Charles Darwin: back for the future

Colin Tudge

This article originally appeared in LSE Magazine, Summer 1997

In April 1995, Helena Cronin, of the LSE’s Centre for the Philosophy of the Natural and Social Sciences, began the Darwin Seminars in which scientists, philosophers, and economists from both sides of the Atlantic regularly present and discuss ideas of a Darwinian flavour to a mixed audience of their peers, students and anyone passing who happens to be interested. Christopher Badcock in the Department of Sociology and Andy Wells in Psychology both run courses on evolution. Each Monday a group of Darwin enthusiasts and aficionados, including Dr Cronin, Emeritus Philosophy Professor John Watkins, and occasional strolling players such as myself, meet to discuss Darwinian ‘ideas in progress’. In short, just over 100 years after his death, Darwin has infiltrated LSE on all fronts: philosophy, psychology, sociology,and - returning his debt to Thomas Malthus - the sanctum sanctorum of economics. Why?

Well, Darwin is easy to underestimate. People seem to misconstrue his genius, how very great he was, perhaps because he seems so homely (tweedy, rich, amiable, established middle-class, pottering around Kent, surrounded by children and playing backgammon with his wife), and apparently deals in the day-to-day. His extraordinary book of 1859, On the Origin of Species by Means of Natural Selection, really was seminal - modern theoretical biology is just footnotes, with occasional noises off - but it tells of pigeons, orchids, ants and barnacles. Anyone can respond to such exemplars: our brains are geared to natural history. Really clever people, we tend to think, deal in weirdness that most of us will never grasp: Einstein with relativity; Niels Bohr with quantum mechanics and the insubstantiality of the universe. Metaphysically speaking though, and for that matter in sheer brain power, Darwin was up with the greats - perhaps, we might whimsically suggest, playing Tolstoy to Einstein’s James Joyce. Don’t be fooled, either, by his pottering; he just happened to be, by way of a hobby, the greatest field naturalist of all time, with a canny line in experiment. Of course, he makes use of other people’s observations in Origin (and gives fulsome credit) but it’s astounding how many insights are his own; from ants in Hampshire and the ‘tangled banks’ of Kent to the entirety of South America.

Then again, many of those who continue to underestimate Darwin simply misunderstand history. It is often said that, when Darwin wrote Origin, evolution was ‘in the air’. Darwin himself acknowledges many of his own predecessors in his introduction to Origin. In the 18th century his own grandfather, Erasmus, wrote of creatures emerging from earlier creatures. Jean-Baptiste Lamarck was among several biologists in late 18th-century and early 19th-century France who expounded evolutionary ideas. Patrick Matthew summarised the gist of natural selection in (bizarrely) the appendix to a book on naval timber. But none of these apparent predecessors hit the jackpot. Many (like Erasmus Darwin) felt that living things had changed over the years but proposed no mechanism, and in particular, could not explain how creatures were clearly adapted to the places where they live, shaggy where it’s cold and smooth where it’s hot. Lamarck proposed a mechanism - ‘inheritance of acquired characteristics’ - but it failed to convince at the time, and now is known to be wrong. Matthew (and others) failed to develop their ideas, perhaps because they did not perceive, as Darwin did, that to produce a theory of evolution that could be applied universally, and was robust, it was necessary to look at the natural history of the whole world, and at palaeontology (fossils played a large part), embryology, and at the homely arts of livestock breeding (the ‘artificial selection’ that gave Darwin the clue to ‘natural selection’). Darwin - like Matthew - conceived of natural selection in the 1830s; but, unlike Matthew, he realised that a single flash was not enough. Darwin knew that he could not make the case that was needed unless he brought to bear a huge weight of evidence, and thought through the minutest caveats, which is why it took him 20 years to publish. The only other biologist to grasp the full idea was Alfred Russel Wallace, but Darwin is rightly acknowledged as the greater.

For in truth, when Darwin wrote Origin, the prevailing belief among educated people - and, of course, among the uneducated - was of 'special creation’. God had simply made the creatures that we see around us in their present form and in their present locations. Adaptation was not perceived as a problem; of course God had matched the creatures to their environments. Neither was there any crude division between churchmen and scientists; most of the influential biologists of the day were creationists - opposed to evolutionary ideas - including the indisputably great Richard Owen, who coined the word’ dinosaur’ and whose ideas are still cited. Even those who did think of evolution tended to reject the notion that any one lineage could branch - so at best they envisaged that God had created a range of primordial creatures some time in the past (and the world was commonly supposed to be only about 6,000 years old) which had then all ‘evolved’ quite independently, up a series of separate evolutionary ladders.

So, as Ernst Mayr describes in Towards a Philosophy of Biology, Darwin needed to undertake three conceptually separate tasks. First, he had to show that evolution was a fact: the route by which all existing creatures had assumed their present form - which emphatically was not the common view. Secondly, he had to provide a plausible mechanism which explained change and also explained how that change led to adaptation; and he did this by proposing the mechanism of natural selection. Thirdly, he had to establish what to us now seems obvious (now that Darwin has pointed it out) but in the mid 19th century decidedly was not: that species can change. ‘Species’, in the mid 19th century was still essentially a Platonic concept; even biologists still felt that the creatures they saw around them were mere material copies of some heavenly ideal. It was inconceivable that they could change into different creatures - and indeed that a lineage could branch, with any one species giving rise to many different ones. Indeed, ‘transmutation of species’ was virtually a blasphemy. As Mayr says, Darwin’s principal battle was not with God but with Plato. But you cannot have branching of lineages without transmutation of species; and once you have branching of lineages you can, as Darwin makes explicit in Origin, envisage all creatures united in one great universal tree of life that sprung from a single, common ancestor; that eagles and oak trees are our relatives (and in fact, it now transpires, even the oaks are not so distant from us as you might suppose).

'Natural selection' was the notion that carried the day; the mechanism that made the idea of evolution plausible. The bones of the idea, as with all the greatest ideas, can be stated in a paragraph. First, all creatures are engaged willy-nilly in what Darwin called a 'struggle for existence'. The economist Thomas Malthus had pointed out at the end of the 18th century that if the human population continued to grow as it was doing, then it would soon exceed resources; and Darwin saw that this principle applied to all species. Every creature could, if unconstrained, produce enough offspring to cover the entire Earth within a few hundred years, and the fact that they do not do so shows that they are indeed held back: many more are born than live to reproduce themselves. Secondly, creatures that are ostensibly of the same general type, nonetheless vary; no two kittens in a litter are exactly the same. Inevitably, some of the variants will be better adapted to the prevailing conditions than others. The better adapted will be more likely to survive and to reproduce - Herbert Spencer coined the expression 'survival of the fittest', where 'fit' has the Victorian sense of 'apt' - and Darwin later adopted it. The survivors' offspring will resemble themselves since 'like begets like' (although the resemblance is not exact). Hence, over time, lineages of creatures become better and better adapted to their surroundings.

Darwin did not stop with natural selection, however. Indeed it has been said that after Origin, he seemed to lose interest in it; he had lived with the idea a long time, after all. He went on to consider another possible mechanism of evolutionary change - sexual selection - which he published in 1871 in The Descent of Man and Selection in Relation to Sex. Here he emphasised that sexually reproducing creatures (including most animals and plants) cannot reproduce unless they find compatible mates; and that, most obviously in the case of sentient and mobile animals, they have to attract mates. Therefore, he argued, selection will favour individuals that potential mates find most attractive. Hence, for example, the peacock's tail.

Often, the features that are most attractive to mates detract from the creature's ability to withstand the rough and tumble of everyday life: the peacock's tail does not do much for its agility, for example. Yet sexual selection may also encourage the evolution of characters that are of enormous value in other contexts - and Geoffrey Miller, now at University College London, argues that only sexual selection can explain the extraordinarily rapid evolution of the human brain. All in all, biologists are only now beginning to appreciate the full significance of sexual selection. But Darwin saw it first; and it has taken the rest of us more than 100 years to catch up.

Darwin, his own best critic, perceived the two most important flaws in his own thesis. First, he had no plausible mechanism of heredity - in particular, nothing convincingly to explain how 'like begets like' and yet gives rise to variations; and secondly, his ideas were unquantified. He felt the need for maths, and regretted his own poor numeracy. In the 140 years since Origin, these deficits have been made good - and there has also been one other enormously significant adjustment. The mystery of heredity was, in fact, effectively solved within a few years of Origin, by Gregor Mendel in a monastery in Brno, now in the Czech Republic. Mendel was the other great biological genius of the 19th century, for he did not merely put his toe in the water of genetics, he outlined the main concepts, all by himself in a greenhouse and a kitchen garden, perceiving that although he was focusing on peas (though later on many other species as well) he was dealing in universals. But Mendel was unlucky in his friends. Whereas Darwin conversed with Charles Lyell, who was older, and with his juniors Joseph Hooker and Thomas Henry Huxley, Mendel corresponded with a plodding Swiss professor called Karl Naegeli, who failed horribly to see the significance of his work.

As things turned out, Mendel's work was rediscovered in the late 1890s, and genetics emerged as a 20th-century science. It took several decades to reconcile Mendel's genetics with Darwin's natural selection but the result, known as 'neo-darwinism' or 'the Modern Synthesis', reached fruition in the 1940s and should be seen as one of the intellectual triumphs of the 20th century. Neo-darwinists essentially perceive natural selection at work upon the gene pool - the gene pool being all the genes shared by a breeding population of sexually reproducing creatures - as a result of which, some genes in the pool increase in frequency, while others are squeezed out.

Darwin's second desideratum - the need to manipulate the notions with the precision of maths - began to be tackled seriously in the 1920s and '30s by the great British biologists-mathematicians R A Fisher and J B S Haldane. But the maths that has proved truly appropriate was initiated only in the 1930s by the Hungarian John von Neumann; the notion known as game theory. With game theory it is possible to measure and compare the effects of different survival strategies - effectively to measure aspects of 'fitness'. It has occurred to me that, although Darwin was embarrassed by his own poor numeracy and was impressed by mathematicians such as his cousin Francis Galton. he perhaps felt deep down that the maths of his day simply was not able to tackle the kinds of problems he was posing. In practice, in the absence of game theory, his ideas were hijacked by dull statisticians, with their cocked-hat curves of normal distribution and the rest - a line of thinking that has led many biologists and sociologists to emphasise the differences between human beings, and has helped in some circles to give Darwin a bad name. In fact all those decades of grind can be seen as a diversion, not to say an aberration. I am sure Darwin knew in his bones that this was not the way to go.

These two 20th century innovations genetics and appropriate maths - can be seen as a fleshing out of Darwin (although of course both Mendel and von Neumann must be seen to be great in their own right). The third 20th century innovation is truly an adjustment. It concerns the level at which natural and sexual selection operate. For Darwin supposed that selection operated upon individuals; the cheetah that runs quicker than other cheetahs; the peacock with the largest tail. Late 20th century Darwinians think of selection acting upon individual genes: in this crude example, a gene that promotes swiftness, or attractiveness. This is the concept that Richard Dawkins has encapsulated as 'the selfish gene', for which the whole organism is merely the vehicle. Often there is no practical reason to distinguish between selection 'at the level of the individual' and 'at the level of the gene' . After all, a gene that makes a cheetah swift also helps it to survive and reproduce. But whereas thinking at the level of the individual works some of the time, thinking at the level of the gene works all the time; it is like the difference between Newtonian mechanics and Einstein's relativity.

But what has all this got to do with LSE- a school geared emphatically to human affairs? Well, Darwin made the general case throughout his writing that there is continuity between human beings and other animals. Of course, we are special in many ways, but we carry our animal history along with us. What's more, chapter seven of Origin is entitled 'Instinct'. Darwin never doubted that behaviour is shaped by natural and sexual selection, like hooves and wings, and teeth and claws. Put these two notions together, add in the 20th-century ingredients of genes and maths, add the further conceit of selection at the level of the gene, and we have a very powerful mechanism indeed by which to explore our own behaviour.

It seems odd that in the 1990s we have to defend the notion that human behaviour is influenced by genes, just as it must sometimes have seemed odd to Darwin in the 1850s that he still needed to defend the notion of species transmutation. Yet it still does have to be defended, and for the same basic reason; that the new notion can, in some respects, be disturbing. But the evidence now really is overwhelming. Take one huge generalisation; that in every society you examine, men prove to be more violent than women. Of course, in all societies, both men and women are profoundly influenced by environment: men in tough Philadelphia are hundreds of times more likely to commit murder than in tranquil Iceland - and Philadelphia women are many times more homicidal than Icelandic women. Indeed, Philadelphia women are more homicidal than Icelandic men. But in each of the countries (and everywhere else), the men's violence outstrips the women's many times over. In short, the difference in violent behaviour between men and women in all environments strongly suggests that this behavioural difference between the sexes lies in the genes. But the difference between different individuals of the same sex in different environments shows that genes merely provide the predisposition. No-one doubts that the environment shapes the outcome.

Excitingly, though, it becomes more and more possible to show that specific items of behaviour, including human behaviour, have a specific genetic input; most crudely, it is sometimes possible to show that particular behaviours (such as a tendency to make particular grammatical mistakes in speech and writing) are inherited according to Mendelian rules. Of course the particular genes involved have not usually, so far, been identified. But then, until the 1970s when molecular biology began to become properly on stream, no individual gene had been 'identified' at all. All genetics was inferential; genes were perceived as beads on strings. But genetics worked, nonetheless: its general models demonstrably reflected reality.

The new insights are extraordinary. Seminal is that of Professor Bill Hamilton, dating from the 1970s (and described in his brilliant Narrow Roads of Gene Land), that the phenomenon of altruism (paradoxical though it may seem) can be explained by reference to the selection of irredeemably 'selfish' genes. The point is that the gene is selfish, 'concerned' only with its own replication; but a gene that sacrifices its owner in some act of altruistic foolhardiness will be disseminated if, through the apparent self-sacrifice, it thereby enhances the survival of other individuals who contain copies of itself. Hence animals - including humans - will sacrifice themselves for their own relatives; and especially for their own children, who they know are likely to carry copies of their own genes. This is 'kin selection'; simple in principle, but once you start to apply it, remarkably powerful.

Of course, many people - including some biologists - still find, or pretend to find, such lines of thinking offensive. Invariably, however, it transpires that the detractors do not understand the arguments, or are banging some political drum of their own. For example, those who seek out the genetic underpinnings of human behaviour are sometimes accused of 'genetic determinism'; as if anyone was arguing that a gene that influences behaviour thereby 'determines' how we behave. But no-one does argue that; nobody sensible, that is, in the 1990s. To be sure, male genes predispose men to greater violence than women. But men do not have to behave badly. Environment remains crucial - compare Iceland with Philadelphia; and even in Philadelphia, everyone in principle has choice. Neither does anyone argue that' genetically predisposed' is simply a long-winded way of saying 'natural' or - still less - that 'natural' means 'morally justified'. Morality cannot be justified by predilection or predisposition, as G E Moore pointed out at the start of this century ('the naturalistic fallacy') and David Hume said in the 18th ('is is not ought'). These 'criticisms' of the modem Darwinian agenda are merely canards, easy and profitable points to argue in public.

The point of these modern Darwinian studies, in short, is to pursue the injunction etched on a temple wall in Delphi: 'Know thyself'. The aim is to trace this knowledge to its biological and even to its pre-biotic core. Sometimes we will like what we find (altruism, aesthetics) and sometimes we will not (homicide, jealousy - the entire catalogue of tragedy). But unless we know ourselves - 'what we are up against' - we cannot hope to construct human institutions, economic, political, medical, whatever, that are robust. This is what places Darwinian studies at the heart of LSE's endeavours.