Henry Walter Bates FRS FLS FGS (Leicester, 8 February 1825 – London, 16 February 1892) was an English naturalist and explorer who gave the first scientific account of mimicry in animals. He was most famous for his expedition to the Amazon with Alfred Russel Wallace in 1848. Wallace returned in 1852, but lost his collection in a shipwreck. When Bates arrived home in 1859 after a full eleven years, he had sent back over 14,000 species (mostly of insects) of which 8,000 were new to science.[1]
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Bates was born in Leicester and, like Wallace, T.H. Huxley and some other British scientists of the time, he had no formal education in science, and left school at 12. He came from a literate middle-class family and taught himself mainly by reading (like Wallace, Huxley and Herbert Spencer, he was an auto-didact). At 13 he became apprenticed to a hosier. He joined the Mechanics' Institute (which had a library), studied in his spare time, and collected insects in Charnwood Forest. In 1843 he had a short paper on beetles published in the journal Zoologist.[2]
Bates became friends with Wallace when the latter took a teaching post in the Leicester Collegiate School. Wallace was also a keen entomologist, and he had read the same kind of books as Bates had, and as Darwin, Huxley and no doubt many others had. Malthus on population, James Hutton and Lyell on geology, Darwin's Voyage of the Beagle, and above all, the anonymous Vestiges of the Natural History of Creation, which put evolution into everyday discussion amongst literate folk. They also read William H. Edwards on his Amazon expedition,[3] and this started them thinking that a visit the region would be exciting, and might launch their careers.[4]
In 1847 Wallace and Bates discussed the idea of an expedition to the Amazon rainforest, the plan being to cover expenses by sending specimens back to London. There an agent would sell them for a commission. The main purpose was for the travellers to "gather facts towards solving the problem of the origin of species", as Wallace put it in a letter to Bates. The two friends, who were both by now experienced amateur entomologists, met in London to prepare themselves. This they did by viewing South American plants and animals in the main collections.[5] Also they collected 'wants lists' of the desires of museums and collectors. Letters survive in the Kew Garden library of letters from the pair asking what plants the Director (then William Jackson Hooker) would like them to find.
Bates and Wallace sailed from Liverpool in April 1848, arriving in Pará (now Belém) at the end of May. For the first year they settled in a villa near the city, collecting birds and insects. After that they agreed to collect independently, Bates travelling to Cametá on the Tocantins River. He then moved up the Amazon, to Óbidos, Manaus and finally to the Upper Amazon (Solimões). Tefé was his base-camp for four and a half years. His health eventually deteriorated and he returned to England, sending his collection by three different ships to avoid the same fate as Wallace. He spent the next three years writing his account of the trip, The Naturalist on the River Amazons, widely regarded as one of the finest reports of natural history travels.
In 1861 he married Sarah Ann Mason.[6] From 1864 onwards, he worked as Assistant Secretary of the Royal Geographical Society (effectively, he was the Secretary, since the senior post was occupied by a noble figurehead). He sold his personal Lepidoptera collection to Godman and Salvin and began to work mostly on beetles (cerambycids, carabids, and cicindelids). From 1868-9 and 1878 he was President of the Entomological Society of London. In 1871 he was elected a Fellow of the Linnaean Society, and in 1881 he was elected a Fellow of the Royal Society.
He died of bronchitis in 1892 (in modern terms, that may mean emphysema). A large part of his collections are in the Natural History Museum (see The Field, London, February 20, 1892). Specimens he collected went to the Natural History Museum [then called the BM(NH)] and to private collectors; yet Bates still retained a huge reference collection and was often consulted on difficult identifications. This, and the disposal of the collection after his death, are mentioned in Edward Clodd's Memories.[7]
Henry Bates was one of a group of outstanding naturalist-explorers who were supporters of the theory of evolution by natural selection (Charles Darwin and Alfred Russel Wallace 1858).[8] Other members of this group included J.D. Hooker, Fritz Müller, Richard Spruce and Thomas Henry Huxley.
Bates' work on Amazonian butterflies led him to develop the first scientific account of mimicry, especially the kind of mimicry which bears his name: Batesian mimicry.[9] This is the mimicry by a palatable species of an unpalatable or noxious species. A common example seen in temperate gardens is the hover-fly, many of which – though bearing no sting – mimic the warning colouration of hymenoptera (wasps and bees). Such mimicry does not need to be perfect to improve the survival of the palatable species.[10]
Bates noted of the Heliconids (long-wings) that they were forest-dwellers who were:
And yet, said Bates "I never saw the flocks of slow-flying Heliconidae in the woods persecuted by birds or dragonflies... nor when at rest did they appear to be molested by lizards, or predacious flies of the family Asilidae [robber-flies] which were very often seen pouncing on butterflies of other families... In contrast, the Pieridae (sulfur butterflies), to which Leptalis belongs [now called Dismorphia] are much persecuted."
Bates observed that a large number of the Heliconid species are accompanied in the districts they inhabit by other species (Pierids), which counterfeit them, and often cannot be distinguished from them in flight. They fly in the same parts of the forest as the model (Heliconid) and often in company with them. Local races of the model are accompanied by corresponding races or species of the mimic. So a scarce, edible species assumes the appearance of an abundant robust, noxious species. Predators learn to avoid the noxious species, and a degree of protection covers the edible species, no doubt proportional to its degree of likeness to the model. All aspects of this situation can be, and have been, the subject of research. Thus began a field of research which is still quite active today.[11]
Bates, Wallace and Müller believed that Batesian and Müllerian mimicry provided evidence for the action of natural selection, a view which is now standard amongst biologists.[12] Field and experimental work on these ideas continues to this day; the topic connects strongly to speciation, genetics and development.[13]
Bates spent the best part of a year at Ega (now Tefé) in the Upper Amazon (Solimões),[14] where he reports that turtle was eaten regularly, and insect catches were especially abundant. He found upwards of 7,000 species of insects in the area, including 550 distinct species of butterfly.[15] Bates nursed a sick toucan back to health. Tocáno (the Indian name, after its cries) proved to be an intelligent and amusing companion, with a voracious appetite. Mainly a fruit-eater, he learnt the meal-times "to a nicety", and would eat flesh and fish as well as fruit.[16]
There have been many changes in place names, and some in taxonomic names since Bates' time. It is an awkward fact of historical biology that place names, species names and higher classification are apt to change as times passes. A good example is the Galápagos islands, where the government of Ecuador changed even some of the Spanish names, and almost all the islands are now differently named from Darwin's account. Furthermore, Darwin's finches, whatever they may be, are not finches! It is a good idea to keep lists of such name changes as one reads the older texts.
Bates' original work was done on a group of conspicuous butterflies which he knew as the family Heliconiidae.[17] He divided this assemblage into two groups, the Danaoids, having affinities with the great family Danaidae; and Acraeoids related to the Acraeinae. The former are now known as Danainae, the milkweed butterflies, main genus Danaus. The latter are now known as the subfamily Heliconiinae, the long-wings, main genus Heliconius. Both are subfamilies in the Nymphalidae, and both groups tend to feed on poisonous plants. The milkweed plant supplies poisonous glycosides which render both caterpillar and imago Danaids noxious, and the Heliconid caterpillars feed on poisonous Passiflora vines.
Chisholm, Hugh, ed (1911). "Bates, Henry Walter". Encyclopædia Britannica (11th ed.). Cambridge University Press.
"Sketch of Henry Walter Bates". Popular Science Monthly 42. November 1892.