When the young Yorkshire botanist Richard Spruce first saw the Amazon in 1849, he wrote excitedly to a friend: 'The largest river in the world flows through the largest forest. Fancy if you can two millions of square miles of forest [Spruce's italics] uninterrupted save by the streams that traverse it!'
Spruce was right: the Amazon is far and away the world's largest river by most criteria. Of all the water that enters the oceans from all the rivers on Earth, one fifth flows through the Amazon--that's more than the next five largest rivers combined. It's also the colossus in the size of its basin, number and size of tributaries, and probably even in length (whether the Amazon or the Nile is the longest river has been a matter of debate for many years). And, as Spruce surmised, this great river also winds through the largest mass of tropical rainforest (roughly 60 per cent of the world's total), and this forest contains the richest biodiversity of any ecosystem.
So why was Britain not more concerned with the mighty Amazon? Perhaps it was because the British Empire's only foothold near the river was British Guiana (now Guyana), so the Nile and Central Asia were of far greater strategic interest. British engineers and businessmen were active throughout South America during the 19th century, but explorers and scientists tended to leave it to their counterparts from the USA. And, the Amazon was first navigated by Francisco de Orellana's Spanish explorers in 1542, whereas the rivers of Central Africa were still tantalisingly unknown to Europeans three centuries later.
There were, however, some notable exceptions to this disregard, and the Royal Geographical Society was involved with most of them. In 1835, five years after the Society was founded, its council received an impressive map from a young German by the name of Robert Schomburgk. The Society engaged Schomburgk to explore the interior of British Guiana, which he did with some success.
In 1838-39, Schomburgk embarked on an extraordinary circuit: starting from Fort Sao Joaquim in the extreme north of Brazil, he persuaded Indians to paddle him up scores of rapids of the unexplored Uraricoera river, across an unknown watershed to the upper Orinoco in Venezuela, through the Casiquiare link, down the Negro and back up the Branco. He had said that he would return to the fort in a year; in fact, the 3,500-kilometre journey only took him seven months. It's a feat that would deserve one of the Society's gold medals today; Schomburgk received his in 1840.
In 1848, two young Englishmen, 23-year-old Henry Walter Bates and 25-year-old Alfred Russel Wallace, arrived at the mouth of the Amazon. Bates had left school at 12 and Wallace when only slightly older; neither had any money or family influence. They met at Leicester Collegiate School as fellow insect collectors and shared a passion for natural history.
After reading a contemporary travel book about the Amazon, Bates and Wallace decided to explore the region 'to gather facts towards solving the problem of the origin of species'. They rapidly organised an agent to sell specimens they collected in order to defray the cost of their voyage and departed for South America; the botanist Spruce joined them a year later.
Bates, Wallace and Spruce were together for some time, before travelling up and down the Amazon and its great tributaries, sometimes in pairs but mostly alone. They were never out of the forest and rivers, collecting feverishly, exploring uncharted territory, making first-class scientific discoveries, and surviving hazards such as near-drowning, getting lost, attempted robberies, agonising bites, hunger and violent attacks of malaria. Despite these hardships, Wallace researched in Amazonia for four years, Bates for 11 and Spruce for 16.
Bates observed that some edible insects survive predation by imitating the gaudy colouring of poisonous species--a strategy now known as Batesian mimicry. …