Wednesday, June 13, 2007

Non-coding DNA, Junk and Creationism

Larry over at Sandwalk straightens out a very confused writer at Wired. (Also check out the links in Larry's post to other responses). Larry does a great job going over the article in detail, but I can't resist commenting on a piece that is so badly off track.

Catherine Shaffer, who claims to be very knowledgeable about genomics has written an extremely confused article about the non-debate over whether recent discoveries about 'junk DNA' support creationism.

I can't believe anyone knowledgeable about genomics would write this (referring to the recently published opossum genome sequence):

"The opossum data revealed that more than 95 percent of the evolutionary genetic changes in humans since the split with a common human-possum ancestor occurred in the "junk" regions of the genome. Creationists say it's also evidence that God created all life, because God does not create junk. Nothing in creation, they say, was left to chance."

The fact that most changes occur in 'junk' regions supports creationism??? We expect most differences between the opossum and human genomes to occur in non-functional (that is, junk!) regions because that's where random mutations don't get swept away by selection. Most functional regions will have undergone much, much less change than the wide swaths of non-functional DNA that can get hit by random mutations without any effect on the survival of the organism.

People who study gene regulation (myself included) look for the functional stretches of DNA by doing exactly the opposite of what Shaffer is suggesting - we look for regions that don't change much among distantly related species. Those places are where you find the regulatory elements. And those elements really are surrounded by junk - our genomes are filled with the remains of mostly inactive genetic parasites and other low-complexity repeated sequences. We have fairly good ideas of how such junk sequences are produced, and many of these ideas have been tested in the lab.

Beyond making it abundantly clear that Shaffer knows essentially nothing at all about genomics, the article shows that Creationists like Behe and Meyer, who are gleefully quoted, know nothing about genomics either.

1 comment:

Plabius Quintas said...

I am not a microbiologist, but am a mere janitor in an office building... who watched the film "Good Will Hunting".

However, I do have a coupla graduate degrees (incidental/accidental)...

Here's my scoop of stuff...

Most of the human genome coding is set to accomodate the salient (successful)'human' features and functions (in balance) to (with) the environment. Assuming the driver for evolution is adaptation (everything is an assumption), then the environment must leave an imprint in human genetics insofar as the 'shape' of humanity is simply a biological reaction to environmental conditions. It seems obvious to me that a mechanism must exist to regulate this very important issue. Within the human genome is a kind of 'map'(white noise) of all the environments by which we have been created. The core specific to humanity is an abreaction process out of which is produced blue-eyed blonds :). Human intelligence is perhaps an interesting variation in the pattern of human specificity, but maybe it is insignificant to the big picture of speciation on the spaceball called earth.
(Logon Didonai)