Jean M Auel:'What prehistoric attitudes towards sex!'

The 'Clan of the Cave Bear' author is happy to share her research into Cro-Magnon love lives with James Kidd

'Where does a caveman go for lunch?" It sounds like the first half of a playground joke. But when the question is asked by the novelist Jean M Auel, it reflects an obsessive quest for knowledge that has lasted 35 years.

Her answer, to this and many other prehistoric quizzes, can be found in Auel's blockbusting Earth's Children series about a young girl, Ayla, growing up 18,000 years ago. The sixth and final part, The Land of Painted Caves, will only increase Auel's already astonishing 45 million sales.

We talk at her London hotel. The good news is that the 75-year-old resident of Portland, Oregon is alive and well. Auel's continued existence has occasionally been the topic of debate: her last novel, The Shelters of Stone, was released amid rumours of her recent or imminent demise. "I'm not dead," she sighs. "I didn't get a divorce. I didn't fight with my publishers. I didn't have a nervous breakdown." I ask for the weirdest story she has encountered. "That I was killed by farm equipment," she laughs.

It's safe to say that Jean Auel is not your average author. She might look like a hippy ideal of grandmotherhood, but her years spent investigating primitive humankind ensure that our conversation heads down several esoteric avenues: markings on horses' teeth, prehistoric attitudes towards disability, and arguing competitions in the Arctic. Auel's conversation combines an academic's pedantic passion for the arcane corners of her specialist subject with a storyteller's desire to communicate them as dramatically as possible. It isn't always clear, however, where the anthropologist ends and the novelist begins. A question about Cro-Magnon crime and punishment inspires a ghoulish tale of an Eskimo found guilty of selfishness: the miscreant stole strips of meat from his tribe's store of liver; the tribe's solution was to swap their usual liver with cuts from a polar bear. Because polar bears are so carnivorous, their livers are rich enough in vitamin A to be poisonous. "That was the tribe's way of dealing with a selfish man. If I could have used that directly, I would have," Auel adds rather wistfully.

The idea for the Earth's Children series struck in 1977, when Auel was 40 years old. Married at 18, she had five children by the age of 25. A member of Mensa, Auel also earned an MBA and pursued a successful career in a technology firm. (She worked alongside her fellow novelist, Ursula K Le Guin.) Given this hectic schedule, it is perhaps unsurprising that Auel struggles to explain exactly where Ayla came from. "It was a story I needed to write. It captured my attention. It was the research that stimulated the imagination."

Auel's learning is prodigious. She estimates that her library holds 2,000 to 3,000 volumes, and about the same number of articles and periodicals, sent mainly by admiring academics. An amateur anthropologist she may be, but Auel has become a respected expert in her field. Nevertheless, in order to put convincing flesh on her characters' bones, Auel could not bury her nose in a book. Discovering what cavemen had for lunch required that she follow in the footsteps of modern hunter-gatherers. (Auel can recommend a recipe from Aborigine and Inuit culture: meat pounded into crumbly pieces, then formed into patties with clear fat and berries.) She took classes in survival techniques, camping out on Oregon's Mount Hood at the height of winter. "I told my husband we were spending a night on the mountain learning how to build snow caves. He said, 'Oh you are, are you?' I said, 'Yes, we are'."

For The Land of Painted Caves, Auel walked the network of decorated caverns at Les Eyzies and Lascaux in southern France. This became the route Ayla follows on her own prehistoric version of On the Road. Mixing sex, drugs, art, mysticism and a great deal of walking, Ayla explores what it means to be a mother, a woman, a healer, an artist and a hunter in her primitive society.

Fans of Earth's Children will be relieved to learn that there are also a couple of Auel's trademark sex scenes. Apparently, her husband was a more than willing participant in this research project. "I attack him for three days!"

Sex turns out to be central to The Land of Painted Caves: "What does a Cro-Magnon woman do if she finds herself pregnant, but doesn't know the cause? Was it because she bathed in a stream, ate certain foods or had relations with a man?" That they are involved in human reproduction may still be news to certain 21st-century males, but in Auel's time, the information is world-changing. It forms the foundation for monogamous relationships and the family unit

For Auel, intimate scenes offered insights into her characters. "I was trying to make sure these were people you would understand on a personal level. I look at today's world, for instance Muslim women, and don't understand a culture in which women are covered up and not treated equally. But if I watch television and see a Muslim woman grieving because she's lost her son, I can understand that. Who can't?"

Auel insists that early human tribes were actually rather enlightened about female equality, and whether she is hunting or gathering, healing or loving, Ayla can be read as a proto-feminist hero. "Women do have power and respect in most hunter-gathering societies," Auel says. "Because of the contribution they make to the society."

Although Auel clearly enjoys and even admires aspects of the pre-historic world, she has little nostalgia for the period. She might point out that early human brains were probably larger than our own; mourn the harm we have inflicted upon the natural world; and criticise some of the contemporary world's supposed technological advances, but she has no illusions about the fact that existence for her Earth's Children was nasty, brutish and short. So when I ask whether she would swap today for her prehistoric yesterday, her answer is clear: "I wouldn't want to live then ... but I would sure like to visit. Just so long as I could come back and take a hot shower."

'The Land of Painted Caves' By Jean M Auel (Hodder & Stoughton £19.99)

"Ayla looked up at him, a slow smile showing her response. There was a time when the size of his member had frightened women, before they knew with what care and gentleness he used it. His first time with Ayla he was afraid she might be nervous, before they both understood how suited they were to each other. Sometimes Jondalar really couldn't believe how lucky he was. Whenever he wanted her, she was ready for him. She never acted coy or disinterested. It was as if she always wanted him as much as he wanted her."