Question

how did our ancestors know about the process of reproduction

Answer 1

They didn’t. There is no obvious relationship between sex and pregnancy.

Having sex is instinctual, it is an inbuilt capacity for having pleasure that also creates emotional bonds between people.

Relating that to childbirth, that can happen or not nine months later, is a cultural achievement and has to be learned socially.

The role of the male in the phenomenon of pregnancy took a long time to understand. We still use expressions like “she gave him a child”, indicating an ancient belief that pregnancy is something women do on their own. There are still cultures where people believe that a couple should have extra much sex during pregnancy because a well-formed child depends on a regular supply of semen to the womb during pregnancy.

Knowing how to “have the baby”, as in how to deal with labour, childbirth and childcare, is partly instinctual and partly learned from experienced mothers.