The journal Nature publishes an article on sex and gender.
Coyne takes them to task for conflating the two:
And I find a really good article that asks of gender is unique to humans:
This summer, in the introductory course I teach on the evolution and biology of human and animal behavior, I showed my students a website that demonstrates how to identify frog “genders.” I explained that this was a misuse of the term “gender”; what the author meant was how to identify frog sexes. Gender, I told the students, goes far beyond mere sex differences in appearance or behavior. It refers to something complex and abstract that may well be unique to Homo sapiens . This idea is nothing new; scholars have been saying for decades that only humans have gender. But later that day I began to wonder: Is it really true that gender identity is totally absent among nonhuman species—even our closest evolutionary relatives, chimpanzees and bonobos?
Before tackling this question, it is necessary to define “sex” and “gender.” Sex refers to biological traits associated with male and female bodies. Sex isn’t a perfect binary, but it is relatively simple compared to gender.
Gender is multifaceted, complex, and a little abstract, and not everyone agrees on exactly what it means. That said, there are a couple of aspects of gender that most experts say are essential. The first is the existence of socially determined roles. Gender roles refer to the range of behaviors that society deems normal or appropriate for people of a particular gender based on their designated sex—the norms that (at least in many Western cultures) cause us to expect men to be assertive and brave, and women to be caring and accommodating, for instance.
Have you looked into this at all @NLENTS?