Very much worth a read and download the animation too.
Evolution of the Y Chromosome (http://www.hhmi.org/biointeractive/evolution-y-chromosome)
Yeah, so we are just crazy mixed up guys then?
Bit bothering about future trends though, was there not something on the evolutionary death of the Y chromosone a year or four ago?
Later: perhaps not...
https://geneticliteracyproject.org/2014/08/01/y-chromosome-here-to-stay-death-of-men-has-been-greatly-exaggerated/