Interlocus Contest Evolution, ICE, is the process by which an X chromosome, in a male, doing what it normally does, collecting genes it thinks are useful, steals a gene from the Y chromosome.
The default sex of humans is female with 2 X chromosomes (1 from ma, 1 from pa). Normal operation means one X becomes dominant and deactivates the other. In males there is an X and a Y. Since the Y chromosome must play "hide and seek" with the X so it does not get de-activated, when the X steals one of its genes the Y has to choose another gene, or shrink in size. This is why the Y is so small in humans and it is why the Y in all human males is virtually the same, believe it or not.
Ancient women were more feminine and ancient men were more masculine. Over time the sexes have moved closer together.
Interlocus Contest Evolution may sound like something cool but its not, for the Y. Over time the Y shrinks and the question is what happens in the end? Could it be that the Y disappears entirely? If it does then what happens to the species?
In far eastern culture a man who moves from woman to woman, refusing to be tied down, is known as a “butterfly”. Quite correct this analogy. In the butterfly species there are very, very few males. In the case of the Acrea Encedon species, it was caused by the X choosing a gene that was deadly to the Y. This could happen in the Human race too, by accident or by purpose. This could explain why HGP is not so forthcoming with DNA discoveries.
We are but machines, gene machines, sex machines.