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Comment by Hendrikto | Hacker News Reader

> we (at least women) are only fertile for around 1/4 of our total life

What? Women become infertile around 45-50. Going with the lower bound, your 1/4 figure implies a lifespan of 180 years.

Much higher probability of birth defects and fertility problems at that point, even if you're still menstruating.

For people wondering exactly how "much higher probability". This is for example down syndrome, but many of the other syndroms follow the same trend:

https://courses.fetalmedicine.com/images/Course/Course.007-0...

Notice the y-axis is a log scale.

This may be offset if women froze their eggs beforehand, but, obviously not everyone can afford it, and also until recently, it wasn't really needed as couples would have children earlier in life.

Man that's insane! I have always wanted kids but never got married. I am a man in my late 20s so finding someone my own age is starting to scare me a little

It does not get that bad pre 35 so you do have some runway. Do not waste it all on that praised kidult stuff, though.

That's nonsense. Onwards from 35 it becomes exponentially harder for a woman to become pregnant, let alone the complications the child may have.

Women only become fertile at age 15, and socially acceptably fertile at 20. 45-50 is a very optimistic upper bound, even with that bound you end up with ~1/3 figure.

> Women only become fertile at age 15

More like 12-13, but you are right. I did not consider that.

menarche tends to average around 12 (with a wide range), but most cycles don’t involve actual ovulation for the first few years after menarche, so fertility and menarche aren’t simultaneous.

It's interesting to me that the average age at menarche has been declining in recent years - and that we don't really know what that's the case.

For example: https://www.cdc.gov/nchs/data/nhsr/nhsr146-508.pdf

Now I'm wondering if there has been any change in the age of the onset of menopause, and whether that's been studied...

These who are able to have healthy offspring late in their lives are at tremendous evolutionary advantage now, whereas historically it was a selectionary 'meh'.

I wonder if that leads society to unwittingly be selecting for longer lifespan, if maximum lifespan and maximum reproductive age are correlated.

Lifespan is almost worthless if you are not in tolerable mental and physical condition, and prolonged fertility likely correlates with both. You need to be fit to be fertile.

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