Thursday, May 8, 2008

The platypus: new evolutionary insight?

A team of scientists has determined the platypus's entire genetic code. And right down to its DNA, it turns out, the animal continues to strain credulity, bearing genetic modules that are in turn mammalian, reptilian and avian. There are genes for egg laying -- evidence of its reptilian roots. Genes for making milk, which the platypus does in mammalian style despite not having nipples. Genes for making snake venom, which the animal stores in its legs. And there are five times as many sex-determining chromosomes as scientists know what to do with.Yet in its wackiness, Wilson said, the platypus genome offers an unprecedented glimpse of how evolution made its first stabs at producing mammals.