All true.
But of the billion sperm in any one shot, the best swimmers and egg wall poker-throughers will have better odds over their slower & weaker brethren. They are not all clones of one another.
Yes, but it’s not a race between Bob and Ted and Bill - it’s just Bob, the healthiest of his sperm in terms of motility will survive. Bob will reproduce. In fact, our tendency (somewhat) to monogamy and long term relationships, and to limiting the number of children we produce (usually) means that most men do not have a reproductive advantage the way Genghis Khan did, or the Saudi rulers. Even there, the advantage (reproductive differential) over other males is not generally determined by sperm strength.
Well, if Bob has “better” sperm in the sense of a great pregnancy : intercourse ratio, then yeah, he is competing with Ted and Bill, all other things being equal (the greatest, of course, are those of their wives in having successful pregnancies and births).
Every time I see this thread, my head cues up this earworm…
Or the famous Monty Python song:
Depends. The ones with 100 wives didn’t get so many wives by the strength of their sperm. In a typical monogamous world, where at a certain point “enough is enough” most couples stopped with the number of children they were content with. Sperm strength would be of marginal benefit, as normal sperm would get the job done within a few months to a year anytime. Higher birth rates were associated with the lower class (who didn’t care as much?) and the rich (who could afford nannies). Neither of those attributes was earned by strong sperm, unless we consider that a man became poor because his father had too many children.
So the only exception might be the Don Juan types, who impregnate a plethora of impressionable susceptible women. Again, they don’t get the high count by the strength of their sperm, and it’s a crapshoot (so to speak) whether they mate at the right time with the female, so it may not matter. (And we’re back to “with a billion sperm at a time, how strong does each one really need to be?”)
Well, OK-- but remember that lots of pregnancies were lost, and lots of babies didn’t make it through the second year-- with the first 3 months being so dicey, that in Judaism, you didn’t formally mourn a baby that died at less than 3 months.
So, you might have to be able to knock up your wife almost as soon as she was able to carry another pregnancy, just in order to have a family or six or seven. A man who aided in conception less frequently-- say, 10 times in the context of a women’s fertility, working around pregnancies, from age 17 to about 42, might have 6 adult children if he was lucky.
Someone who could aid in conception with greater frequency could end up with a lot more children who make it to adulthood.
As far as “enough is enough,” that didn’t come into play until reliable birth control.
Which actually brings up another point-- in the days when toddlers were routinely nursed until past the age of two, and nursing suppressed, but did not stop, ovulation, maybe men with sperm that lasted longer ex corpore, were better-able to impregnant nursing mothers.
If someone’s sperm had an ex corpore lifespan around 36 hours, you had to have intercourse almost every day, but if the lifespan was 5 days, then twice a week was more than enough. Even allowed for some time off for some hunt, or plowing or scrimmage or something.
Motility matters too, in such cases, and so does volume, albeit, I wouldn’t consider “volume” an aspect of strength. Motility and longevity, definitely, though.
Having a whole lot of kids in poor conditions is likely to reduce the chances of each one’s surviving to adulthood.
There’s a possible nasty negative loop in which people have many children because they don’t expect them all to grow up, but because they have so many children a lot of the kids die of malnutrition combined with diseases of crowding.
That presumes control over fertility & conception people have not historically had.
But you’re presuming that getting pregnant again rapidly results in raising more children to adulthood. If there’s a high death rate in early youth a man whose wife gets pregnant less often may raise as many children as the man whose wife gets pregnant more often. Also, the wife’s likely to herself survive longer; if he’s in a position to get married again almost immediately, or if the society’s not monogamous, that might not appear to matter as much – but the children of mothers who die while the children are young are probably less likely to live to grow up.