Rediscovering Life

What Absent Genes Don’t Do — And How Can We Know?

Stephen L. Talbott

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Posted: June 15, 2013   (Article 4)

The June 7, 2013 issue of Science has a special section on the “Mysteries of Development”. One of the pieces cites Cambridge University (UK) developmental biologist, Peter Lawrence, on the idea that “far too much of what we know about development involves what happens when things go awry”:

“If a mutant gene causes an organism’s head to fall off, the conclusion is that the gene’s function is to hold the head on,” he says. “People have applied this logic, inappropriately to complex phenomena like the building of an organism.” The focus on mutations, he says, has distracted the field from some of the most important questions in development, which require understanding what genes do when they are working as they should.

Despite the fact that nearly the whole of genetic science has for many decades been built upon the search for differences when a gene is disabled or otherwise mutated, neither the public nor even many biologists have been aware of the severe distortions of this approach. Surely we learn something when we “knock out” a gene (as the usual terminology has it). But we don’t learn very much — not until we are able to turn all the negatives (what is missing or “incorrect” when a gene is disabled) into something positive. This requires a different sort of looking.

Defining what goes wrong when we mutate a gene isn’t even possible until we have some picture of the “right” that has been “wronged”. And the only way to get such a picture is to gain an understanding of the overall, harmonious functioning of cell, tissue, organ, and organism. This is a synthetic task, requiring a grasp of unities and intentions rather than of symptoms attributable to the missing “functions” of isolated genes that never do function in isolation.

Actually, disabled genes often do not even present us with missing functions, since the deletion of a gene simply leads the organism to compensate for its absence in some other way. Biologists have been startled to learn that a great many genes, when deleted, do not result in obvious defects. And yet (this is often overlooked), those genes surely do play significant roles in the organism. It’s just that organisms are highly plastic and adaptable beings, able to pursue their own intended path via many detours and adjustments to circumstances.

What is positively needed, in other words, is (dare one say it?) a “holism” — a piecing together — that amounts to a kind of portraiture rather than merely analysis — something biologists seem to be reaching out for today, however inadequately, when they speak of “systems biology” and the importance of context.

Tags: gene/mutation; gene/as difference-maker; holism
Source: Vogel, Gretchen (2013). “Under Development”, Science vol. 340 (June 7), pp. 1161. doi:10.1126/science.340.6137.1161
Further information: See the section “From differences to character” in my article, “Missing Heritability — Or Whole-Organism Inheritance?”: http://natureinstitute.org/txt/st/mqual/genome_10_inherit.htm#gene_diffs. Also: “Biological Truth as Character Portrayal Rather Than Causal Explanation” (forthcoming): http://natureinstitute.org/txt/st/org/index.htm/#portrayal.

This document: BiologyWorthyofLife.org/comm/ar/2013/absent-genes_4.htm

Steve Talbott :: What Absent Genes Don’t Do — And How Can We Know?