Nobody at Stanford has done more to celebrate this Year of Darwin—marking the biologist's 200th birthday and the 150th anniversary of the publication of The Origin of Species—than Bing Professor in Human Biology Bill Durham, '71. Two of his biggest endeavors: an interdisciplinary, team-taught class called Darwin's Legacy and a 26-day Travel/Study jet tour retracing the voyage of the HMS Beagle. Marina Krakovsky, '92, interviewed him.
In an age when many people had ideas about evolution, why did Darwin get all the credit?
"Two messages made Darwin unique. First, he said that all living species had changed through time from one common ancestor—in other words, that all of life is related by descent. Darwin's grandfather, Erasmus Darwin, hinted that there was a history to life and that the mammals were somehow related to one another. But Charles applied that concept to all life on Earth. His was not just some poetic vision of an unfolding metaphysics of life; Darwin actually provided a structure, a branching tree. To see that in 1859, long before we had genetics, long before taxonomy was on careful footing, is incredible."
"Darwin's second key insight was that differential survival and reproduction actually designs organisms. This was Darwin's mechanism: the persistence of variants good at surviving and reproducing. It may seem ironic, but [Jean-Baptiste] Lamarck should be given a lot of credit too. He was among the first to say that life has a long history, just like the planet Earth. Lamarck had a goofy mechanism for how change happens over time, but he did pave the way by preparing people for the idea that organisms change over time."
Darwin had some wacky ideas, too, didn't he?
"Absolutely. For example, Darwin missed the boat on genetics. Given his own careful breeding experiments with plants, one might ask why Darwin didn't discover [Gregor] Mendel's laws. It looks like Darwin's own theory kept him from seeing the patterns. A paper earlier this year suggests that Darwin was so focused on quantitative variation and the "successive slight changes" assumed by his theory that he didn't appreciate the constant patterns resulting from his crosses. Mendel wasn't hung up on quantitative variation—he was just looking for patterned outcomes and he found them."
What else did Darwin get wrong?
"Darwin wrote of the effects of use and disuse, and thought that disuse was the way that ostriches, for example, became flightless. He really did not understand what today we call the genotype/phenotype distinction: that there's a lot of somatic change in organisms that doesn't get into the genetic line and therefore can't be heritable. Also, Darwin clearly thought that evolution would be a slow process, but we know now that natural selection can shape things quite quickly, during droughts and El Niño events, for example. We have speciation in the laboratory and changes in wild populations at rates that Darwin never dreamed possible."
You've cited a Gallup poll finding that fewer than half of Americans accept an evolutionary account of life.
"Yes, we're a country divided in three groups: those who accept an evolutionary view of life, those who reject it outright and those who don't know. Darwin Day doesn't make much headway with people from fundamentalist faiths who believe in biblical literalism. But the third group includes people who have an active spiritual life and don't see evolution as threatening to their religious beliefs. A lot of thoughtful reflection goes on there, and it's a fun group to talk with. One goal of bicentennial events is to keep that conversation going."
"Why are fewer than half of all Americans in the first group? One reason has to do with our schools. Our school districts are independent entities, so the decision about what to teach is left to individual school boards. The result is that evolution is well taught in some places, and in others it's shunned as "the E word." I have had students tell me that, at Stanford, they can talk openly about evolution for the first time in their lives. There are communities in our country that still have the kind of blinders that Darwin faced in 1859."
Does taking students to the Galápagos, as you've done, change their thinking?
"Most definitely. The first student so changed was Darwin, who set off on the Beagle voyage at age 22, the better to "study Creation." Happily, we have the notebook from his first days in the Galápagos, in which he says, roughly, "I recognize South America in this bird, and in ornithology here in general. I wonder if a botanist would." He wondered why so many Galápagos organisms are variations on a South American theme. One could always say that the Creator simply wanted some peculiar South-America-like iguanas in Galápagos, a different mockingbird species on each island, and no amphibians. It is possible to maintain such a belief with consistent effort and exceptional thinking for every species. On the other hand, Darwin realized the beauty and simplicity of a naturalistic account for the same observations. The organisms that got to the Galápagos resemble South American organisms because that's where they came from originally, and rafted out to Galápagos. They are now different because they have adapted over generations to local conditions. Amphibians were eliminated by the salt water. A visit to the Galápagos shows even orthodox believers that so many exceptions and special cases strains credulity."
Darwin was such a meticulous, humble observer throughout his career. Has something been lost now that biology has become more theoretical?
"One of the goals of the Darwin Bicentennial is to help people rediscover the wonder and delight of observing natural history. The focus on the theoretical—and the other trend in biology, the molecular—are both very well and good, but we should also remember that at the observable scale of everyday life many wonderful things happen. If we get lost in theory or lost in the laboratory, we lose contact with the beauty and inspiration of the natural world."
"One of the things I most enjoy about studying evolution is the awe and wonder of seeing organisms doing their thing in nature. What a marvelous curiosity are the bugs that mix together chemicals and excrete an explosive product in the face of their potential predators: It's wonderful to realize that the bombardier beetle too was shaped by the struggle for existence over the years. Seeing that helps one reflect on how we humans need to be stewards of the tree of life. With so many ideologies saying we are separately and specially created, people thought we were set on this planet to have dominion. Darwin says no, we're part of the big picture here."
There's a distinction at Stanford between biology and human biology. Doesn't that suggest that humans are special, and not just another branch on the tree of life?
"I was struck by something argued years ago by Professor Colin Pittendrigh, who helped found Human Biology. He said the two most important events in the history of life on Earth were the emergence of DNA—the molecule governing biological inheritance—and the emergence of language, which enabled human culture. Through language, culture provides humanity with a full second system of inheritance, which is indeed something special about us and gives culture a very prominent place in shaping our thoughts and actions. Human Biology was set up to make sure that if you're interested in the problems facing the human organism you have the tools to think about both kinds of inheritance, the cultural as well as the genetic."
"Now what's interesting to me is this: Darwin's insight generalizes at a philosophical level to the question, "What keeps certain forms of information, whether genetic or cultural, in the changing pool of such information across time?" In my own work, I've proposed that there are parallel but distinct processes of selection in both domains, genes and culture. Darwin termed his mechanism "natural selection" to make it understandable through analogy to human choice. Well, I believe that choice is the main mechanism of evolutionary change in culture."
Does a Darwinian view of culture imply cutthroat competition in social life?
"Well, it's true that there's a competitiveness involved in Darwinian processes. But what an evolutionary theory of culture espouses is not that ideas succeed and fail through the competitive strivings of their holders (although there have been times when that's happened), but that evolution happens in the abstract world of competing ideas. We should continue to sift carefully and preserve those that are in the best interests of the planet and of humanity."
