Books: Why we're different from the animals

Consilience

by Edward O Wilson Little, Brown pounds 18.99

What is it with Darwinian writers? Once in a while they get stricken by a strange malady which transforms rational thinkers into ones given to endless (and often mindless) speculation; turns elegant writers into verbose ramblers; and infects them with the delusion that the answer to the world, the universe and everything will be revealed in the pages of one book - The Origin of Species. Edward O Wilson has long suffered from this malady: it is almost 25 years since his book Sociobiology: The New Synthesis introduced the word sociobiology to a popular audience and generated enormous controversy with its claim that "the social sciences, as well as the humanities, are the last branches of biology". shows that he still hasn't shaken off the bug. "It can all be explained," he claims, "as brain circuitry and deep, genetic history."

There is, in fact, much to admire about Wilson. A superb entomologist, and the world's foremost authority on ants, he is responsible for some remarkable experiments and theoretical innovations in ecology and population biology.

As two Pulitzer Prizes attest, he can be a wonderful writer, wielding his pen with intelligence, erudition and passion. But in , as in Sociobiology, his desire to tackle a "big issue" overwhelms his usual virtues. Reason becomes rhetoric, passion turns to prolixity.

The basic premise of is one for which I have considerable sympathy. Wilson is appalled at the fragmentation of knowledge and at the deep gulf between science and the humanities. He wants to reclaim the Enlightenment tradition of belief in "a lawful material world, the intrinsic unity of knowledge and the potential of indefinite human progress". This is ambitious stuff, and his optimism about human capacities is invigorating. Unfortunately, he lacks the intellectual tools to see it through.

Wilson believes that intellectual unity can be created by extending the method of reductionism, widely used in the natural sciences, to all areas of knowledge. Reductionism treats nature as a piece of machinery which can be broken up into its component parts and each part studied in isolation. The properties of the whole derive from those of its parts, and by understanding the workings of the parts we can understand the workings of the whole. Hence human behaviour can be understood by analysing the workings of the human brain, the workings of the brain understood by analysing the workings at its constituent neurones, the workings of the neurones understood by analysing their chemical and physical changes, and so on. "Total consilience," Wilson writes, "holds that nature is organised by simple universal laws of physics to which all other laws and principles can eventually be reduced."

Reductionism has been a valuable tool in extending our understanding of nature. Biologists, in particular, have made enormous gains by treating living processes as if they were mechanical ones. But how useful is reductionism in understanding higher human functions such as consciousness or artistic ability? Without question, all behaviour, whether human or animal, is associated with particular physical states of the brain. With most animals we can go further and say that these brain processes cause that behaviour. But is this true of humans? I doubt if it is in many cases, at least in any meaningful sense.

Neuroscientists, for instance, are beginning to understand the neural processes that underlie complex activities such as reading or writing. It is plausible that in time we could describe as complex an activity as writing a book entirely in neurological terms. But does it make any sense to say that such brain processes caused, say, Wilson to write ? I doubt if many people would say yes - probably not even Wilson himself. Complex human activity involves not simply physical processes, but social causes too. And while social causes impinge upon any individual through his or her brain processes, they cannot be reduced to those processes.

This is not to say that we need to invoke spiritual process to explain human behaviour - social processes are no less material than physical ones. But we need to understand that humans, while they are animals, are not simply animals and that the processes of human life cannot simply be understood in the same terms as those that describe animal life - a problem that Wilson's methodology simply does not address.

Wilson attempts to deal with the special, social nature of human beings through his notion of "gene-culture co-evolution". "To genetic evolution," Wilson writes, "the human lineage has added the parallel track of cultural evolution." There is nothing new about this - everyone agrees that humans are moulded by both genes and culture. The key question is: what do we understand by culture, and by cultural evolution? For Wilson, culture itself is a product of genetic evolution. What Wilson is talking about, therefore, is not gene-culture co-evolution, but gene-gene co-evolution. Indeed, he suggests that "gene-culture co-evolution is a special extension of the more general process of evolution by natural selection".

There is, though, a fundamental distinction between genetic and cultural evolution. Genetic evolution is blind: natural selection works to no pre- ordained plan. Cultural evolution is, however, to some extent at least, purposive. Humans make history by straining towards goals. It is a gross error to confuse genetic and cultural evolution and to assume that the latter, like the former, is driven by the blind forces of natural selection.

Wilson is not crass enough to suggest that there is a direct relationship between genes and culture. Rather, he argues that genes code for "epigenetic rules" which shape human behaviour. Some of these rules have been well worked out by psychologists and neuroscientists. A good example is colour vision. "Colour" does not exist in nature. Visible light consists of continually variable wavelengths, with no intrinsic colour in it. Humans, however, divide the spectrum into discrete units which we call red, green, blue, etc. These divisions are arbitrary but are the same for all humans. In other words, all humans must possess a set of genes which "tell" us to divide the spectrum of light in a particular fashion.

In the field of perception, particularly vision, many such "rules" have been elucidated. But Wilson wants to make a bigger claim that such rules regulate not just perception, but the way that we appreciate art, our capacity for moral thought and our tendency to be religious. The trouble is that there is virtually no evidence for any of this. As a result Wilson's arguments for the existence of such rules swing from the banal to the bizarre. He tells us that epigenetic rules for art and religion "bias innovation, learning and choice". I doubt if you needed a lifetime's study of biology to come up with such a truism.

When Wilson attempts to provide concrete examples of epigenetic rules, however, these simply strain our credulity. According to Wilson we appreciate Piet Mondrian's abstract paintings because his patterns of lines and colours create an effect "not unlike that of a mottled sky viewed upward through a woodland canopy". Hence, Mondrian "stays true to the ancient hereditary ground rules that define the human aesthetic". It is an argument that belongs more to the Eric von Daniken school of science-as-wishful- thinking than to any theory derived from Charles Darwin.

Occasionally, Wilson seems to lose the plot entirely, and descend into outright mysticism. This is his explanation of why humans are drawn to religion: "Communion is the key, and hope rising from it eternal; out of the dark night of the soul there is the prospect of a spiritual journey to the light ... The mind reflects in certain ways in order to reach ever higher levels of enlightenment until finally, when no further progress is possible, it enters a mystical union with the whole. ... Happiness [is] to find the godhead, or to enter the wholeness of nature, or otherwise to grasp and hold on to something ineffable, beautiful, and eternal." The first time I read this passage I thought I had accidentally dipped into the manifesto of the Natural Law Party.

Wilson's forays into mysticism might make more sense if we recognise that science is, for him, akin to faith. "People need a sacred narrative," he writes. "They must have a sense of larger purpose, in one form or other, however intellectualised." Such a sacred narrative, he believes, can be either a religion or a science. "The true evolutionary epic," he writes, "retold as poetry, is as intrinsically ennobling as any religious epic." From the facts of evolutionary biology "new intimations of immortality can be drawn and a new mythos evolved."

For Wilson, then, the search for the unity of knowledge is less a rational process than a religious quest driven by faith. The problem with faith, however, whether it is drawn from the Book of God or the Book of Nature, is that it often makes us blind to the facts.