I guess you could technically use this to describe where babies come from to a kid but that doesn't seem to be its purpose. It spends so much time discussing other things that aren't relevant to human sexuality that either the writer was just really interested in different types of animal reproduction (I mean, it is mildly interesting that sponges, say, reproduce by budding), or was intentionally trying to obscure the information about people. I'm going to give him the benefit of the doubt and just assume he was a reproductive biologist.
Message
Different animals reproduce in different ways.
