Thursday, February 5, 2009

Unfinished business

Charles Darwin’s ideas have spread widely, but his revolution is not yet complete

THE miracles of nature are everywhere: on landing, a beetle folds its wings like an origami master; a lotus leaf sheds muddy water as if it were quicksilver; a spider spins a web to entrap her prey, but somehow evades entrapment herself. Since the beginning of time, people who have thought about such things have seen these marvels as examples of the wisdom of God; even as evidence for his existence. But 200 years ago, on February 12th 1809, a man was born who would challenge all that. The book that issued the challenge, published half a century later, in 1859, offered a radical new view of the living world and, most radical of all, of humanity’s origins. The man was Charles Robert Darwin. The book was “On the Origin of Species”. And the challenge was the theory of evolution by natural selection.

Since Darwin’s birth, the natural world has changed beyond recognition. Then, the modern theory of atoms was scarcely six years old and the Earth was thought to be 6,000. There was no inkling of the size of the universe beyond the Milky Way, and radioactivity, relativity and quantum theory were unimaginable. Yet of all the discoveries of 19th- and early 20th-century science—invisible atoms, infinite space, the inconstancy of time and the mutability of matter—only evolution has failed to find general acceptance outside the scientific world. Few laymen would claim they did not believe Einstein. Yet many seem proud not to believe Darwin. Even for those who do accept his line of thought his ideas often seem as difficult today as they were 150 years ago.

The origin of the Origin

The idea of evolution by natural selection is not hard to grasp. It just requires connecting some uncontentious propositions. These are that organisms vary from one another, even within a species, and that new variation can arise from time to time; that some of this variation is passed from parent to offspring; and that more individuals are born than can exist in the available space (or be sustained by the available resources). The consequence is what Darwin described in his book as a “struggle for existence”. The weakest are eliminated in this struggle. The fit survive. The survivors pass on their traits to their offspring. Over enough time, this differential transmission of characters will lead to the formation of a new species.

Darwin’s theory explained why species were so well adapted to their environment and how new species would form. It suggested that all living things were related, from the beetle to the lotus, and that everything descended ultimately from a single common ancestor. Evolution thus removed the need for divine explanations of diversity and, along with evidence emerging at that time of the extreme age of the Earth, it further suggested that the wider universe might also owe nothing to divine intervention and everything to natural laws. Darwin understood all of this and was greatly troubled.

That trouble continues today. In the United States a Gallup poll conducted last year found that only 14% of people agreed with the proposition that “humans developed over millions of years”, up from 9% in 1982. Acceptance of evolution varies around the world, with the most ardent believers being in Iceland, Denmark and Sweden (see chart). In general, as you might expect, a country’s belief in evolution is inversely correlated with its belief in God. But there is an interesting twist.

Gregory Paul, an independent researcher on evolution, and Phil Zuckerman, a sociologist at Pitzer College in California, have argued controversially that a belief in God is inversely correlated with the level of what might be described as the intensity of the struggle for existence. In countries where food is plentiful, health care is universal and housing is accessible, people believe less in God than in those countries where their lives are insecure. A belief in God, and rejection of evolution, they suggest, is most valuable in those societies that are most subject to Darwinian pressures.

Making science work

Be that as it may, many aspects of modern science could not work without accepting evolution. Darwin’s ideas touch every corner of biology and medicine. They have also had an impact farther afield, in areas from art to politics. And their impact has been practical as well as theoretical. Both software engineers and drug developers, for example, often make use of evolutionary thinking when designing their products.

Economics, too, may be helped by Darwin. Ideas about “rational” economic man are being overturned by new ones from a discipline called behavioural economics. Rather than assuming that individuals faced with economic decisions will comport themselves in what “classical” economists regard as a rational manner—ie, to maximise their future wealth—behavioural economics tries to study how real people actually behave.

What is surprising is the degree to which human beings are not rational, and how the reasons for this are likely to involve Darwinian explanations. Take, for example, a phenomenon called the endowment effect, which is the tendency most people have to value objects they already own more highly than similar ones they have never owned—and, consequently, to be more reluctant to trade them than a classical economist would predict.

Because this effect has been observed in three primate species, most recently in a study of chimpanzees, it suggests this effect has evolutionary roots. Its strength seems to relate to the evolutionary salience of the item in question. People may be reluctant to trade goods related to food and mating because in the recent evolutionary past it meant parting with a known object in exchange for an uncertain proposition.

Another example of economic behaviour that may have deep evolutionary roots is the “herd” mentality that contributes to financial bubbles. In the past, copying the neighbours would have been helpful—in order to avoid danger or to find food. In today’s financial systems, however, it can create instability. The instinct to follow the herd can be rationalised as rational, so to speak, since everybody benefits in the short term by forcing the price up. But it does not look so rational when the instability is exposed by an external shock and the market crashes. In fact, at least part of what seems to be going on is that everyone instinctively feels compelled to copy the others, rather than making an independent assessment of the situation.

Whether the mystery is why people are so averse to risk, unable to estimate the time needed for a given task, or give different answers to the same question depending on how it is framed, there is a fair chance that the explanation will, at some point, involve evolution. To understand human behaviour properly, the world needs Darwin. Some have said it is the best idea that anyone ever had. If it isn’t, it certainly comes close.

Despite so much evidence, evolution remains difficult to accept because it implies everything living is largely accidental. Stephen Jay Gould, an American evolutionary biologist, who died in 2002, argued that misunderstandings about Darwinism were rife not because the theory is difficult to understand but because people actively avoid trying to understand it. He thought a misunderstanding about progress was the problem.


Related previous post:

Why we are, as we are

Related books:

The Autobiography of Charles Darwin

The Origin Of Species

The Voyage of the Beagle

The Selfish Gene

Mean Genes
Darwin quote from Favorite Quotes post (taken from his autobiography):
"I have been speculating...what makes a man a discoverer of undiscovered things, and a most perplexing problem it is. Many men who are very clever, -- much cleverer than discoverers -- never originate anything. As far as I can conjecture, the art consists in habitually searching for causes or meaning of everything which occurs. This implies sharp observation and requires as much knowledge as possible of the subject investigated." -Charles Darwin