5 ms·

> 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

> 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.

nerdponx 3y ago
Much higher probability of birth defects and fertility problems at that point, even if you're still menstruating.
- kpw94 3y ago
  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.007-000.png 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.
  - danjoredd 3y ago
    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
    - thriftwy 3y ago
      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.
htatche 3y ago
That's nonsense. Onwards from 35 it becomes exponentially harder for a woman to become pregnant, let alone the complications the child may have.
thriftwy 3y ago
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.
- Hendrikto 3y ago
  > Women only become fertile at age 15 More like 12-13, but you are right. I did not consider that.
  - dragonwriter 3y ago
    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.
    - Ancapistani 3y ago
      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 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...
      - thriftwy 3y ago
        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'.
        Qem 3y ago
        I wonder if that leads society to unwittingly be selecting for longer lifespan, if maximum lifespan and maximum reproductive age are correlated.

> 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.

nerdponx 3y ago

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

kpw94 3y ago
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.007-000.png 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.
- danjoredd 3y ago
  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
  - thriftwy 3y ago
    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.

htatche 3y ago

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

thriftwy 3y ago

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.

Hendrikto 3y ago
> Women only become fertile at age 15 More like 12-13, but you are right. I did not consider that.
- dragonwriter 3y ago
  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.
  - Ancapistani 3y ago
    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 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...
    - thriftwy 3y ago
      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'.
      - Qem 3y ago
        I wonder if that leads society to unwittingly be selecting for longer lifespan, if maximum lifespan and maximum reproductive age are correlated.