New Scientist leaves us in no doubt: the platypus is not like other animals.
Wesley Warren at Washington University in St Louis, Missouri, led the international team that sequenced the platypus genome. As expected, they found an amalgam of some ancestral reptile and some newer mammalian features. But there were also surprises.
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And while the gene that the human sex-determining gene evolved from is present in the platypus genome, it seems to have nothing to do with sex determination. So, that function must have evolved after the platypus split from our common ancestor, about 166 million years ago.
However, by that time, milk production was well-evolved. The platypus has the same repertoire of milk protein genes as a cow or a human. Clearly, milk evolved long before we evolved to give birth to live offspring, says team member Jenny Graves at the Australian National University in Canberra.