Monday, March 29, 2010

On The Wings of Evolution

Dan Vergano of ooh-es-ahh-heute (USAToday) has a story on how wings may have evolved in insects. They plainly have creationists in the cross-hairs:
Wings allowed bugs to become the most widespread critters on Earth, about three-quarters of all animals, but the fossil record offers no clues to their origin. Wings probably already graced the oldest known insect fossil, Rhyniognatha hirsti, about 400 million years ago.

Some religious writers — such as Matthew Vanhorn of Apologetics Press in Montgomery, Ala., who wrote that the "evolution of insect wings and subsequent flight is a concept impossible for evolutionists to explain" in a 2004 essay on the topic — have seen holes in evolutionary biology in the lack of an insect wing explanation.

But it turns out that just two genes may explain insect wings, reports a team led by Japan's Nao Niwa of the RIKEN Center for Developmental Biology in Kobe.
According to the story, the authors used mayflies and wingless bristletail insects, which are considered to be more primitive in their genetic makeup when compared to animals like butterflies. Here is what they found:
A gene called "vestigial" and another called "wingless" (so named because it prevents wing growth when mutated in fruit flies) work together during the insects' embryonic growth to sprout wings in mayflies, and fail to fire up in the silverfish.

Both genes already were present in the wingless ancient ancestor of today's flying bugs, the researchers note, because they had other jobs to do. One plays a role in development of body shell sheets (vestigial) and the other helps limb growth (wingless). Add them together and you have a shelled limb — a wing, they conclude.
This is still a bit sketchy but it is a workable, testable model for examining this aspect of evolution.

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