At the outset, let me put my cards on the table. Creationism and Intelligent Design are junk science bunk and will not be mentioned again in this essay.
My concern here is the use and abuse of evolution in biology and a recent review by science journalist Nicholas Wade of the New York Times, the review an essay about a new book by the British ethologist and biologist and sociobiologist Richard Dawkins. It's a good and interesting review by Wade, and I recommend it to everyone. But Wade makes one point at the very beginning of his piece that is more or less a summary of what has been his mantra at the New York Times for many decades (I've been reading him for more than forty years, since he started writing at the journal Science), and a summary of what sociobiologists and evolutionary psychologists still believe. Because I think this mantra by Wade and others has perverted the intellectual atmosphere far too long, I feel compelled to respond to it. Wade says: The theory of evolution does explain everything in biology. The phenomena that Darwin understood in broad brush strokes can now be accounted for in the precise language of DNA. And although biological systems have attained extraordinary levels of complexity over the passage of time, no serious biologist doubts that evolutionary explanations exist or will be found for every jot and tittle in the grand script."
"Every jot and tittle in the grand script" means everything -- form, function, and behavior.
Yes, Darwin did believe this (DNA and genes of course unknown to him), and he made his belief, even for the human species, explicit. But the belief (and Wade's statement) is an error, and those who think it's accurate, in Wade's own idiom, have their knickers twisted.
Biology is the branch of science concerned with all living systems, including humans. Darwinian evolution is a grand theory that Darwin proposed to explain the diversity of form and function and behavior in all living systems -- including humans. Darwin proposed that the essential mechanism that operates to produce diversity is natural selection, a process that he recognized requires many thousands and usually millions of years to produce significant changes in form and function and behavior.
The word "form" is easy -- it means structure. The word "function" is more complicated and involves a degree of human arbitrary description. We consider the "function" of the human heart is to distribute oxygenated blood throughout the body. Four hundred years ago, before the circulation of the blood was understood, the function of the heart was described as something else. DNA was discovered in the 19th century, assigned a debatable "structural" function, but its current ascribed function as the genome carrier was not proposed until well into the 20th century. The glial cells of the human brain were discovered in the early 19th century, and for more than a hundred years were considered to do nothing but mechanically support the neurons they surrounded -- "stutzfunktion." We now realize that glial cells, the majority cell type in the human brain, are involved in nearly everything happening chemically and physiologically in the brain. Examples like this are easy to find.
So much for function. Now what do we do about "behavior"? Behavior is less abstract than function. It's action that we sense, or action sensed by our devices. But like function, "behavior" is not easy. Our definitions change with time, change with our insights, change with our instruments. Descriptions of the behavior of the simple protozoan Paramecium in the 19th century differ markedly from the way we describe that behavior today.
And humans? Let's cut to the chase. If we consider human behavior -- especially human social behavior, for example, the details of the origin and process and outcome of the First World War -- anyone who thinks they can explain those details with the theory of evolution has -- to use Wade's idiom again -- their knickers twisted.
One may as well propose explanations of the First World War using quantum mechanics. Sure, the electrons and quanta and vibrations were there, but try using them to explain the battles at Ypres.
Or try the relatively simple problem of explaining the social change in America from 1958 to 1968, a meager ten years that saw American society nearly turned upside down. Can the change be explained in detail by Darwinian evolutionary theory? Was the change produced by "natural selection" operating during that ten-year period?
The intellectual difficulty is that human social behavior is like an opera. Evolution provides the floorboards, but the arias, the drama, the story are most directly understood in terms of culture and history -- not in terms of Darwinian evolution. The emotions in the audience created by a scene on a movie screen are most directly understood in terms of culture and history -- not in terms of quantum mechanics and its elaborations that produced the images. The emotions produced by music cannot be understood in terms of the physics of the mechanical vibrations of musical instruments -- especially not the changes in such emotions from one generation to the next.
Evolution may be an ultimate cause of many biological phenomena, but in human affairs it's usually not a proximal cause, and the difference is very important if you want an approach that's useful. Ultimate causes are hardly ever useful explanations or sources of prediction. The ultimate cause of all life on Earth is the energy received from the Sun, and the ultimate cause of that energy is quantum mechanics--and the ultiimate cause of quantum mechanics as the modus operandi of the Cosmos was maybe the nature of the Big Bang. None of these ultimate causes can be used to predict human events--they can be used only as anthropomorphic philosophical descriptions. Evolutionary theory is of no use in predicting whether or not a particular schizophrenic patient will commit suicide--or whether country A will attack country B.
We humans are indeed biological systems and grand schemes about us are always seductive. The sociobiology grand scheme was seductive 35 years ago when first proposed. It's no longer so seductive for many people, but it still floats around here and there. Nicholas Wade's idea that the theory of evolution can explain everything in biology is, when applied to humans, a restatement of sociobiology and just as problematic.
Darwin's theory is not "wrong" -- it underlies all biological phenomena. But for human social events, it just has limited explanatory scope. So what? Every theory has limited explanatory scope. The social sciences, the studies of the various behaviors of that most complex living system -- the human species -- are not a reasonable target for explanations based on Darwin's theory of evolution -- and, contra Nicholas Wade, no serious biologist believes otherwise.