Study reveals average age at conception for men vs. women over past 250k years

If I understand the method correctly, they are actually determining the age that the sample's parents generated dna material that went on to create them.

So everyone who has a parent is included - which is everyone who ever lived.

I would hazard that they are accounted for. People had very many children, only some children survived, some of those reproduced again, I would also guess that the mothers who would die during pregnancy or during childbirth would encounter that at one of the earlier in life pregnancies, and no longer be contributing to the average. I could see all that together supporting the average age of 23.

The perennial older male age is because men are fertile longer than women so statistics would tend to this pattern over a large enough population.

There's power asymmetry, people are monsters and sexual predation is rampant but there's also biological feasibility at play here.

To demonstrate, let's say that we have an imaginary equalityville where for every age pairing and sex act, there is an exactly equal one with the ages swapped - as in mathematically perfect equality.

In equalityville occasionally 45 year old men sleep with 35 year old woman. But every time, a 45 year old woman sleeps with a 35 year old man, coincidentally, at the exact same time, doing equal things, in another part of town.

However, 45 year old woman give birth rarely. Let's say it's 1/99th the rate of the 35 year olds.

So there's

1000 45 year old women with 35 year old men resulting in 10 births

1000 45 year old men with 35 year old women resulting in 990 births

Now we're going to calculate the average age based on the babies.

Women (990 * 35 + 10 * 45)/1000 = 35.1

Men (990 * 45 + 10 * 35)/1000 = 44.9

And thus we get our paradox because we're counting by live births. So long as there are age delta pairings past some set of constraints, the male average will drift upward.

It'd be interesting to normalize for that. This is probably doable since actual fertility statistics are well studied.

I know that's a common conception about the past, but what's the actual evidence for it?

There are plenty of social and religious norms even today that keep people from getting together too young.

There's also no reason not to think people at the time understood how sex and pregnancy worked. They didn't have the internet but they were as intelligent as we are today. I'm sure they could figure out how to have "fun" without always having kids.