This is a great (and short) explanation of why biologists usually roll our eyes when we hear nonsense like "there are exactly 2 human sexes" or "all humans are either male or female", or especially "it's easy to tell if someone's male or female - just measure [some trait]". People are complicated and biology is messy. Evolution doesn't care about our biases or preferences; it just muddles along with whatever works well enough.
https://theconversation.com/biological-sex-is-neither-binary-nor-a-spectrum-a-biologist-explains-how-its-multidimensional-289786
#biology #SexDetermination
