Sex Drives Chromosome Evolution

Sex Drives Chromosome Evolution

Given the dramatic difference in the size and sequence of the human X and Y chromosomes, it’s hard to imagine that they were once a perfect matching pair. But in fact all sex chromosomes start out that way. New research published in Science examines the early phase of sex chromosome evolution in a strain of fruit flies that recently—1 million years ago—converted a normal pair of chromosomes into a new mismatched X and Y duo.