Thursday, May 15, 2008

DNA is cheap and Evolution is easy

According to Discovery channel (or Nova, or one or the other of those cable versions of Popular Science), DNA analyses of the plant kingdom have turned up some surprising quirks in all the cladistics. Things like, e.g., aquatic lotus lilies turn out to be closely related to plane trees (sycamores, to us Midwesterners). There couldn't hardly be two more dissimilar lifestyles, and since standard taxonomic lineages are based on form-and-function studies, DNA cladistic analysis throws a lot of received wisdom into a cocked hat.

You could revise all the family trees to reflect current knowledge based on clades, but what is actually going on in modern botany is far more revolutionary — plant taxonomy itself is probably obsolete now, or shortly will be. The notion of "family trees" has, in and of itself, become a bit embarassing and beside the point.

That point being, DNA is cheap, and astonishingly plastic. Darwin was not only right, he was righter than anyone ever knew he could be until the 21st Century. It turns out that for all our reverence for the Big Secrets of Life recorded in those GATTACA sequences, our awe and expectations are pure self-deluded bunk. Everything alive (everything with sex, anyway) has the potential to become, in its children, an entire Australia, a whole continent of convergent designs and novel experiments, regardless of its present genetic code!

In other words, DNA is not special, and it is not fragile; it is extremely malleable and is capable of revising itself (or of being revised by accident and natural selection) nearly at the drop of a hat. That is the message of all those plant kingdom clades, which reveal closely related DNA sequences pushing into the most far-flung and outrageously disjunct niches of this planet's ecosystem. DNA is about as "special" as tile grout, and just about as costly, in evolutionary terms.

What this means is, if (say) some disaster were to wipe every living tree off the face of the Earth in the next century or two, then you might very well discover that in 20 million years, dandelions grow 80 meters tall, spread immense palm-like fronds and blow clouds of remarkably unchanged seed every Spring to the four winds.

Evolution is easy.



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