FitzRoy, John Gribbin and Mary Gribbin

The creationist who gave birth to Darwin

The sadness of Robert FitzRoy's life lies in the subtitle of this superb and moving biography: "the remarkable story of Darwin's captain and the invention of the weather forecast". A brilliant mariner, FitzRoy was an MP, governor of New Zealand, and the pioneer of weather forecasting. Yet history has come to see him simply as "Darwin's captain", master of the Beagle and her most famous passenger. This is natural, given the importance of Darwin's time on the ship for his theory of natural selection. But John and Mary Gribbin point out that, had it not been for FitzRoy, we would all refer to "Wallacian theory", after Alfred Russel Wallace's identical ideas.

Robert FitzRoy was born into a formidable family. A direct descendant of Charles II, his uncle, Lord Castlereagh, was Britain's leading statesman during the Napoleonic era, before killing himself in 1822. His mother died when he was five. So FitzRoy's family background was troubled, though "true blue". Having served his naval apprenticeship, FitzRoy was given the helm of the Beagle after its previous commander, Pringle Stokes, shot himself in 1828.

A sensitive man, in spite of his reticence, FitzRoy worried that the shadow of depression was following him. Stokes had seen Tierra del Fuego as a place in which "the soul of the man dies with him", and FitzRoy feared that he would do likewise. Returning to London, he sought a gentleman companion to share his cabin, who turned out to be Darwin.

Their journey, which lasted from 1831 to 1836, was to define the lives of both men. As one of FitzRoy's finest achievements, it is only natural that the story of the Beagle's voyage occupies much of this book. Yet even though FitzRoy - the senior in age and rank - moulded Darwin's character in many ways, history has come to see Darwin as having priority, and as in the right. Darwin is the abolitionist, the evolutionist, the more naturally cheerful, while FitzRoy is irritable and melancholy, a creationist and defender of slavery.

It is in these political opinions that the seeds of FitzRoy's tragedy lie. Although a brilliant man, he was a staunch Conservative at a time when ideas were changing. He believed in God, duty and service. His attempts to convert the Yamana of Tierra del Fuego and the Maori exemplified his biblical literalism. Then, in 1859, he found that the bumbling naturalist from Shrewsbury had used the voyage to challenge his deepest beliefs.

By this stage FitzRoy was in charge of the fledgling Met Office, but his forecasting methods were under attack in the press. Darwin perhaps represented everything about the way that his values were being eroded. Had FitzRoy not chided him once for being the sort of person who took and never returned, and for omitting others on the Beagle in the original acknowledgements to his journal? Darwin's machinations to ensure that he - and not Wallace - gained precedence for the theory of natural selection were typical of the coming order.

Bowing to overwork, duty, and the long history of family depression, FitzRoy killed himself in 1865. On the long voyage to natural selection, he chose his own view of life to the end, rather than survive among the evolutionists.