Reproduction and Parenting -- summary

Primates are mammals

All share a very similar reproductive process, with similar hormones and outcomes.  For example, regions of the Y chromosome cause the  fetal gonad to secrete male hormones (androgens), which in turn modify the fetus – including its brain and genitals – to be a male.  Without those hormones, the body would develop the appearance of a female.

Humans and apes have much in common

Usually single births

8-9 months gestation etc.

great maternal investment

This includes bearing the fetus, birth, and a long period of nursing and care preparing her offspring for independent life as adults.

Mothers' competence in non-human primates is related to their own hands-on experience in their youth.  This may be true for humans as well.

Early maternal contact ('attachment')  has important consequences for adult cognitive and social/sexual competence.

Long juvenile period and long life expectancy

Human-ape differences

Erotic images – what's attractive in mates – vary by species and to some extent, culture.

Ovulation in human females is concealed

Compare with chimps where pink swellings advertise ovulation directly.

Even slower development – at birth and to maturity

Human gestation would be 21 months if our brains were born at the same level of maturity as the average primate. 

While human cervical opening is not much different from large apes, the immature human skull remains flexible enough to squeeze through just in time.

Although diet plays an important role, human auditory cortex may not be fully mature until late teens.

Greater paternal investment

Females require assistance at birth

Ape mothers give birth on their own and infants are mature enough to support themselves on motherŐs hair within weeks.

Relative prematurity at birth exposes brain to culture as brain is still developing

At the same time, this prematurity makes both mother and neonate dependent on social support much more than other hominoids.

Human social structure enables earlier weaning and  consequently more offspring since nursing lessens maternal fertility.

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