The (female) human body is pushing the anatomic extremes to support, later bear and nurse a baby while maintaining upright posture and bipedal walk. I cannot see a way to realistically make pregnancy last any longer, which some SF writers did to explain further evolved über/super-humans or mutants – a term which I would consider slightly derogative now. I’m considering either a prolonged or a second puberty instead, but I’m not sure when these phase of physical change would occur (i.e. before or after the “fertile years”), how long it would last and what exactly could develop realistically and how it would differ for the sexes.
- pregnancy → infancy → childhood → adolescence / puberty (→ here?) → adulthood / parenthood (→ here?) → menopause / andropause → decay
For the record, I’m not thinking of mutants with individual “abilities” as depicted in X-Men or Heroes for instance, but a new generation of “growing”, more sapient human beings in general. I‘d like to get these people a larger brain (and head) with second puberty to explain increased mental powers, but other organs would probably have to grow accordingly. Any new organ seems unrealistic to me or it would have to be there (in minimal form) at birth.