Henry Walter Bates (1825-1892) was an English explorer and naturalist. His fame rests principally on his zoological work, especially his insect collection, and his discovery of the principle of mimicry.

Henry Bates was born in Leicester, the son of a manufacturer who intended him for a business career and apprenticed him to a hosiery maker. Bates had little formal education, but the Mechanics Institute in Leicester had a good library and offered evening courses. By attending the courses and reading, Bates learned Greek, Latin, French, draftsmanship, and composition. His growing interest in Zoology led him to spend his holidays roaming the countryside and collecting specimens.

In 1843 he met Alfred Russell Wallace, who later hit upon the idea of evolution and natural selection independently of Charles Darwin. The two young men decided to visit South America in the interest of science, but they were not able to leave until 1848 because of a lack of means. They arrived in Belém, Brazil, and spent 1 1/2 years exploring the Tocantins River. They next ascended the Amazon to Santarém and Óbidos, where they parted to explore separately. Bates went 370 miles farther up the Amazon to Ega, the first important town on the tributary Solimões, remaining there over a year before descending to Belém. For the next 8 years he made collecting trips along the Amazon and its tributaries. His farthest penetration was to Forte Boa (approximately 66°W), from which he wished to go to the Andes, but because of failing health he returned to England in 1859. He took over 14,000 specimens, mostly insects, of which about 8,000 had previously been unknown to science.

Bates reached England with health and financial circumstances both poor. He managed to publish his only book, The Naturalist on the Amazons, in 1863; Darwin contributed the preface. In 1864 Bates became assistant secretary of the Royal Geographical Society, a post he held until his death on Feb. 16, 1892. This relieved him of financial worries, enabled him to support his family, and gave him influence to use in behalf of many explorers, including some in the Africa he never visited. Besides his work for the society, Bates wrote papers for scientific journals and was considered a great authority, perhaps the greatest, on Coleoptera (beetles and weevils).

Bates was responsible for first formalizing the principle of mimicry, though it was further developed later. It is the principle of protective resemblance. Species of animals that are defenseless and edible develop resemblances to species that are injurious and unfit for food, thus gaining some immunity from attack. Animals may also come to resemble plants, though the phenomenon is most generally found among creatures structurally similar.

Further Reading

• Barbara G. Beddall, ed., Wallace and Bates in the Tropics: Introduction to the Theory of Natural Selection (1969), offers excerpts from the writings of the two scientists. J. N. L. Baker, A History of Geographical Discovery and Exploration (1931; 2d ed. 1967), furnishes a concise account of Bates's travels in the Amazon region.
• Moon, Harold Philip, Henry Walter Bates FRS, 1825-1892: explorer, scientist, and Darwinian, Leicester: Leicestershire Museums, Art Galleries, and Records Service, 1976.