Like all world-changing ideas, Darwin’s concept of evolution is elegant in its simplicity. It follows from four uncontentious premises: Organisms vary from one another, even within a species; new variation spontaneously arises from time to time; variations can be passed from parent to offspring; and more individuals are born than available resources can sustain. The consequence is the “struggle for existence.” The weak die. The fittest survive to reproductive age and propagate their advantageous traits. Over time, differential gene transmission leads to the proliferation of those individuals best adapted to their environment and ultimately to the creation of new species.
Darwin was not the first to recognize these simple ideas, he just connected the dots. As far back as 490 B.C., the Greek thinker Empedicles suggested that natural selection might explain animals’ adaptations to their surroundings. In 776 A.D., Muslim theologian Al-Jahiz first described the struggle for existence as part of his early theory of evolution. Not long before Darwin’s time, Jean-Baptiste Lamarck, a French naturalist, recognized the mutability of species and proposed that traits could be inherited. Lamarckian evolution, once widely accepted, was a nice idea. But the central theory of use and disuse — that individuals develop traits that they need in life, shed unnecessary traits and pass these traits on to their offspring — was erroneous because acquired characteristics cannot be transmitted in this way.
In his 1798 essay “On the Principle of Population,” British economist Thomas Malthus argued that natural populations grow at an exponential rate while the increase in food supply is linear. In effect, many more individuals are born than can possibly survive. After reading Malthus for amusement, Darwin saw that “under these circumstances favorable variations would tend to be preserved, and unfavorable ones destroyed.” This was the selective mechanism that Lamarck had failed to see, and it formed the keystone of the idea he termed “natural selection.”
For the next two decades, Darwin collected evidence in support of his theory from every corner of the natural world. In the meantime, Alfred Russel Wallace, a British biologist, independently dreamed up natural selection, also after reading Malthus. When he heard of Wallace’s work, Darwin, afraid of being forestalled, submitted a paper to the Linnean Society of London. Armed with his wealth of data, Darwin beat Wallace to press by penning the magnum opus, “On the Origin of Species,” the following year.
Darwin’s theory explained why species were so well adapted to their environments and offered a mechanism for the formation of new species. It suggested that all life, from the humble banana slug to the raucous chimpanzee, descended from a common ancestor. Evolution thus removed the need for divine explanations of diversity and origin. Creatures, including humans, now owed their unique existence to natural laws, not divine intervention. After all, making an exception for one species is to deny Darwin’s understanding of all living things. Darwin’s insight simultaneously spawned the field of evolutionary biology and a world of religious debate.
That debate rages on today. In 2008, just 14 percent of the American public believed that “human beings developed over millions of years” without divine intervention, up from 9 percent in 1982. By contrast, more than three-quarters of Swedes, Danes and French accept that proposition. As you might expect, acceptance of evolution is inversely correlated with belief in God. Darwin’s ideas shook man from his comfortable perch above a carefully designed, harmonious world. It is hard to accept that our existence is an accident of random processes governed by nothing but the ruthless struggle for reproductive success.
Even so, Darwin’s ideas reach every corner of modern society, from art to politics. His impact on biology and the philosophy of science needs no mention. In the 50 years following “On the Origin of Species,” words used in evolutionary biology — “adaptation,” “formalism” and “functionalism” — cropped up with as much frequency in Western architecture and design. Capitalism is the economic application of natural selection. Gamers embraced “Spore,” a 2008 videogame based on a mutilated concept of evolution. Villains put evolution to more sinister ends: social Darwinism was a central pillar of Fascism and Nazi ideology, illustrating the danger in fetishizing Darwin.
As revolutionary as he may have been, our obsession with Darwin is unhealthy. He should not be the lightning rod and whipping boy for evolution. One man and one book — Darwin and “On the Origin of Species” — sounds too much like one man and one book — Jesus and the Bible. Darwin should be honored and admired like Einstein and Newton, but Darwinism is a term that should be dropped. Calling natural selection “Darwinian” evolution is like calling airliners “Wrightian” planes. It is misleading and perpetuates the notion that the field of evolution is something that hasn’t changed since the 1850s.
Darwin is closely identified with evolution. But to equate evolution with Darwin is to ignore 150 years of discoveries, including the bulk of our knowledge about evolution. For example, Gregor Mendel’s peas identified genetics as the mechanism for heritability. Watson and Crick gave genetics a mechanism by discovering DNA. The list goes on. Some of the most interesting disputes in modern evolutionary biology concern the validity of “non-Darwinian” evolution. Equating Darwin with evolution stifles earnest debate. By propounding Darwinism, we perpetuate the notion that Darwin was the beginning and the end of evolutionary biology.
Darwin was an amazing man and deserves our applause and gratitude. But tying evolutionary biology to Darwin by name and ideology impedes science. Science has marched on. Last week, we celebrated Darwin’s 200th birthday. The man had his day; here’s to moving on.