The Trial of the Cannibal Dog by Anne Salmond<br></br>Discoveries: the voyages of Captain Cook by Nicholas Thomas

Captain Cook's legendary voyages involved encounters not just with Australia, but with surfing too. Dea Birkett rediscovers the man and the myths

I've been thoroughly Cooked. I've been tossed on the South Seas and attacked by warring canoes; admired numerous young women displaying their tattooed buttocks; and been steered around Tierra del Fuego until I feel quite seasick. Yet still, I want more. We don't seem to be able to get enough of the explorer Captain Cook and his remarkable adventures.

When should we say a subject has been overdone? There are more than 100 biographies of James Cook currently in print. Yet, curiously, one publisher, Allen Lane, has just brought out two more. Both are by scholars of the Pacific region. Nicholas Thomas and Anne Salmond, distinguished professors of anthropology, are unusually companionable for literary rivals. They refuse to be cast as competitors over Cook's image to the extent of profusely thanking each other in their acknowledgements.

Salmond says Thomas "helped to inspire" her work; Thomas says Salmond gave him "personal support". Both claim to be focusing on "encounters" - that is, the meetings between Cook and the societies he travelled among, principally in the South Seas. Neither is a cradle-to-grave biography (although Salmond does make a nod to Cook's roots as the son of a Yorkshire farm labourer); both prefer to take 1768 as the departure point. Then Cook went on his first voyage in search of the Great Southern Unknown Continent.

Both are very big books; between them they provide almost 1,000 pages on the history of cross-cultural exploration. Even historian Glyn Williams endorses Discoveries and The Trial of the Cannibal Dog on their respective back covers, as if he, too, could not bear to choose between them.

But there are marked differences, not only from each other, but from the hundreds of biographies which have preceded them. Thomas's perspective on Cook is particularly fresh. He reminds us, through stories of his own lessons as a child in Australia, how Cook is part of all our histories. Of the many biographies, a significant proportion is aimed at children, turning him into an enduring example to us all.

He is a man of whom we have all heard, and whose portrait by Nathaniel Dance we would probably recognise, but about whom, upon examination, we actually know very little. Yet I can still recall being told in my own schooldays the names of his ships - Endeavour, Resolution, Discovery, Adventure. I remember that he observed the Transit of Venus, charted unknown territory and discovered Australia. And that he was murdered by cannibals on a beach in Hawaii. The circumstances of his death seemed to sum up the encounter between the explorers and explored. The explorers were heroes, the true stuff of Ladybird books; the explored were brutal savages.

Then, I remember, some years later in my teenage textbooks, that what I was taught about Cook began to change. I was told Cook and his men were to blame for the contamination of the South Seas, both physically and morally. The seafarers were said to have brought untold diseases with them, mostly venereal, which decimated the islands' populations.

Strictly organised, societies broke down; the rot set in. Cook's so-called discoveries may have been to the advantage of Britain's expansionist plans, but not to that of the people he encountered.

Discoveries tackles this was-he-a-goody-or-baddy debate. Thomas stresses that no portrait that paints Cook as an evil imperialist can do justice, not only to his remarkable skills as a map-maker and his evocative accounts of new societies, but to his curiosity. If not always enchanted, he was enthralled by all he met, so that both Thomas and Salmond cannot resist quoting copiously from his journals.

Discoveries is not a tidy or easy book; it demands that the reader pay attention to every idea as it weaves a complicated path around the story of Cook's voyages, and the stories subsequently constructed around them. This is a complex portrait, and "ambiguous" is the author's favourite adjective.

Not only does Thomas try to show that Cook was neither good nor bad, but reveals Cook's own struggles to justify what he did in humane terms. He would swiftly punish a Polynesian for pilfering, then confess to his journal that he only did it because he felt compelled to do so, endlessly worrying whether it was the right thing. This portrait may be a more difficult to grasp than any we have read before, but as a result it is certainly more interesting. It is also more believable, as a hero is replaced by a flesh-and-blood man.

You can also dine out on Discoveries, as Thomas uncovers small nuggets of new information about old stories. "In my schoolboy sense of Cook," he confesses, "I always supposed that Endeavour was the name the captain gave the ship, a sort of emanation of the spirit that he uniquely possessed. So far as can be established, Cook had nothing to do with it ... The ship could just as easily have been called the Racehorse or even the Carcass" - the names of contemporaneous vessels which would, according to Thomas "have diminished the mythic potential of Cook's voyage."

Then comes an astonishing historical fact. Sailing back into Matavai Bay, Cook and his companion, Joseph Banks, witnessed a "truly surprising" form of local amusement. "In a high surf that, Banks judged, no European would have survived, a dozen Tahitians were swimming, and some riding the breaking waves on an old plank broken off a canoe. The 'incredible swiftness' with which they were rushed in was fantastic. 'We stood admiring this very wonderful scene for a full half hour,' Banks wrote, reporting the first European encounter with the Polynesian art of surfing."

Such details also abound in Salmond's account. But hers is a far more straightforward retelling of Cook's South Sea voyages, focusing on the collision point between two cultures - 18th-century Europe and Polynesia. She details almost every moment of contact, insisting, like Thomas, that there was both hospitality and brutality on both sides. This is a bleaker account, in that it tumbles into atrocities and the violence of Cook's death, as if they were almost inevitable.

Both books provoke. Neither bores. As these two new biographies prove, there are some subjects that can't be overcooked.

Dea Birkett's books include 'Serpent in Paradise' (Picador), about Pitcairn Island