Australian platypus genome a link to evolution

By Michael Perry

SYDNEY (Reuters) - Australia's unique duck-billed platypus -- an egg-laying, furry animal with web feet that spends most of its time underwater -- is in fact part bird, part reptile and part mammal according to its gene map.

A team of international scientists released the platypus genome on Thursday, saying its complex sequence would aid the study of human evolution -- particularly the development of the immune, nervous and reproductive systems.

"Its probably the most eagerly awaited genome since the chimp genome because platypuses are so weird," said Jenny Graves, head the Comparative Genomics Group at the Australian National University.

"Comparing us with the platypus means that we can say something about our common ancestor, which was one of the earliest mammals, so that means that we can ask questions about what happened to make us mammals," said Graves, after a briefing on the platypus genome, published in the journal Nature.

The platypus represents the earliest offshoot of the mammalian lineage, some 166 million years ago, from primitive ancestors that had features of both mammals and reptiles.

When the platypus was first discovered, English scientists regarded it to be an Australian joke, thinking someone had stuck a duck's bill and feet onto an otter-like animal.

The platypus is classified as a mammal because it produces milk, suckles its young and is covered in fur, but it also lays eggs like a bird or reptile and males have poisonous spurs on their hind legs like a reptile.

CLUES TO HUMAN EVOLUTION  Continued...