Henry Walter Bates(1825–1892)

Henry Walter Bates was born at Leicester in February 1825, eldest son of a hosier who ran a stocking-frame workshop in the town. Apprenticed to the knitwear trade at thirteen, he educated himself in the evenings at the Mechanics' Institute, was collecting beetles on the canal towpath by sixteen and corresponding with the Linnean Society by nineteen. He met Alfred Russel Wallace, then a schoolmaster in Leicester, at the Mechanics' Institute library in 1844; the friendship that resulted was the foundation of both their careers.

Bates and Wallace resolved to fund a natural-history expedition to the Amazon by selling specimens to British museums and collectors. They sailed from Liverpool aboard the Mischief on 26 April 1848 and reached Pará at the mouth of the Amazon on 28 May. Bates was twenty-three. They worked together for the first eighteen months, then parted by agreement so each could cover the river's tributaries on his own line. Bates stayed.

He worked the Amazon for eleven years, from Pará up to Santarém, then up the Tapajós into the Mato Grosso interior, then back to the main stream and up the Solimões to Ega on the upper Amazon, where he based himself for four years of collecting trips into the Japurá, the Içá and the Tonantins. For most of that time he was the only European on the upper Amazon. He learned the Lingua Geral trade pidgin and conversational Portuguese, and shipped home fourteen thousand species new to science, mostly insects, the largest single collection by any one collector of nineteenth-century natural history.

He came home in 1859, sat down to write up the field notebooks, and in 1861 read to the Linnean Society the paper that gave evolutionary biology its first independent field-evidence: Contributions to an Insect Fauna of the Amazon Valley. It described what is now called Batesian mimicry, by which an edible butterfly species evolves the wing pattern of a separate inedible species the local birds have learned to avoid, gaining the protection without the cost. The mechanism required natural selection as its engine, and Bates said so. Darwin, who had been corresponding with him since 1860, called it one of the most remarkable and admirable papers he had ever read. The two-volume narrative The Naturalist on the River Amazons (1863) is the foundation document of English-language Amazonian natural history.

On Darwin's recommendation he was appointed assistant secretary of the Royal Geographical Society in 1864 and held the post for twenty-eight years, administering the Society's expeditionary work through the great age of African and Arctic exploration. He married Sarah Ann Mason of Leicester in 1861 and raised four children at Dulwich. He was elected a Fellow of the Royal Society in 1881 and died at Dulwich on 16 February 1892, sixty-seven years old. The Bates name in its English form, the patronymic of Bartholomew compressed into the northern genitive, sits in the Cumbria-to-Humber belt; he carried it from a Leicester knitwear warehouse into the foundation period of evolutionary biology.