Oryx and Crake by Margaret Atwood

Pigs might not fly but they are strangely altered. So, for that matter, are wolves and racoons. A man, once named Jimmy, lives in a tree, wrapped in old bedsheets, now calls himself Snowman.

The voice of Oryx, the woman he loved, teasingly haunts him. And the green-eyed Children of Crake are, for some reason, his responsibility.