In Memory of Bill Hamilton

Biologist who died after Congo expedition was leading Darwinian theorist who explained how natural selection acts on social behaviour

Alan Grafen, Thursday 9 March 2000, The Guardian

Bill Hamilton, who has died aged 63 after weeks in intensive care following a biological expedition to the Congo, was the primary theoretical innovator in modern Darwinian biology, responsible for the shape of the subject today.

Educated at Tonbridge school, he came across RA Fisher's Genetical Theory Of Natural Selection while a Cambridge university undergraduate. When he prompted one of his tutors about the book, he was told it was mistaken and that the author, still then lecturing in Cambridge, had "no standing to write about biology".

Bill was captured by the intellectual excitement of this remarkable book, and spent his working life pursuing its line. In so doing, he provided the conceptual foundation for our understanding of how natural selection acts on social behaviour, opened up the area of "extraordinary" (that is, unequal) sex ratios, transformed thinking on sexual selection and produced a corpus of work that demonstrates the capacity of parasite-host interactions to support the maintenance of sexual reproduction. These are the primary Darwinian themes of the second half of the 20th century, and can be understood only in the context of Bill's contributions. He, like Fisher before him, took many steps at once away from conventional paths, and found that eventually biologists would change their conventions.

The career of a typical Hamilton paper can be caricatured as follows. In review, it is panned by referees who demand shortenings and revisions. Immediately after publication, it attracts criticism for obscurity. Its significance slowly emerges through secondary works, further work is inspired, and one or more literatures develop around its themes. Later more mathematical work may even be rather patronising about the paper, and emphasise discrepancies, while the primary finding is that the original idea is abundantly confirmed. The original paper is frequently, indeed often obligatorily, cited in papers in the new literatures, but is not read nearly as often as it deserves to be, since it retains a reputation for obscurity. The joy of reading the original paper is becoming aware of remaining steps.

We can look forward to decades of catching up with Bill's biological thoughts. He fused mathematics and natural history. He had a vast personal knowledge of insects and was pretty good on plants too. He kept a vast card index system. He once led an expedition through Wytham Woods, near the village where he lived, and showed an entranced audience the range of organisms that lived in rotting wood in which, he believed, most important events in insect evolution had occurred.

He loved living in Wytham, latterly with his partner Luisa, an Italian journalist. He gave dinner parties during the periods Luisa was in Oxford to spare guests his own cooking, and they were charming hosts.

Much of his thinking was mathematical in nature. He covered pages in algebra, and often drew scribbled diagrams to help his line of thought. His grasp of biological theory was extremely firm, and all his major works draw on mathematical structures. There are many biologists who are better mathematicians, but Bill more than made up in vision and purpose for any lack of formal skills. To take one example that will appeal to recreational mathematicians, his paper Geometry For The Selfish Herd is based on the idea that herds of animals are arranged on the principle that each individual tries to maximise the chance that, if a predator appears at random and strikes at the nearest prey, somebody else gets eaten. He saw genes everywhere. On a train in New England in 1980, he pointed out clumps of sumac trees. Some had smooth crowns over the whole clump, while others had furrows between individual trees. He was sure that furrows existed between genetically different trees, while trees from the same clone had a smooth crown. Everything he saw in nature was viewed through a genetic lens.

He was a lecturer in genetics at London university's Imperial college from 1964-77, a professor at Michigan university from 1978 to 1984, and then became a fellow and later a research professor of the Royal Society and fellow of New College Oxford. He received many international scientific prizes, but the time-scale of recognition led to difficulties.

In his early life, when none of his work was properly recognised, he even doubted his sanity, as he reports in the first volume of his collected papers (Narrow Roads Of Gene Land). Later, he had difficulty obtaining grants and publishing papers. The time-lag could have entertaining consequences, which occasionally gratified Bill.

The authors of one paper who made rather patronising comments waited 15 years to find the criticised theory accepted as commonplace by their own graduate students. Bill's world had different theoretical presuppositions to the worlds of those around him, and a far-seeing prophet can be a poor teacher. He would often speak so quietly that only the front couple of rows could hear properly. If supplied with a microphone, he would often speak more quietly to maintain the same level of general inaudibility. More than once, I have seen him stop in front of a slide with a graph on it, and become so engaged in contemplation of a particular data point that he grew oblivious of the audience. On the other hand, even these talks were inspiring to the few. And sometimes Bill would prepare a lecture that inspired everyone.

At the end of one such talk at the Royal Society, he showed a slide with a male and female parrot, one bright red and one bright green. Conventional theories could explain why one sex was bright, but not why both were. He ended: "When I understand why one sex is red and the other green, I will be ready to die," and seemed to mean every word.

He often referred to his own death. He said to me that he would not grow old, both in discussions of his paper on senescence ("I feel bucked when anyone refers to that paper") and discussions touching on personal safety. He refused to wear a cycle-helmet, even once they became fashionable and he had been thrown from his bike through a car windscreen. He fantasised in print about being buried by one of his favourite organisms, burying beetles, in his favourite place, the Amazonian rain forest.

In late 1999, Fisher's Genetical Theory was republished, and Bill supplied three paragraphs for the back dust-jacket. After blaming the book for his second class degree, he moves on to ask whether "by the time of my ultimate graduation, will I have understood all that is true in this book, and will I get a first?".

The circumstances of his last fatal expedition are characteristic. He became interested in the theory that HIV arose through poorly conducted vaccination trials in Africa in the 1950s, and felt this theory received less attention than it deserved because of entrenched interests in the medical establishment. The implications of this theory for xenotransplantation are very serious. He went to the jungle to collect chimpanzee faeces with the aim of finding a related virus, and testing whether it was very close to the human virus. While there he contracted malaria, and then collapsed after returning to London. He lived for ideas, was especially partial to unpopular ideas, and thought little of his own safety. His focus of interest was always genes, and it was genes he went to collect.

He was separated from his wife Christine, who he married in 1967. She and their three daughters survive him, together with his partner Luisa.

William Donald Hamilton, biologist, born August 1 1936; died 7 March 2000