Thursday, June 28, 2007 | Science : Evolution and Biology | print version

From a Few Genes, Life's Myriad Shapes

by Carol Kaesuk Yoon, NYTimes.com

Thanks to ranjani for the link.

Reposted from:
http://www.nytimes.com/2007/06/26/science/26devo.html?_r=1&ref=science&pagewanted=all&oref=slogin

helix

Since its humble beginnings as a single cell, life has evolved into a spectacular array of shapes and sizes, from tiny fleas to towering Tyrannosaurus rex, from slow-soaring vultures to fast-swimming swordfish, and from modest ferns to alluring orchids. But just how such diversity of form could arise out of evolution's mess of random genetic mutations — how a functional wing could sprout where none had grown before, or how flowers could blossom in what had been a flowerless world — has remained one of the most fascinating and intractable questions in evolutionary biology.

Now finally, after more than a century of puzzling, scientists are finding answers coming fast and furious and from a surprising quarter, the field known as evo-devo. Just coming into its own as a science, evo-devo is the combined study of evolution and development, the process by which a nubbin of a fertilized egg transforms into a full-fledged adult. And what these scientists are finding is that development, a process that has for more than half a century been largely ignored in the study of evolution, appears to have been one of the major forces shaping the history of life on earth.

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1. Comment #52969 by J Steven on June 28, 2007 at 8:03 pm

It bears repeating:

"I'd take the awe of understanding of the awe of ignorance any day."

Thank you Mr. Adams!

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2. Comment #53013 by CJ on June 29, 2007 at 2:23 am

If I have understood this correctly it would appear that so called "toolkit genes" control the development of overall structures in animals e.g. beak length. So beak length changes with a mutation in its controlling toolkit gene. So the mutation is simple at the DNA level but produces a disproportionate effect in beak length. In part of the toolkit gene is encoded beak length = 7mm, a small mutation in this area of the gene would change beak length to any value in the range 0mm to 1km. So this simple and therefore possible mutation can produce significant structural change and then natural selection then comes into play and the bird with the 11mm beak gets to exploit a different food source in the environment better than the 7mm version and speciation starts to occur.

It would appear that there is a balance in gene stability and desirable mutation. The highly stable gene pattern that throws out few mutations eventually gets caught out by environmental changes and becomes extinct. A gene pool with too high a rate of mutation would eventually mutate itself out of existence because it could not breed true. Somewhere between these extremes would be a band of optimal mutation rates where natural selection would operate to produce speciation.
So natural selection would actually militate against complete genetic stability and total genetic chaos, which appears to be exactly what we see around us.

Fascinating stuff!

Of course this is where the faith-heads start chanting "Science got it wrong again, look they've changed their minds!", yet again deliberately missing the point of the scientific method.

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