "safety nets" that didn't used to care for the elderly the way they do now... and the advancement of medicine, of course. Routine heart surgery... routine basic medical care... better dentistry... water that isn't contaminated... etc. All of that stuff isn't really making people genetically more prepared to live longer... rather than keeping them alive longer, with what they have, in spite of the other factors in the environment that likely would have done most of the elderly in a lot sooner than happens now, a generation ago.
The rest... is just common sense. If there are mutations that seriously disadvantage reproduction... they will tend to be sorted out, more and more rapidly in the degree they're more more recognizable by potential mates as being disadvantageous... or just prevent success at a high enough rate that social support isn't able to overcome the obstacles imposed. But, the fact of recessives and carriers... means that "minor" things (like sickle cell or cystic fibrosis... which are not minor if you have them... but are minor in genetic terms of carriers surviving just fine)... just aren't going to be easily sorted out that way...
The article doesn't point it out... but there is a massive new potential emerging there... resulting precisely from the growing prevalence in our awareness and use of genetics... as people now can make more informed choices about reproduction... and opt to not propagate known genes that carry known risks...
As gene editing technology advances... I don't think you will be able to stop people using it.
Within a generation or two we could be spawning nothing but superior athletes who do rocket science and physics for their hobbies... but my guess is they still won't be able to balance the budget or get rid of the national debt... ;<)
I think growing awareness of genetics... begins to accelerate change... at the pace that people become aware enough to begin to take more deliberate control over their risks and rewards in reproductive output.
C sections... are likely to have growing impact... in the interplay between the size of women's hips and the ability of offspring to survive birth... as more big headed babies make it past the trial of birth over time. What is there that will stop that trend in birthing what otherwise would tend to be non-viable babies... as long as we do have and sustain the medical capacity to enable it ?
I think this is probably wrong, though: The latest genetic evidence makes Pritchard think there is an evolutionary trade-off between fertility and longevity, which had previously been studied only in other animals. “To actually find this in humans is really pretty cool,” he says. “I think it's a really nice study.”
The problem there is sorting out the non-genetic... or already intrinsic... elements in longevity which are less about existing genetic potential... and more about more about how the existing potential is expressed with variation depending on the circumstances.
We already know that "fat" years... good times in the economy... shortens people's lives... because eating too much is bad... and hard times in the economy... prolong life... because that triggers genetic potential that seeks to preserve potential rather than accelerate generations... Not everything in our genetics is about individual potentials. Fat times advantage the population by killing us off faster in fat times... so that more genetic mingling occurs faster... while lean times make us live longer... when the environmental imperative works with our existing genetics on a population level... to try to ensure our genetic potential doesn't die out... |
