Martin Jones tells Chris Bunting about the event that changed the face of modern archaeology as well as his own career.

About 15 years ago, Martin Jones realised that archaeology was about to change for ever. An article published by the Egyptologist and molecular scientist Svante Paabo in Nature revealed that he had found the DNA of a mummified boy from ancient Egypt.

P??bo's identification of the boy's genetic code raised the possibility of unprecedented insights into the racial make-up and roots of the Nile valley populations, the structure of their society and the nature of their inter-family relations. Archaeologists might even be able to track viral infections through a population that died 4,000 years before.

"You could say he was underestimating the possibilities," says Jones, now a professor of archaeological science at Cambridge University and a leading figure in the biomolecular research that has transformed contemporary archaeology. "In the 1970s people were talking about the potential impact of genetics, but it was P??bo's DNA sequence that made a connection with me. That was when my jaw dropped, when I realised what could be done."

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Armed with an undergraduate degree in the natural sciences, Jones was better prepared than many archaeologists for the new departure. But he still remembers P??bo's article's discussion of "500 base-pair sequences", DNA markers and the double helix as a disconcerting bolt from the blue. "A lot of the concepts in the article were foreign. There was a lot of catching up to be done, but we knew this development was really going to be important," he recalls.

For an academic discipline dating from when General Augustus Pitt-Rivers began drawing up grandiose schemes of universal human progress from a series of digs on his Dorset estate in the late 1800s, archaeology was still living a kind of Peter Pan existence in the 1970s and early 1980s. "It certainly had more of an amateur feel about it in those days," Jones says. "We were right at the transition between a lobby group reacting to try to save remains from modern developers, and more systematic work. There was a large army of itinerant diggers and most digs were funded to save sites that were under threat of destruction."

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Jones spent much of his early career as an itinerant archaeological labourer. It was not very different from the lifestyle of a 19th-century navvy, except that the pay was not so good. It was also a world in which the enthusiast and the romantic were sometimes as prominent as the professional.

"On my first dig in Somerset, I remember there were these people floating around from the David Frost programme. There was a series of mounds where we were working. We had the rather boring idea that they were collapsed huts or rubbish huts. But they had an idea that these were sites where there had been fights with dragons in Arthurian times. They visited us daily to see if we had found evidence of magical lizards."

Jones, who traces his fascination with the past back to reading Arthurian legends as an eight-year-old and who remembers being fascinated as a teenager by the Cadbury digs exploring Arthur's court, recounts the dragon theories with amused enthusiasm and without a trace of contempt. He points out that the mainstream tradition of academic archaeology has its own long history of romanticism and wishful thinking.

For years, the subject's basic methodology revolved around searches for decorative "charismatic" objects such as pots and spearheads. "We would scrub away with toothbrushes to remove all the peat and dirt from the items we had rescued so that our newly polished objects might one day find a place in one of those museum display cases. On the basis of characteristics of those objects we might draw big arrows on the map about the progress of a civilisation, the epic journeys that people must have made to bring that pattern to where we found it.

"The only problem was that, even before the research into DNA, carbon dating was breaking in two a lot of those big arrows on the map. We were finding objects at the end point of the imagined great journey of a people before they reached halfway," he says.

More recently, archaeologists have begun to realise that the "peat and dirt" that they had for years been cleaning from their artefacts might have offered as much of a clue to the past as the objects themselves. Jones, an expert on the study of plant material, and academics such as P??bo looking into the DNA of human remains have gradually begun to discover a version of human history that is striking in its complexity.

"It is rather like what you find if you look at clear pond water through a microscope: you find that it is teeming with life. With these grand ideas of human development, researchers hope that the DNA microscope will sharpen up the detail of the picture. But if I was to generalise, what they most often find is a much more complicated reality than they thought."

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Researchers, for instance, have debunked the theories of the famous Kontiki explorer Thor Heyerdahl on the roots of Pacific islanders. Heyerdahl speculated that the ancestors of the islanders brought the monument-building civilisation of ancient Egypt across the world via America, but the DNA of modern islanders has little in common with that of native Americans.

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Inconveniently, however, the genes also sit uneasily with alternative archaeological theories that the islands were populated by a people migrating from the Asian continent. In fact, the Asian roots of the islands' languages, crops growing on the islands that appear to come from the Americas and gene profiles heavily marked by characteristics of the population of the Melanesian islands (30 per cent have European genes, presumably by way of relatively recent visits by sailors) are testimony to a more muddy history than the grand theorists would like.

So should the romantics pack their bags and leave archaeology to the data collectors? Jones laughs: "There will be interesting stories to tell. There was some recent work in Japan that was looking at a burial ground. They found hunter-gatherer and farmer DNA mixing in a main mound - which undermined theories that the hunter-gatherers had been pushed out by the rice growers - but they also found a smaller, obviously prestigious burial site with a young girl in it. She had completely different DNA from the rest. Then they found another grave away from the mound, obviously an outcast grave, containing another girl with similar DNA to the first. We can track individuals like that. Had these girls, perhaps sisters, travelled from a long way away? And why were their fates so different?"

Martin Jones's The Molecule Hunt , an account of the development of DNA archaeology, is published by Penguin, ?10.99.

Was Jersey bull's ancestor something of a fat cow?

Next time you meet a Scottish highland cow or a Jersey bull, remember there may be more to it than meets the eye.

In 1495, printer Johann Pruess published an account of a type of cattle then wandering Europe: "Urus are wild cattle so strong that they can lift trees as well as armed knights with their horns. They are called urus from the Greek word oros meaning mountain...these animals are nearly as large as elephants: in appearance, colour and form they are like cattle."

Ultimately, all cattle are descended from wild beasts such as urus (also known as aurochs), but DNA researchers have found surprising genetic complexity among the species.

Indian cattle, for example, are as genetically different from cattle breeds in the rest of the world as they are are from bison. The split may have happened more than 1 million years ago. Their only cousins appear to have arrived in Africa about 2,000 years ago - a mystery in itself.

Among European cattle, gene studies have shown quite close similarities among breeds such as Charolais, Simmental and Friesians. But breeds from Britain and the Channel Islands display characteristics in their maternal DNA that tell of roots totally outside the mainstream European tradition.

One theory has it that British breeds trace their roots to an earlier wave of cattle that was overstamped, but not completely erased, by the mainstream European herds. A more intriguing alternative is that a proto-Friesian bull became entranced by a mighty female auroch, thus leading to our island's unique contribution to the genetic diversity of cattle. A brave bull, indeed.

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