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Science Frontiers ONLINE No. 75: May-Jun 1991 |
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Can organisms direct their evolution?
"In 1988. Harvard molecular biologist John Cairns committed an act of scientific heresy. He proposed in a Nature article that bacteria living in an unfavorable environment are able to choose which mutations to produce to adapt to the stressful situation. Cairns made his directed-mutation hypothesis in response to an unusual finding -- data that strongly hinted bacterial mutations might occur more often when beneficial."
The above quotation is the lead paragraph in a long BioScience article that details the consternation Cairns' results have created in the biological community.
The problem that biology-as-a-discipline has is that it has deified a paradigm: neo-Darwinism. Now, neo-Darwinism is supported by many experiments showing that some mutations are indeed random. Consequently, as M. Gillis re-marks in her BioScience article, the biological community 'got locked into its belief that an organism cannot control its own mutation.' Furthermore, Cairns' claims recall the long battle with Lamarckism, a subject that biology has closed-the-book-on. In a nutshell, Lamarckism has been interred since the 1950s, and 'Nobody wants to give the appearance of straying from the neoDarwinism fold.'
Gillis goes on to review some recent experiments supporting those of Cairns. But, impressive though these may be, there have been neo-Darwinian explanations for some of the results. Even so, more and more biologists are now willing to accept at least the possibility of non random mutation of bacteria.
But, in the end, all participants in the debate recognize a great void: There exists no acceptable mechanism by which a life form can steer its own evolutionary way; that is, shape its own genome. What besides natural selection can do this?
(Gillis, Anna Maria; "Can Organisms Direct Their Own Evolution?" BioScience, 41:202, 1991.)