Richard Lewontin, a prominent evolutionary zoologist at Harvard University, argued at U of T last week that the traditional Darwinian view of organisms evolving to meet the challenges of pre-existing environments is wrong.
Lewontin spoke on Jan. 10 at Trinity College, delivering the college’s Keys Memorial Lecture. His speech was called “The Co-evolution of Organisms and the Environment.” In it, he argued organisms create their environments rather than just responding to conditions that exist independently. Living things are constrained by their environments, but as an organism evolves, its environment evolves too. The relationship between organism and environment is a two-way street.
Before Darwinian thinking, there wasn’t a firm line between living beings and the forces that shape them. “The division between living and not living was not a firm one,” Lewontin said. Darwin “alienated inside from outside” when he proposed natural variation is caused only by internal forces. An environment makes demands, but it does not cause the organism to change.
Lewontin disagrees with this Darwinian view, arguing fixed environments do not exist. Lewontin defines environment only relative to the organism being “environed.” It follows that the idea of fitness would also be a mistaken one, because it assumes the pre-existence of a niche into which an organism can fit. “The metaphors of fitness and of adaptations are the wrong metaphors.”
(At this point, a technician ran onto the stage and the audience delighted in Lewontin’s good humour as he halted his lecture, allowing the TVO technician to grope around in his pocket, attempting to fix a malfunctioning microphone.)
Organisms construct their environments, Lewontin continued, because they “determine what aspects of the world are relevant to them and what aspects are irrelevant.” For example, English thrushes often eat snails after smashing their shells on rocks. So those rocks are part of the thrushes’ environments. Other birds share the same habitat but have no use for the rocks, so the rocks are not part of their environments, even though they live side by side with the thrushes.
This happens on different scales, too. Each person lives in a shell of warm moist air several centimetres thick that is generated by metabolic processes. And there are many parasites that live within this shell. So people construct their own micro-environments, in turn influencing the evolution of parasites. On larger scales, we build macro-environments for ourselves, like clothing, buildings and cities.
Emphasizing a point he argued in his book The Triple Helix, Lewontin argued that genes, organisms and their environments cannot be understood separately. Because organisms construct their surroundings, “Environment is coded in genes. Just as the organism is made by the outside, the outside is made by the organism.” Contrary to Darwin, the inside and the outside are related.
In response to a question from the audience, Lewontin said he has little sympathy for people who want to “save the environment.” There is no such thing as “the environment” in his view.
“The ensemble of environments is constantly evolving and changing,” Lewontin said. It is only when we assert our own values—deciding that we like this set of conditions over that one—that it makes sense to talk about conservation. But conservation is not natural. Nature is constantly changing.
The most obvious example of organisms destroying their environments is, of course, humans. But trees and many other species do it too. Lewontin pointed to his home in Vermont for an example. In the 19th century, mixed hardwood forests were razed for farmland. But years later, many farms were deserted and in their place came white pines. “Organisms can be the worst enemies of their children,” Lewontin said, and white pines are among those. The offspring of a white pine cannot grow under its parent’s shade, so in the next generation, hardwoods replace the pine forests again. But the hardwoods can’t re-establish on their own, since they depend on the soil conditions the pines create. That environment is something the organisms constructed.
Another argument for the interconnectedness of organisms and their environments is what Lewontin called “time integration.” Organisms have many ways of evening out conditions—that is, of controlling their own environments—by storing energy, for example. Oaks trees store energy for their embryos in the form of acorns. And squirrels store acorns as energy for the winter. People save energy inside their bodies as fat, and outside their bodies as stored foods. In human culture, resources are also stored and transferred through money.
The bottom line, said Lewontin, is that organisms and environments are not separated the way Darwinian thinking assumes. To understand nature, we need to recognize that organisms and environments are interdependent and that they evolve together.
Photograph by Simon Turnbull
