Scientists Map Platypus Genome

Comedian Robin Williams once suggested that the platypus was proof that God smoked pot on occasion, “OK, first, take a beaver, let’s put on a duck’s bill . . . .OK, he’s a mammal but he lays eggs.” Scientists have just finished mapping the platypus genome, and they found that the beast is just as distinct genetically as it is physically. The results are reported in yesterday’s edition of Nature.

The reason the platypus is such a valuable genome to have mapped is its inherent weirdness. There is only one other mammal, the echidna (also known as the spiny anteater), that lays eggs. Platypus females lack breasts as such and provide milk to the young as it oozes from the skin on the abdomen. Underwater, it closes its eyes, ears and nostrils, using its duckbill as an antenna that can sense the weak electric forces around other animals. The males have a venomous spur at the back of their legs, making them the only poisonous mammal.

Rick Wilson, director of The Genome Center at Washington University in St Louis and part of the study, told Reuters, “You see genes that look reptile-like, genes that look bird-like and genes that look mammal-like. It’s a pretty amazing picture.” Yet it shares more than 80% of its genes with other mammals, from whom the species branched off about 166 million years ago. Chris Ponting of Oxford University told the Agence France-Presse, “This is our ticket back in time to when all mammals laid eggs while suckling their young on milk.”

One of the interesting things the study discovered was the existence of X and Y chromosomes, just like in humans -- well, not just like in humans. In the platypus, the X and Y chromosomes aren’t sex chromosomes. Jenny Graves, head of the Comparative Genomics Group at the Australian National University, said, “That means we can go right back to the time when our sex chromosomes were just ordinary chromosomes minding their own business and ask well what happened, what made them into sex chromosomes.” The study showed that the platypus has 52 chromosomes, and of these, 10 are sex chromosomes – five for male and five for female. This is, apparently, standard for birds. Humans have but one of each.

While the platypus may have been God’s experiment in Dadaism, this study will offer insights into evolution that would otherwise not arise. As with most things, the bizarre and extreme example offers a mirror to the normal and mundane.

© Copyright 2008 by The Kensington Review, Jeff Myhre, PhD, Editor. No part of this publication may be reproduced without written consent. Produced using Fedora Linux.

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