Comment by XorNot
3 days ago
Not at all: we've been doing IVF for a while now, and completely immobile sperm produce healthy normal babies.
It's the peacock's tail effect: what relevance does a brightly colored tail have to a male peacock's actual fitness?
IVF has a higher rate of spontaneous abortion which is a more expensive filter for cellular issues. In people losing out on months of reproductive heath is a meaningful downside. In say frogs having a lower percentage of viable eggs is a significant disadvantage.
IVF is also associated with congenital malformations etc. Though it’s hard to separate issues preventing normal conception from issues associated with IVF, it’s likely less viable sperm result in a less healthy fetus.
Almost completely immobile sperm can and have been used to produce healthy viable babies.
Otherwise clinically infertile men have children who are both healthy, capable and also not infertile.
Which is solid evidence that "sperm quality" is an extremely poor proxy for useful phenotypes in the resulting human being.
“can and have” sure not everything that makes sperm look feeble in a microscope actually represents an issue.
Extremely poor is a qualifier that isn’t backed up by your previous statements or actual scientific studies. Further births are very late in the process, rates of success is a critical metric here.
There’s significant research in trying to artificially create similar selection criteria because it increases the odds of a successful pregnancy and live birth. https://pmc.ncbi.nlm.nih.gov/articles/PMC7365522/
So if you still disagree, how about presenting some actual evidence.
The tail’s appearance is a meaningful proxy for the state of health of its holder.