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 today (July 19) 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.
“This paper is definitely an exciting contribution to the understanding of the early days of sex chromosome evolution,” said evolutionary biologist Manyuan Long of the University of Chicago, who was not involved in the research. “Now we know that, in nature, sex chromosomes can evolve very rapidly.”
The human X and Y chromosomes are thought to have originated from a matching pair of non-sex chromosomes, or autosomes, some 200 million years ago. ...
