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Comment by anticensor | Hacker News Reader

Humans are double-viviparous species, meaning average grandparent lives past its grandchild's puberty. Humans are also atricial. These traits are shared by elephants, whales and dolphins too. However, humans are the only animal species those are triple-viviparous in occasions, meaning great-grandparent lives past its great-grandchild's puberty.

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Human's average lifespans have been a lot shorter throughout history.

Average isn't that relevant. It's driven down by early childhood deaths & childbirth deaths (but after a point - menopause - childbirth deaths end).

Infectious disease killed many before old age. Antibiotics are a pretty recent invention.

Yeah, but the impact isn't that great.

According to Our World In Data [1] a 20-year-old would expect to live to 60 in 1850 (before penicillin), versus to 80 now.

[1] https://ourworldindata.org/life-expectancy#it-is-not-only-ab...

That's still long enough for a person to see their grandchildren reach and cross puberty.

Especially in a world where kids were born when the parent was in late teens or early 20s, rather than now when average age is 28 and pushing higher.

This means first grandchildren in early 40s (rather than late 50s), and first great grandchildren by mid 60s (rather than mid 80s)

And infectious disease was probably a much smaller problem for hunter gatherers living in small groups, which has been the case for the vast majority of our evolutionary history.

Historical average is relevant. I have an 18 year old cat. It's an aberration. We evolved under specific pressures. Only recently, have we removed specific age gates.

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