I have a theory that if you could for several generations outlaw human reproduction before the age of oh say 40, then for subsequent generations before 50, and so on for hundreds or more likely thousands of years, you could extend the “natural” lifespan of mankind. (Based on the theory that aging has been “allowed” by natural selection because it tends to happen, by definition, AFTER the genes have already passed on, so does not interfere directly with reproduction.) Now, obviously there’s no way this could ever happen. (Or at least not in my lifetime, snerk.)
What impossible experiments would you like to see happen?
There is growing evidence that sperm from older men is not as healthy as sperm from younger men and sperm samples from older men tends to have more defective sperm. I’m pretty sure if you started pushing the ages to 60+ the level of birth defects or physical problems arising later in life would probably rise substantially negating any age selection benefits.
Not to mention the fact that children born to older women are significantly more likely to have birth defects. I think the OP’s plan is not a sound one.
China offers many possibilities. Get all the people in China to stand on a stool at one time and then jump. Make them all stand in a line and see if the line ever ends or it keeps growing as more Chinese people are born. Have them dig a hole through the center of the earth and see if it ends up in my back yard . . .
You’re talking about current older women; you’re talking about exactly the issues that this “experiment” would address and eliminate.
One of the MANY reasons that this experiment would be utterly unworkable is that OF COURSE there would be MANY more infant deaths to start with, thus eventually eliminating those traits.
Again, the experiment proceeds gradually: 40 years old, then after several centuries, 50 years old, etc. Eventually weeding out the people–even if they’re the majority–who produce unhealthy babies at an older age.
Again, this experiment would be *specifically *to weed out the traits you and astro point out. Those traits are precisely the reason for the experiment.
Ah, but after how many generations? Perhaps the genetic predisposition toward those types of birth defects might be culled entirely within a century or two.
ETA: or what lissener said.
But it will all end in tears, you know. Yes, they’re living longer, but after a few centuries you’ve got the Coms fighting the Yangs and mangling the Declaration of Independence, so what’s the point?
Since we’re talking eugenics experiments, why not do like Heinlein wrote about in his Lazarus Long novels? In them there was a secret society founded by Ira Howard that reproduced only with people that had all four grandparents live to be over 100 years old.
I remember reading about an experiment like the OP but with house flies. It took about ten generations for noticibly longer-lived flies to manifest. If this was true for humans, I guess about 400 years for the geriatric marvels to appear. One might try to speed things up, though by selective breeding of folks with the sought after traits.
You’re right about all of this, with regard to births. The problem is that we don’t know if later fertility is linked to a longer lifespan, so what exactly will this experiment tell us? It selects for later fertility but not for long lives, and there’s no way to ethically test the link. (What will you do, force people to keep trying to have babies after they normally would, then see how long they live?) What you’d need to do to select for longer lived people is to either kill off the babies that don’t come from people who live well into their 90s, then 100s, and so on, OR to only allow those people to breed who have evidence of long-lived ancestors.
What I’d like to know? How much of “gender differences” is ingrained and how much is socialized. There’s already a decent amount of evidence that shows that even young school children act differently when in mixed gender versus single gender groups, suggesting that the sexes affect each others’ socialization even at a young age. In addition, even when you isolate people as adults they show less gender stereotyped behavior. I’d like to raise some kids in completely segregated groups and see what happens. I bet the differences are smaller than most of us think. Of course, this is completely unethical.
That’s one of the questions I devised this experiment to answer.
Here’s my thinking:
There’s obviously some variability in when the effects of aging start to manifest in different people. If you’re one of the people in whom those effects manifest early in life, then in you’ve reproduced very young, before they manifest, you’ll pass on those early-manifesting genes. If however you’re prevented from reproducing until those early-manifest genes, uh, manifest, then the early manifestation of aging might itself interfere with your reproduction. By delaying reproduction we’ve made early manifestation of aging counter adaptive. Early reproduction renders it irrelevant.
If we keep pushing back reproduction, then people whose aging effects manifest later in life will tend, so’s the theory, to reproduce more healthy children than those who manifest earlier.
Graduated delay–later and later–over subsequent generations, for long enough (again, acknowledged centuries if not more) will–theory–tend to favor the people who manifest aging effects later in life. Perhaps even eventually selecting for the ability to indefinitely self-repair the body: physical immortality.
(Obviously that would raise a whole host of new problems, the most obvious one being overpopulation, but still, this is just a thought experiment.)
But aging and reproduction aren’t the same thing. You could be selecting for people with more eggs, or with slower ovulation cycles and a therefore longer period of reproductive activity, rather than a later onset of aging. It seems like your experiment would merely select for people who remained fertile throughout their natural lifespan rather than extending that lifespan. It’s not efficient to select for something indirectly, assuming a link between two things that may not be linked.
Rather than push back the age at which you are allowed to reproduce, just take egg and sperm from people at the peak of healthy production and freeze it. Once the donors have reached a target age naturally. Or demonstrated some other desirable trait. Release the samples to surrogate parents during the next generation.
This would also allow for the aggressive removal of genetic defects that are normally tested for during pregnancy.
My impossible experiment. Pick a point in time and isolate children from the prejudices and beliefs of their parents and society.
This is a fascinating discussion, one which I would obviously love to participate in . . . in Great Debates maybe? Or General Questions?
But in this MPSIMS thread–in which I begin by acknowledging the impossibility of the experiment–it’s a hijack.
If you’re not interested in coming up with some other impossible experiments, can you please discontinue the hijack? Again, I’d love to debate the possible outcome of this thought experiment, but that’s not what I started this thread for. Thank you for understanding.