May 22, 2013 | 13
It is in our nature to fit nature to us. We are best at it, but other species do it. This obvious but overlooked factor contradicts the dominant one-way-street gene-centric view of adaptation. A better framework for evolution is needed. Its shape isn’t clear, but it must incorporate: extracorporeal gene effects, “gene-culture coevolution,” “niche construction,” reduced randomness, and intelligent influences.
George Williams, a founder of the gene-centric school, claimed “Adaptation is always asymmetrical; organisms adapt to their environment, never vice versa.” He was wrong.
Richard Dawkins proposed the idea of “extended phenotypes”—a phenotype is the subset of an organism’s genetic traits that develop— to describe environmental changes caused by organisms. Derek Bickerton says, for Dawkins a “beaver’s dam [is] just as much an expression of beaver genes” as its tail. But that’s far from the whole tale of gene-environment interactions.
Organisms, and their genes, can face selective pressures from created elements in their environments. Intelligently created nonrandom factors have substantially altered human genes; for example, after only a few thousand years of dairying, adult lactose tolerance has spread to 98% of Swedes but just 7% of Chinese. Protocultural tool use in Galapagos finches has led to their beaks being adapted for using cactus spikes to extract grubs. Unlike Dawkins’s extended phenotypes, this “gene-culture coevolution,” as E. O. Wilson calls it, incorporates more than is in an organism’s genes, accounting for nongenetically transmitted factors like tools, rules, and socially acquired second nature skills.
Niche construction adds to genes and culture a third inheritance process: persisting ecological engineering. Many species inherit niches much modified by their ancestors. To biologists, niches aren’t just physical nooks, they’re entire ways of life. Bickerton defines three elements: habitat, nourishment, and sustaining behaviors, and says “changes in behavior trigger changes in genes at least as often” as the other way around. Evolution’s fitting and matching processes can work both ways, with complex feedback
In Niche Construction: The Neglected Process in Evolution F. John Odling-Smee and colleagues give “hundreds of examples of animal niche construction.” They say it adds nonrandom “directedness to the evolutionary process,” and that neither culture nor intelligence are needed. For example, earthworms “utilize various kinds of niche-construction” to compensate for “bad structural adaptation.” Originally water-worms, they retain ancestral traits by modifying soil to mimic features of their ancestral aquatic conditions. Even changes as radical as moving habitats from water to land can be mitigated by counteractive niche construction.
Darwin said natural selection was “not the exclusive means of modification” in evolution. Ignoring other modifying mechanisms is unnaturally selective. We artificially select factors to which we adapt. As Shakespeare put it “that art Which you say adds to Nature, is an art That Nature makes.” And many creatures are coactive partners in their dance with destiny.
Illustration by Julia Suits, The New Yorker Cartoonist & author of The Extraordinary Catalog of Peculiar Inventions.
Previously in this series: