What is Evolution?

Evolution is the central organizing principle of biology. It essentially says that all organisms on Earth are descended from common ancestors. That means that all humans have a common ancestry, and at deeper levels we are related to other apes, other primates, other mammals, other animals, and all of life. Through the processes of variation, inheritance, and adaptation to changing conditions, the history of life has unfolded. The evolution of new species is offset by the extinction of others, as Earth’s climates and the configuration of oceans and continents have changed through time.

Everything in the Universe changes through time, and in that sense “evolves.” But only living organisms evolve through a process of variation and inheritance of those variations. Evolutionary theory today encompasses the fossil record, classification, genetics, molecular biology, biogeography, paleontology, developmental biology, and many other fields. It is one of the most active and productive fields in all of science, and has been for over 75 years.

Charles Darwin is one of the most important figures in Western thought. Born in Shrewsbury, England, in 1809, he studied medicine at Edinburgh and natural history at Cambridge. Then, at the age of 22, he was invited to join the scientific expedition of HMS Beagle on a scientific survey of South America and other sub-equatorial islands and provinces. Darwin was an assiduous collector and naturalist, and the information and specimens that he gathered gave him the evidence and the stimulus to question that “mystery of mysteries,” the origin of species. He reasoned that, just as humans have been able to select tiny variations in new generations of animals and plants, and breed them to select characteristics useful to humans, so nature could have acted on favorable variations in natural populations, weeding out the less fit and permitting the successful to reproduce more offspring in the next generation. Over time, these inherited traits would spread and dominate in the species, leading to evolutionary change.

Darwin is best known for the theory of natural selection, but he also invented the concept of sexual selection, greatly advanced the theory of biogeography, practically invented the principles of modern ecology, insisted (as biologists do today) that classifications must be based on ancestry (rather than on resemblances), and laid the groundwork for the next 150 years of biological research. He found out how coral atolls are formed, produced a comprehensive classification of fossil and living barnacles, invented sexual selection, and described the action of worms on creating soils and indeed the entire landscape of Britain. His ideas, notably natural selection and sexual selection, have influenced generations of novelists and artists, including Thomas Hardy, George Eliot, and John Fowles. His intellectual legacy is one of the most enduring in Western thought. Darwin was buried in Westminster Abbey upon his death in 1882.

What evolution is NOT: it is NOT an explanation of the origin of life. Evolution is based on genetic variation and selection among individuals in a species; the origin of life entails hypotheses and evidence about how the chemicals necessary to compose the first things that we might call “life,” as well as the formation of its hereditary material, nuclei, and other organelles, might have been assembled on a primeval Earth. Evolution does NOT depend on “random, undirected processes”; quite the opposite. Natural selection is the OPPOSITE of random processes, just as random admission to college is the opposite of a selection process. Evolution also has a “direction,” which is time: all life changes through time, through selection and other processes. Evolution is NOT atheistic: it deals only with the natural processes by which organisms change, and says nothing about supernatural entities. Scientists of all religions (and of no religion) work within the paradigm of evolution, despite their religious, cultural, and political backgrounds. Evolution is NOT tied to Marxism, fascism, or any other perceived societal evils. It is simply about biology. In fact, it has often been declaimed by Marxists and fascists, who have also seen religion as just as evil as evolution. And finally, Evolution does NOT mean we are no better than animals and we have no sense of morals or ethics. In fact, evolution says that we ARE animals, which can scarcely be denied. Ethics and morals, as humans conceive of them, are irrelevant to other species. (Is a lion “evil” because it kills and eats an antelope?) But ethics and morals can evolve like any other behaviors. Evolution does NOT mean “screw your buddy” or “everyone for himself.” That is “Social Darwinism,” which was invented by Herbert Spencer, and Darwin abhorred it. Darwin thought that natural selection ceased to exist in the origin of humans; rather, sexual selection, cooperation, and other processes explained why human society and values are so different from those of other animals. He wrote a book about this called The Descent of Man; or, Selection in relation to sex, to emphasize his point.