Straightforward Darwin

This year is the 150th anniversary of the publishing of Darwin’s On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life. It’s useful to see that complete title (a short one, compared to some titles of his day!), as a reminder of the actual message Darwin gave us. He described far more than evolution in that astounding book. In fact, the word evolution is not even in the title. In fact, evolution had already been an accepted process for decades before Darwin published his insights. What was not understood in his time was how the process unfolded. What caused new species to appear? Why did some persevere and others disappear?

Darwin’s contribution was to achieve a brilliant synthesis of an incredibly wide range of scientific observations of the natural world that he and others had been accumulating. The time—the middle of the 19th century—was ripe for his insights to appear. Science in England was brewing some mighty potent stews, as many good minds fed off each other.

It is not easy to describe Darwin’s insight, largely because it pulls together such a wide ranging and complex set of descriptions of the variability and propagation of life on Earth. Recently I read an elegant description of Darwin’s concept of natural selection, written by Chet Raymo, an author/astronomer who has repeatedly inspired me. It’s a neat four-step summary:

1. Species are variable (there’s great diversity in the world).
2. Variations are maintained during reproduction.
3. Individuals produce more offspring than are needed for the species to survive.
4. Those individuals who are well adapted to their environment will be more likely to survive and reproduce, thereby passing on their traits to succeeding generations.

That’s it in a nutshell! Straightforward Darwin. Note that this description is of the process of natural selection, not evolution. Or put another way, natural selection is what drives evolution.

A second thing to note is that Darwin’s insight occurred long before anyone knew that genes and DNA existed. Now we know that errors in the copying of DNA—mutations—can cause these variations. We also know that once the error pops up, it gets passed on to one’s offspring—preserved in the DNA. Most mutations are so minor as to have no influence on adaptability or ability to survive. But when an important mutation comes along, it either favors that individual and all her or his progeny or condemns them. In the former case they become Darwin’s “favored races in the struggle for life.”

Life is a struggle. It’s a relentless competition that causes every critter to be constantly looking over its shoulder, seeking any advantage to stay alive. Nature weeds out those less fit, the less adaptable—continually refining, changing the balance, and spawning diversity. We have Darwin to thank for this profound insight; as well as his courage to publish and stand behind this controversial discovery. By the way, this year is also Darwin’s 200th birthday.