As I understand it, the point of sexual reproduction involving sperm racing each other to get to the egg is so that higher-quality sperm will outrace the lower-quality sperm, thus ensuring that the sperm that does indeed reach the egg first will be a comparatively high-quality sperm. This is the case since the sperm that is in the vagina has a long way to go before it reaches an egg high up in the uterus.
But with a test-tube fertilization - which, I’m assuming, involves putting the semen directly in contact with the egg - the “race” component is eliminated, and the egg is pretty much immediately in contact with sperm since the egg is covered with semen. By doing it this way, doesn’t this mean that inferior sperm have a much higher chance of penetrating the egg than they would through normal vaginal fertilization, since they aren’t left trailing behind superior sperm, and thus this generates a lower-quality embryo?
To use an analogy, if Usain Bolt and a dozen average humans were standing a hundred yards away from a finish line, there can be no doubt that Bolt would reach the finish line first before anyone else, but if Usain Bolt and a dozen average humans were placed six inches away from the finish line, then it’s far more likely that a non-Bolt human might get to the line first once the gun is fired.
Probably a greater concern is why IVF is needed. If a person is genetically challenged for reproduction (as opposed non-genetic problems) then you are simply passing these possible problems to the next generation…
I remember discussing this problem with a lecturer in University who was presenting the theory that genetic dilution was likely to destroy the human race within a few generations. He wasn’t even thinking about IVF, but more about non-survival traits like bad eyesight, type I diabetes, hemophilia, etc. - traits that would have killed someone before modern medicine, but are now passed down. (Think Cyril Kornbluth’s novella “The Marching Morons”) Of course, this was also before the days before many prenatal tests were available for some conditions.
The real question then, is that - barring an extreme genetic failure - is a “slow” sperm indicative that the DNA package it carries is defective, or are the majority of sperm pretty much the same? Is sperm motility a developmental issue rather than related to the quality of the genes on board?
So wait, he thought that over the 2 million years since homo erectus first appeared bad eyesight somehow managed to persevere despite its non-survival nature, but that in the 300 years since eyeglasses were invented genetic dilution is occurring? That’s quite a theory.
I posit that bad eyesight is not a problem until recently so it never had a reason to die out. If your whole life happens at the speed of a pedestrian, as it did for 99.9% of our ancestors, 20/20 vision is not really required.
The genetic link for type 1 diabetes is less clear than he supposes as well. If one twin has type 1, the other has a 30% to 50% chance of having it as well, so there’s probably an environmental link as well.
Back to the OP though, is there any evidence that the best swimmers make the best offspring? There may be no correlation at all, or even a negative one. I agree with your point about that.
One thing the OP is not considering is that the same human agency collecting sperm and using them for IVF can also observe sperm and eliminate, for example, the obviously deformed, or evaluate them for swimming vigor, and otherwise “filter” them for quality in several ways. It’s not quite the same filter as the primordial dash up the vaginia-uterus-fallopian tube route but it still allows for some sort of quality control
Yeah, see - quality control, again. We can also find out who are carriers of some conditions and those people can figure out if their chosen mates are also carriers or not, and if so, there are other steps they can do to prevent problems in their kids.
Also, a lot of things people assume are genetic really aren’t, they’re environmental. There isn’t a “diabetes gene” - Type 1 is usually an auto-immune disorder and we don’t know why those occur, or why they’re increasing in the civilized world. Bad eyesight is linked to early reading, and emphasis on reading, and that environmental factor seems to matter more than genetics. If you want to reduce myopia then make sure kids DON’T spend 8 hours a day at close-in work/reading until puberty… but that would conflict with societal pressure to put academics ahead of physical activity.
As so many things in biology, it’s a mix of influences from bad genetics/poor construction of sperm to environmental toxins to probably a bunch of other stuff I don’t know about because I’m not expert.
See this is why dating sites should incorporate DNA testing to try and eliminate double recessive pairing before the dating begins since nobody does a Genetic test on their Fiancé and makes the decision to dump her when they find out they both are carriers for sickle cell anemia.
Is there any sort of correlation between good swimmer sperm cells and good genetics? I doubt Arnold Schwarzenegger’s sperm was some buff little sperm. I would think that the formation of the sperm cell and the suitability to swim has almost nothing to do with the resulting genetic quality of a person. The genetic payload that forms a person’s genes is pretty much separate from the genetic code or simply physical production process of being a good sperm, isn’t it?
Iceland has an app called ‘bump’ that will show how closely related you are to a prospective date. This is more to avoid incest and awkwardness at grandmas birthday party, but it helps to increase gentic diversity.
I’m interested in the answer to this too. Seems to me that sperm quickness wouldn’t have much to do with the genetic code it is carrying. Also, many sperm apparently reach the egg but only one gets let in. Does the egg “know” which one it wants?