In my world there is a certain sapient species with height around 3 meters, whose bones are more durable than humans, meaning they can afford wider pelvis than most human women

I personally believe around one year should be sufficient

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    $\begingroup$ "Underdeveloped" in this context is by comparison to ungulates, which can stand and walk minutes after birth, or to many lizards and snakes that are completely independent when born/hatched. Compare to kittens, that can't see or hear for ten days, and humans are well developed, and compare to marsupial pups and we're practically adults at birth. $\endgroup$
    – Zeiss Ikon
    Sep 9, 2022 at 13:16
  • $\begingroup$ Underdeveloped by what measure .. How developed do you imagine 'fully developed' is, do you want full size walking talking humans at birth or what? .. Why do you think women can't have wider pelvises with existing bone density? .. Do you really think pelvic size is the only limiting factor for human birth weight? $\endgroup$
    – Pelinore
    Sep 9, 2022 at 13:30
  • $\begingroup$ Those first two comments get at the issue. What meaning are you considering humans underdeveloped. We are not fully developed until after puberty. So what point of fully developed are you trying to get to? $\endgroup$ Sep 9, 2022 at 14:40
  • $\begingroup$ Also consider which factors must necessarily develop after birth. For instance, even rudimentary language skills. So the development goal might end up with some odd consequences - for example, imagine a baby popping out with the ability to run around like a toddler but with no familiarity with the world nor ability to understand even the word "no!". $\endgroup$ Sep 9, 2022 at 14:49
  • $\begingroup$ since intelligent brain development requires experience in the real world the answer is never, there is a reason all primate babies are "underdeveloped" compared to ungulates. $\endgroup$
    – John
    Sep 9, 2022 at 20:28

1 Answer 1


they can afford wider pelvis than most human women

Human babies are born underdeveloped because their metabolic needs at that time can be barely satisfied by the mother's body: any higher energy request would simply kill the mother of exhaustion.

As a consequence, it's not a problem of having larger or more resistant pelvic bones. You creatures would not have longer pregnancies: if their babies have the same energetic balance with respect to their mothers as humans do, they would also be born underdeveloped.

  • $\begingroup$ And now I'm trying to imagine just how big women's hips might be and what other changes to female physiology and form might be expected if the nutritional needs of much larger babies were sustainable. $\endgroup$
    – Pelinore
    Sep 9, 2022 at 13:20
  • $\begingroup$ Do you have any sources for this claim? As I understand it, it's fairly common for mothers to supply the majority of a baby's energy for perhaps half a year after the child is born $\endgroup$
    – Nolimon
    Sep 9, 2022 at 22:36

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