Professor Jobling said: "These days the X and Y are a very odd couple, but long ago, before mammals evolved, they were an ordinary pair of identical chromosomes, exchanging DNA in a companionable way through the process of genetic recombination. However, once the Y chromosome took on the job of determining maleness, they stopped talking to each other. The X remained much the same, but the Y set out on a path of degeneration that saw it lose many of its genes and shrink to about one third the size of the X. Some scientists have predicted that it will eventually vanish altogether.

"These new findings from the Department of Genetics of the University of Leicester now challenge this interpretation of the Y chromosome's fate."

The Leicester researchers discovered that the  conversation between the X and Y chromosome goes both ways, and it's also clear that mutations arising on a decaying Y chromosome can be passed to the X - the Y chromosome's revenge, perhaps! Future work will assess how widespread X-Y exchanges have been during evolution, and what the likely functional effects might be.

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