Sunday, July 12, 2009

Selfish DNA: Dawkins

The origins of the selfish DNA hypothesis, later elaborated by Orgel and Crick and Doolittle and Sapienza (1980; both to be covered in a future post), reside in one of the more popular books written by Richard Dawkins The Selfish Gene. For those who haven't read it the book is essentially Dawkins' treatise on how he feels the sole units of evolution are genes and most of everything else is just an extrapolation from this level. Although I disagree with Dawkins' assertion that genes are the fundamental units and targets of selection I do recognize that he was the first to propose that the copious amounts of seemingly superfluous DNA found within metazoan genomes could be explained using his selfish gene theory.
In his own words, from the 30th anniversary edition of the book, pages 44-45:

"Sex is not the only apparent paradox that becomes less puzzling the moment we learn to think in selfish gene terms. For instance, it appears that the amount of DNA in organisms is more than is strictly necessary for building them: a large fraction of the DNA is never translated into protein. From the point of view of the individual this seems paradoxical. If the 'purpose' of DNA is to supervise the building of bodies it is surprising to find a large quantity of DNA which does no such thing. Biologists are racking their brains trying to think what useful task this apparently surplus DNA is doing. From the point of view of the selfish genes themselves, there is no paradox. The true 'purpose' of DNA is to survive, no more and no less. The simplest way to explain the surplus DNA is to suppose that it is a parasite, or at best a harmless but useless passenger, hitching a ride in the survival machines created by the other DNA."

Only a few sentences but they would be the beginning of what was to come next in 1980. More on that in the next post.

P.S. Sorry that this is so short, stay tuned.

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