I recall a seminar a few years ago at the Santa Fe Institute, the world's first centre for the study of complexity, which he helped to found in 1984. One speaker had been discussing some modern insights into the nature of quantum uncertainty, which prompted a query from the scientific audience: 'I wonder what Einstein would have made of this issue were he alive today?' (Albert Einstein was gravely troubled by the probabilistic nature of quantum theory.) Suddenly, Dr Gell-Mann's voice boomed from the back of the hall: 'If Einstein were alive today he'd be over 110 years of age. I think it's unlikely he'd have had anything sensible to say]'
Dr Gell-Mann's new book, The Quark and the Jaguar, isn't a chatty autobiography, it is a major work intended to convey in a reasonably non- technical way the connections that link what have been his two preoccupations: the study of the fundamental laws of particle physics and the study of complex phenomena such as the behaviour of living organisms and the development of human culture.
Murray Gell-Mann, born in 1929, was the younger of two sons of immigrant Austrian parents, and he grew up in New York. When he went to Yale, at the age of 15, he wanted to study archaeology or linguistics, but his father said that if he did he would starve. He suggested a more practical subject. Murray opted for physics to keep his old man quiet. But he quickly found that university physics was far more compelling than the physics he had done at school. He got hooked.
In 1963, as a 33-year-old professor at the California Institute of Technology, he predicted the existence of the quark, the particle of which all nuclear matter is composed. The idea, he says, wasn't hard to think of, but it required a major leap in that one had to accept we would never be able to see quarks directly. They are confined within particles such as neutrons and protons by infinitely strong forces, so it is impossible to extract a single bare quark. For this and other related work Dr Gell-Mann was awarded the Nobel prize for physics in 1969.
The all-embracing attempt to understand the universe in terms of its underlying laws is represented by the 'quark' in his book's title. The jaguar, on the other hand, enters the scene as a result of a chance encounter Dr Gell-Mann had with a jaguarundi while walking through a rainforest in Equador, and it symbolises the new direction he took in the Eighties when he renewed his interest in subjects that had so captivated him as a child - ecology, biological evolution and human culture.
He began to think that there might be unifying principles in the social and biological sciences to be found in the notion of 'complex adaptive systems'. 'These include such diverse processes as the origin of life on Earth, the behaviour of organisms, and the behaviour of investors in financial markets.'
One of the most interesting things to have emerged from Santa Fe and elsewhere has been the fact that it is possible to program computers with very simple sets of rules and produce remarkably complex behaviour. It has even been possible to simulate whole populations of evolving 'organisms' inside the silicon brain of a computer, triggering intense interest in 'artificial life', a new species of research that threatens to invade the derelict wastelands of artificial intelligence.
In his book, Dr Gell-Mann spells out what he perceives to be the flaw in much of today's social and behavioural science. 'I have always been astonished by the tendency of so many academic psychologists, economists and even anthropologists to treat human beings as entirely rational. My own experience has always been that rationality is only one of many factors governing human behaviour and by no means always the dominant factor.'
It is in the realm of protecting biological and cultural diversity that Dr Gell-Mann perhaps wanders farthest from his base camp in fundamental physics. Such diversity arises in the first place, he argues, because complex adaptive systems display a general capacity to spawn new kinds of complex adaptive systems - an early conclusion of the Santa Fe work. 'The nearly four billion years of biological evolution on Earth have distilled, by trial and error, a gigantic amount of information about the different ways for organisms to live. Both biological and cultural diversity are now severely threatened and working for their preservation is a critical task.' It seems that even Dr Gell-Mann can't help feeling that complex adaptive systems, like jaguars and human societies, are more than the sum of their parts.