This is mainstream biology. A text book here describes this. www.google.co.uk/books/editio...
This is mainstream biology. A text book here describes this. www.google.co.uk/books/editio...
The biology literature is full of papers that discuss why we have two sexes and their nature. pmc.ncbi.nlm.nih.gov/articles/PMC...
And where in those texts do we find the claim that a third sex cannot evolve? And where are my stats or are you just arguing in bad faith now?