Born of British missionary parents, Leakey spent his youth with the Kikuyu people of Kenya, about whom he later wrote. He was educated at the University of Cambridge and began his archaeological research in East Africa in 1924; he was later aided by his second wife, the archaeologist Mary Douglas Leakey (née Nicol), and their sons. He held various appointments at major British and American universities and was curator of the Coryndon Memorial Museum in Nairobi from 1945 to 1961.
In 1931 Leakey began his research at Olduvai Gorge in Tanzania, which became the site of his most famous discoveries. The first finds were animal fossils and crude stone tools, but in 1959 Mary Leakey uncovered a fossil hominin (member of the human lineage) that was given the name Zinjanthropus (now generally regarded as a form of Paranthropus, similar to Australopithecus) and was believed to be about 1.7 million years old.
Leakey later theorized that Zinjanthropus was not a direct ancestor of modern man; he claimed this distinction for other hominin fossil remains that his team discovered at Olduvai Gorge in 1960–63 and that Leakey named Homo habilis.
Leakey held that H. habilis lived contemporaneously with Australopithecus in East Africa and represented a more advanced hominin on the direct evolutionary line to H. sapiens. Initially many scientists disputed Leakey’s interpretations and classifications of the fossils he had found, although they accepted the significance of the finds themselves. They contended that H. habilis was not sufficiently different from Australopithecus to justify a separate classification. Subsequent finds by the Leakey family and others, however, established that H. habilis does indeed represent an evolutionary step between the australopiths (who eventually became extinct) and H. erectus, who may have been a direct ancestor of modern man.
Among the other important finds made by Leakey’s team was the discovery in 1948 at Rusinga Island in Lake Victoria, Kenya, of the remains of Proconsul africanus, a common ancestor of both humans and apes that lived about 25 million years ago. At Fort Ternan (east of Lake Victoria) in 1962, Leakey’s team discovered the remains of Kenyapithecus, another link between apes and early man that lived about 14 million years ago.
Leakey’s discoveries formed the basis for the most important subsequent research into the earliest origins of human life. He was also instrumental in persuading Jane Goodall, Dian Fossey, and Biruté M.F. Galdikas to undertake their pioneering long-term studies of chimpanzees, gorillas, and orangutans in those animals’ natural habitats. The Louis Leakey Memorial Institute for African Prehistory in Nairobi was founded by his son Richard Leakey as a fossil repository and postgraduate study centre and laboratory.
According to Britannica.com