I'll recount from a 10+ years gap of memory - and also with a disclaimer that this is not my area of expertise, by far. So, please don't believe me without add

I'll recount from a 10+ years gap of memory - and also with a disclaimer that this is not my area of expertise, by far. So, please don't believe me without additional supporting evidence. However, what I took away from those classes was that gender was a very mutable 'invention' that Humans created through culture to systematically specialize labor in response to environmental forces. Some cultures invented two-genders, aligned with biology, to succeeded in environments where two specialized gender roles were more advantageous. However, other cultures of Humans invented several types of genders, and genders that crossed biology, to succeeded in different environments. So, if those memories are even accurate, gender and gender roles in Humans are more aligned with the overarching systematic cultural forces than biology. And, even if we consider biology, there is a lot of cross-over. Humans are a very adaptive and mutable species.