Alfred Russel Wallace: one of the greatest biologists in history
The British naturalist Alfred Russel Wallace (1823-1913) became famous for his discoveries on his journey through the Malay Archipelago. Here, he discovered the Wallace Line, developed his idea of evolutionary theory and subsequently wrote his most important literary work.
Who was Alfred Russel Wallace?
Alfred Russel Wallace was a 19th-century British explorer, naturalist and geographer fascinated by new and contrasting species. Born in 1823 in the Welsh town of Usk (now in Monmouthshire), his family later moved to England. Growing older, Wallace developed a passionate devotion to nature and a scepticism towards religion. The travelling scientist began questioning the predominant theory of creation at the time, representing the concept of a god-like being creating evolution. 1837 Wallace started an apprenticeship in his brother’s surveying office, to significantly improve his skills as a mapmaker.
Where did Alfred Russel Wallace go on his first voyage?
Alfred Russel Wallace’s first voyage was to Brazil. 1848, he explored the Amazon River Basin with a friend, the naturalist Henry Walter Bates, to examine the region’s exotic fauna and learn more about the evolutionary mechanisms that produced and shaped it. To finance the trip, they collected specimens and sold them.
One of Wallace’s most exciting discoveries in the Amazon was identifying two different species of tamarind monkey. One was brown and white and lived only on the river’s north bank. While the other was black and lived only on the river’s south bank. This finding led Wallace to ask whether a geographical boundary caused the two species to evolve differently. The discovery also laid the foundation for his later research on Indonesian animal species and the foundations of evolutionary biogeography.
Alfred Wallace collected thousands of specimens of insects, birds, and other animals. He spent four years in Brazil before deciding to sail back to Britain in 1852 due to illness. Unfortunately, the ship he was sailing on caught fire, in the middle of the open sea - taking his entire collection with it. He was able to rescue himself, with most of his notes and his impressively accurate map of the Rio Negro in the Amazon onto a lifeboat, where he stayed for ten days before being rescued.
The Malay Archipelago excursion
1854, Wallace began his 8-year-long travels through the Malay Archipelago (now Malaysia and Indonesia). This journey was blessed with even greater success than his trip to South America. He accumulated an astonishing number of specimens.
What is the Wallace Line?
While studying the distribution of animals around the archipelago, Wallace noticed an abrupt switch in fauna. He concluded that there was a boundary line that divided the region in two. Later, this line, which runs south between the Indonesian islands of Bali and Lombok and north between Borneo and Sulawesi, became known as the Wallace Line. It marks the frontier separating living organisms with an evolutionary connection to either Asia or Australasia. This line was drawn in 1859 and became particularly clear when focusing on the differences in mammals between the two regions. Wallace’s idea was stunningly in line with nowadays knowledge.
What is the significance of the Wallace Line?
The water depth along the Wallace Line is significantly deeper than that between the Asian- and Australian-like islands. During the Ice Age, this fact caused the Wallace Line to remain unfrozen and to continue to be a consistent dividing line. Wallace believed that the other shallower waters around the islands had frozen during the Ice Age, connecting the islands to each other and their respective mainland. This connection would have allowed the animals to migrate to the surrounding areas. However, except for animals that can fly or swim, the Wallace line has kept the ecosystems separate.
Alfred Russel Wallace’s contribution to the evolution theory
On the island of Ternate (now in Indonesia) in 1858, had a realisation that influenced Charles Darwin’s theory of evolution. What Wallace came to realise was how species evolved. Only the fittest individuals survived and could reproduce, passing on their beneficial traits to their offspring.
Wallace immediately passed on his idea to Darwin, who had already worked on this theory for 20 years. Darwin then published his masterpiece “The Origin of Species” in 1859 and became famous for the theory of evolution by natural selection alone - overshadowing Wallace.
Wallace’s most successful piece of literature
Wallace returned to England in 1862. Four years later, he married Annie Mitten. Together they had three children.
Back home, Wallace published a narrative of travel, The Malay Archipelago. His vivid descriptions of the unknown islands, including detailed records of birds of paradise, orangutans and encounters with the locals, opened up a whole new world to readers.
"The great contrast between the two divisions of the Archipelago is nowhere so abruptly exhibited as on passing from the island of Bali to that of Lombok, where the two regions are in closest proximity … The strait is here fifteen miles wide, so that we may pass in two hours from one great division of the earth to another, differing as essentially in their animal life as Europe does from America."
- Excerpt from The Malay Archipelago by Alfred Russel Wallace
At the age of 90, Alfred Russel Wallace died at his country home, Old Orchard, on 7 November 1913.
Follow the footsteps of the great Alfred Russel Wallace
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