TWO centuries after a dead specimen was deemed so outlandish it had to be a fake, the bizarre genetic make-up of the platypus has been laid bare.
Wesley Warren at Washington University in St Louis, Missouri, led the team that sequenced the platypus genome. As expected, they found an amalgam of reptile and mammalian features, but some surprises, too.
It turns out the gene sequences responsible for determining sex are more like a bird's than a mammal's. Though the gene that evolved into the human sex-determining gene is present, that is not its job. So the function in humans must have evolved after the platypus split from our common ancestor, about 166 million years ago. Yet the platypus has the same repertoire of milk protein genes as a cow or a human, so clearly milk evolved long before the ability to have live offspring (Nature, DOI: 10.1038/nature06936).