Thursday, August 9, 2012

Evolutionary biology applied to medicine and agriculture

[ This post is by R. Ford Denison of the University of Minnesota; I’m just posting it. –B. ]

Evolution happens.  Careless use of antibiotics selects for antibiotic-resistant pathogens, careless use of insecticides (including crops that make their own insecticides) selects for pesticide-resistant insect pests, and careless use of herbicides selects for herbicide-resistant weeds.

Many people seem to assume that this well-known problem, evolution of resistance, is the core of “Darwinian medicine” or “Darwinian agriculture.” But check the tables of contents of the books above. You’ll only find one chapter on the “arms race” between pathogens and their hosts and one chapter (titled “Stop Evolution Now!”) that focuses on slowing the evolution of resistance to pesticides and other pest-control measures.

Both books (Nesse and Williams, 1994, Denison, 2012) and the earlier review articles on which they were based (Williams and Nesse, 1991, Denison, et al., 2003) devote much more space to the implications of past evolution.
“If evolution by natural selection can shape sophisticated mechanisms such as the eye, heart, and brain, why hasn’t it shaped ways to prevent nearsightedness, heart attacks, and Alzheimer's disease?”
Similarly, biotechnology allows us to increase the expression of crop genes that enhance drought tolerance, but
“mutations that increase gene expression happen all the time, and natural selection maintains those that are beneficial to the plant.  So why does corn normally have lower expression of this gene than was obtained by genetic engineering?”
We don’t have definite answers to these questions.  Both books present hypotheses with various amounts of supporting data, but additional research is needed.  With aging populations and rising food prices, maybe there will even be some money available to fund that research.  If you are an evolutionary biologist who mostly works on fundamental problems and/or wild species, should you consider adding an applied component to your research portfolio?  If so, you might get some useful ideas from Williams and Nesse or from my book, just published by Princeton University Press.

Literature Cited

Denison RF. 2012. Darwinian agriculture: How understanding evolution can improve agriculture. Princeton: Princeton University Press.

Denison RF, Kiers ET,  West SA. 2003. Darwinian agriculture: when can humans find solutions beyond the reach of natural selection? Quarterly Review of Biology 78: 145-168.

Nesse RM, and Williams GW. 1994. Why we get sick: The new science of Darwinian medicine. New York: Vintage Books.

Williams GW,  Nesse RM. 1991. The dawn of Darwinian medicine. Quarterly Review of Biology 66: 1-22.

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