Why the Y chromosome is a hotbed for evolution Mark Henderson, Science Editor The Y chromosome is often seen as the rotten corner of the human genome — a place of evolutionary decline that is slowly decaying and threatening the end of man. Reports of its imminent demise, however, have been exaggerated. Research has indicated that, far from stagnating, the male chromosome is a hotspot of evolution that is changing more quickly than any other part of humanity’s genetic code. In most mammals the sex of offspring is determined by X and Y chromosomes. Females have two Xs, males have...