Why Evolution Matters
Hence both in space and time, we seem to be brought somewhat near to that great fact--that mystery of mysteries--the first appearance of new beings on this earth.
--Charles Darwin, Journal of Researches
In June 2004, the science historian Frank Sulloway and I began a month-long expedition to retrace Charles Darwin's footsteps in the Galápagos Islands. It turned out to be one of the most physically grueling experiences of my life, and as I have raced a bicycle across America five times, that is saying something special about what the young British naturalist was able to accomplish in 1835. Charles Darwin was not only one sagacious scientist; he was also one tenacious explorer.1
I fully appreciated Darwin's doggedness when we hit the stark and barren lava fields on the island of San Cristóbal, the first place Darwin explored in the archipelago. With a sweltering equatorial sun and almost no fresh water, it is not long before water-loaded seventy-pound packs begin to buckle your knees and strain your back. Add hours of daily bushwhacking through dense, scratchy vegetation, and the romance of fieldwork quickly fades. At the end of one three-day excursion my water supply was so dangerously low that Frank and I collected the dew that had accumulated on the tents the night before. One day I sliced my left shin on a chunk of a'a lava. Another day I was stung by a wasp and one side of my face nearly doubled in size. At the end of one particularly grueling climb through a moonscapelike area Darwin called the "craterized district," we collapsed in utter exhaustion, muscles quivering and sweat pouring off our hands and faces, after which we read from Darwin's diary, in which the naturalist described a similar excursion as "a long walk."
Death permeates these islands. Animal carcasses are scattered everywhere. The vegetation is coarse and scrappy. Dried and shriveled cactus trunks dot the bleak landscape. The lava terrain is so broken with razor-sharp edges that progress across it is glacially slow. Many people have died there, from stranded sailors of centuries past to wanderlust-driven tourists in recent years. Within days I had a deep sense of isolation and fragility. Without the protective blanket of civilization none of us are far from death. With precious little water and even less edible foliage, organisms eke out a precarious living, their adaptations to this harsh environment selected over millions of years. A lifelong observer of and participant in the evolution-creation controversy, I was struck by how clear it is in these islands: Creation by intelligent design is absurd. So how then did Darwin depart the Galápagos a creationist?
This is the question that Frank Sulloway went there to answer. Sulloway has spent a lifetime reconstructing how Darwin pieced together the theory of evolution. The iconic myth is that Darwin became an evolutionist in the Galápagos, discovering natural selection as he itemized finch beaks and tortoise carapaces, as he observed how each species had uniquely adapted to the available food and the island ecology. The legend endures, Sulloway notes, because it fits elegantly into a Joseph Campbell-like tripartite myth of the hero who (1) leaves home on a great adventure, (2) endures immeasurable hardship in the quest for noble truths, and (3) returns to deliver a deep message--in Darwin's case, evolution. The myth is ubiquitous, appearing in everything from biology textbooks to travel brochures, the latter of which inveigle potential customers to see what Darwin saw.
The Darwin Galápagos legend is emblematic of a broader myth that science proceeds by select eureka discoveries followed by sudden revolutionary revelations, as old theories fall before new facts. Not quite. Theories power perceptions. Nine months after departing the Galápagos, Darwin made the following entry in his ornithological catalogue about his mockingbird collection: "When I see these Islands in sight of each other, & possessed of but a scanty stock of animals, tenanted by these birds, but slightly differing in structure & filling the same place in Nature, I must suspect they are only varieties." He was seeing similar varieties of fixed kinds, not an evolution of separate species. Darwin did not even bother to record the island locations of the few finches he collected (and in some cases mislabeled), and these now-famous birds were never specifically mentioned in the Origin of Species. Darwin was still a creationist.2
Through careful analysis of Darwin's notes and journals, Sulloway dates Darwin's acceptance of evolution to the second week of March, 1837, after a meeting Darwin had with the eminent ornithologist John Gould, who had been studying Darwin's Galápagos bird specimens. With access to museum ornithological collections from areas of South America that Darwin had not visited, Gould corrected a number of taxonomic errors Darwin had made (such as labeling two finch species a "Wren" and an "Icterus"), and pointed out to him that although the land birds in the Galápagos were endemic to the islands, they were notably South American in character.
Darwin left the meeting with Gould, Sulloway concludes, convinced "beyond a doubt that transmutation must be responsible for the presence of similar but distinct species on the different islands of the Galápagos group." In Darwin's mind, the allegedly immutable "species barrier" had been shattered. That July, 1837, Darwin began his first notebook on Transmutation of Species. By 1844 he was confident enough to write in a letter to his botanist friend and colleague Joseph Hooker, "I was so struck with distribution of Galapagos organisms &c &c, & with the character of the American fossil mammifers &c &c, that I determined to collect blindly every sort of fact which cd bear any way on what are species." Five years at sea and nine years at home poring through "heaps" of books led Darwin to admit that, for him, "at last gleams of light have come, & I am almost convinced, (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable."3
Like confessing a murder. Dramatic words for something as seemingly innocuous as a technical problem in biology: the immutability of species. But it doesn't take a rocket scientist--or an English naturalist--to understand why the theory of the origin of species by means of natural selection would be so controversial: If new species are created naturally, what place, then, for God? No wonder Darwin waited twenty years before publishing his theory.4
From the time of Plato and Aristotle in ancient Greece to the time of Darwin and his fellow naturalist Alfred Russel Wallace in the nineteenth century, nearly everyone believed that a species retained a fixed and immutable "essence." A species, in fact, was defined by its very essence--the characteristics that made it like no other species. The theory of evolution by means of natural selection, then, is the theory of how kinds can become other kinds, and that upset not only the scientific cart, but the cultural horse pulling it. The great Harvard evolutionary biologist Ernst Mayr stressed just how radical was Darwin's theory: "The fixed, essentialistic species was the fortress to be stormed and destroyed; once this had been accomplished, evolutionary thinking rushed through the breach like a flood through a break in a dike."5
The dike, however, was slow to crumble. Darwin's close friend, the geologist Charles Lyell, withheld his support for a full nine years, and even then hinted at a providential design behind the whole scheme. The astronomer John Herschel called natural selection the "law of higgledy-piggledy." And Adam Sedgwick, a geologist and Anglican cleric, proclaimed that natural selection was a moral outrage, and penned this ripping harangue to Darwin:
There is a moral or metaphysical part of nature as well as a physical. A man who denies this is deep in the mire of folly. You have ignored this link; and, if I do not mistake your meaning, you have done your best in one or two cases to break it. Were it possible (which thank God it is not) to break it, humanity, in my mind, would suffer a damage that might brutalize it, and sink the human race into a lower grade of degradation than any into which it has fallen since its written records tell us of its history.
In a review in Macmillan's Magazine, the political economist and social commentator Henry Fawcett wrote of the great divide surrounding the Origin of Species: "No scientific work that has been published within this century has excited so much general curiosity as the treatise of Mr. Darwin. It has for a time divided the scientific world with two great contending sections. A Darwinite and an anti-Darwinite are now the badges of opposed scientific parties."6
Darwinites and anti-Darwinites. Although the scientific community is now united in agreement that evolution happened, a century and a half later the cultural world is still divided. According to a 2005 poll by the Pew Research Center, 42 percent of Americans hold strict creationist views that "living things have existed in their present form since the beginning of time" compared to 48 percent who believe that humans "evolved over time." Evolution has made news as the fight over teaching evolution has entered the courts and the school boards yet again. To that point, the Pew survey found that 64 percent said they were open to the idea of teaching creationism in addition to evolution in public schools, and more than half of those individuals said they think evolution should be replaced by creationism in biology classrooms.7
The evolution-creationism controversy is a cultural tempest in a scientific teapot--the debate is entirely cultural, even as professional scientists go about their business without giving Intelligent Design a second thought. Consider the geographic and political differences in attitudes about evolution, starting with the fact that evolution is under debate only in America (there are a few small creationist pockets in Australia, New Zealand, and the United Kingdom). And within the states, geography matters: 51 percent of Southerners accept the strict creationist view that humans were created as we are now and only 19 percent believe that we evolved through natural selection, while 59 percent of Northerners accept evolution through natural selection, and only 32 percent are creationists.
Given these demographics of belief, it came as no surprise to either conservatives or liberals when, in August 2005, President George W. Bush seemingly endorsed the teaching of Intelligent Design (ID) in public school science classes. As the story unfolded over the next two weeks, however, it became clear that the creationists, as well as many in the media and pundits on both the right and the left, had greatly exaggerated Bush's remarks. In an interview at the White House with a group of Texas newspaper reporters, Bush had said that when he was governor of Texas, "I felt like both sides ought to be properly taught." When a reporter asked for his position as president, Bush equivocated, saying, "I think that part of education is to expose people to different schools of thought. You're asking me whether or not people ought to be exposed to different ideas, and the answer is yes." Well, of course, but Bush answered a different question.
Indeed, Bush's science adviser, John H. Marburger III, said in a subsequent telephone interview with The New York Times that "evolution is the cornerstone of modern biology" and "intelligent design is not a scientific concept." He added that the president's comments should be interpreted to mean that ID might be discussed--not as science but as part of the "social context" in science classes, and that it would be "over-interpreting" Bush's remarks to conclude that the president believes that ID and evolution should be given equal treatment in public school science curricula.8
Rather than closing the controversy, Marburger's clarification helped stoke a renewed debate over whether evolution is "only a theory" and how it should be presented in the classroom. Indeed, in late 2005 the Kansas State Board of Education voted 6-4 to revise the state's science standards to include criticisms of evolution and to redefine science in a way that allows for the introduction of Intelligent Design creationism into the public school science curriculum (by deleting "natural explanations" from the definition of science). Shortly after the Kansas decision, a Bush-appointed conservative judge in Dover, Pennsylvania, ruled against Intelligent Design in a highly publicized court case. In early 2006 an Ohio board of education ruled not to include language that implies the introduction of Intelligent Design theory in science curricula. And there are at least a dozen more hot-spots around the country that will be settled by political debate, democratic vote, or a judge's decision.
But whatever happens in these politically charged skirmishes, truth in science is not determined by the vox populi. It does not matter whether 99 percent or just 1 percent of the public (or politicians) accepts a scientific theory--the theory stands or falls on the evidence, and there are few theories in science that are more robust than the theory of evolution. It took me a long time to realize this fact, for I began my career as a creationist. Saying this today almost feels like confessing a murder.
Like confessing a murder. That is precisely how I felt when I realized that my creationist beliefs were wrong and that evolution actually happened. I became a creationist shortly after I became a born-again evangelical Christian in high school in 1971 and argued the creationist case through graduate school in 1977.9 The evangelical movement was gathering momentum in the 1970s, and one of the central dogmas I took from it was that the biblical story of creation was to be taken literally; ergo, the theory of evolution had to be wrong.
Knowing next to nothing about evolution other than what I gleaned from reading creationist literature, I absorbed the arguments against the theory and practiced them on my undergraduate science and philosophy teachers. At Glendale College, which I attended for the first two years for general education requirements, I honed my debating skills as my creationist arguments were met with firm evolutionist counterarguments. At Pepperdine University, a Church of Christ institution where I finished my undergraduate degree, evolution was a nonentity as I witnessed for Christ and studied the theological underpinnings of the Christian faith. When I arrived at Pepperdine, in fact, I considered theology as a profession, but when I discovered that a doctorate required proficiency in Hebrew, Greek, Latin, and Aramaic, and knowing that foreign languages were not my strong suit (I struggled through two years of high school Spanish), I switched to psychology and mastered one of the languages of science: statistics. By the time I matriculated at California State University at Fullerton for graduate training in experimental psychology, I was ensconced in the methods of science.
In science, the solutions to problems are based on established parameters to determine whether a hypothesis is probably right or definitely wrong. Statistics allow researchers to identify an event as likely to happen 99.99 percent of the time (rejecting the null hypothesis) or as insignificant. Instead of the rhetoric and disputation of theology, there are the logic and probabilities of science. What a difference this shift in thinking makes. In graduate school, I took a bevy of courses in research methods and statistics, and for recreation I signed up for a Tuesday evening course in evolution, just to see firsthand what had us creationists up in arms. The course was taught by an eccentrically charismatic biologist named Bayard Brattstrom, who from 7 to 10 p.m. regaled his class with breathtaking discoveries from the science of evolutionary biology, and who from 10 p.m. to closing time at the 301 Club just down the street held forth on science and religion, Darwin and Genesis, and all manner of related topics, accompanied by appropriate libations.
The scales fell from my eyes! It turned out that the creationist literature I was reading presented a Darwinian cardboard cutout that a child could knock down. (For example, if humans come from apes, why are apes still around? Of course, we didn't evolve from modern apes; apes and humans evolved from a common ancestor who lived nearly seven million years ago.) What I discovered was that the preponderance of evidence from numerous converging lines of scientific inquiry--geology, paleontology, zoology, botany, comparative anatomy, molecular biology, population genetics, biogeography, embryology, and others--all independently converge to the same conclusion: Evolution happened. Why Darwin Matters is about how we know evolution happened, in the context of the challenges to evolution mounted by twenty-first-century creationists and Intelligent Design theorists.
Why does evolution matter? The influence of the theory of evolution on the general culture is so pervasive it can be summed up in a single observation: We live in the age of Darwin. Arguably the most culturally jarring theory in history, the theory of natural selection gave rise to the Darwinian revolution that changed both science and culture in ways immeasurable. On the scientific level, the static creationist model of species as fixed types was replaced with a fluid evolutionary model of species as ever-changing entities. The repercussions of this finding were, and are, astounding. The theory of top-down intelligent design of all life by or through a supernatural power was replaced with the theory of bottom-up natural design through natural forces. The anthropocentric view of humans as special creations placed by a divine hand above all others was replaced with the view of humans as just another animal species. The view of life and the cosmos as having direction and purpose from above was replaced with the view of the world as the product of the necessitating laws of nature and the contingent events of history. The view that human nature is infinitely malleable and primarily good was replaced with a view of human nature in which we are finitely restricted by our genes and are both good and evil.10
Darwin matters not only because his theory changed the world and reconfigured our position in nature, but because he launched a new and profound understanding of biology and science that has served future generations. Of the three intellectual giants of that epoch--Darwin, Marx, and Freud--only Darwin is still relevant for the simple reason that his theory was right, and the scientific evidence continues to support and refine it. In the memorable observation by geneticist Theodosius Dobzhansky, "Nothing in biology makes sense except in the light of evolution."11
Copyright © 2006 by Michael Shermer
Michael Shermer is the author of The Believing Brain, Why People Believe Weird Things, The Science of Good and Evil, The Mind Of The Market, Why Darwin Matters, Science Friction, How We Believe and other books on the evolution of human beliefs and behavior. He is the founding publisher of Skeptic magazine, the editor of Skeptic.com, a monthly columnist for Scientific American, and an adjunct professor at Claremont Graduate University. He lives in Southern California.