Louis Seymour Bazett Leakey was born on August 7, 1903, in Kabete, Kenya. His parents, Mary Bazett (d. 1948) and Harry Leakey (1868-1940) were Church of England missionaries at the Church Missionary Society, Kabete, Kenya. As a child, while pursuing his interest in ornithology--the study of birds--he often found stone tools washed out of the soil by the heavy rains, which Leakey believed were of prehistoric origin. Stone tools were primary evidence of the presence of humans at a particular site, as toolmaking was believed at the time to be practiced only by humans and was, along with an erect posture, one of the chief characteristics used to differentiate humans from nonhumans. Scientists at the time, however, did not consider East Africa a likely site for finding evidence of early humans; the discovery of Pithecanthropus in Java in 1894 (the so-called Java Man, now considered to be an example of Homo erectus) had led scientists to assume that Asia was the continent from which human forms had spread.
Shortly after the end of World War I, Leakey was sent to a public school in Weymouth, England, and later attended St. John's College, Cambridge. Suffering from severe headaches resulting from a sports injury, he took a year off from his studies and joined a fossil-hunting expedition to Tanganyika (now Tanzania). This experience, combined with his studies in anthropology at Cambridge (culminating in a degree in 1926), led Leakey to devote his time to the search for the origins of humanity, which he believed would be found in Africa. Leakey's next expedition was to northwest Kenya, near Lakes Nakuru and Naivasha, where he uncovered materials from the Late Stone Age; at Kariandusi he discovered a 200,000-year-old hand ax.
In 1928 Leakey married Henrietta Wilfrida Avern, with whom he had two children: Priscilla and Colin; the couple was divorced in the mid-1930s. In 1931 Leakey made his first trip to Olduvai Gorge--a 350-mile ravine in Tanzania--the site that was to be his richest source of human remains. Leakey's first discoveries at that site consisted of both animal fossils, important in the attempts to date the particular stratum (or layer of earth) in which they were found, and, significantly, flint tools. These tools, dated to approximately one million years ago, were conclusive evidence of the presence of hominids--a family of erect primate mammals that use only two feet for locomotion--in Africa at that early date.
In 1932, near Lake Victoria, Leakey found remains of Homo sapiens(modern man), the so-called Kanjera skulls (dated to 100,000 years ago) and Kanam jaw (dated to 500,000 years ago); Leakey's claims for the antiquity of this jaw made it a controversial find among other paleontologists.
In the mid-1930s, a short time after his divorce from Wilfrida, Leakey married his second wife, Mary Douglas Nicol; she was to make some of the most significant discoveries of Leakey's team's research. The couple eventually had three children: Philip, Jonathan, and Richard E. Leakey Richard E. Leakey. During the 1930s, Leakey also became interested in the study of the Paleolithic period in Britain, both regarding human remains and geology, and he and Mary Leakey carried out excavations at Clacton in southeast England.
Until the end of the 1930s, Leakey concentrated on the discovery of stone tools as evidence of human habitation; after this period he devoted more time to the unearthing of human and prehuman fossils. His expeditions to Rusinga Island, at the mouth of the Kavirondo Gulf in Kenya, during the 1930s and early 1940s produced a large number of finds, especially of remains of Miocene apes. One of these apes, which Leakey named Proconsul africanus, had a jaw lacking in the so-called simian shelf that normally characterized the jaws of apes; this was evidence that Proconsul represented a stage in the progression from ancient apes to humans. In 1948 Mary Leakey found a nearly complete Proconsul skull, the first fossil ape skull ever unearthed.
During the late 1950s, the Leakeys continued their work at Olduvai. In 1959, while Louis was recuperating from an illness, Mary Leakey found substantial fragments of a hominid skull that resembled the robust australopithecines--African hominids possessing small brains and near-human dentition--found in South Africa earlier in the century. Louis Leakey suggested that this represented a new genus, which he named Zinjanthropus boisei, the genus name meaning "East African man," and the species name commemorating Charles Boise, one of Leakey's benefactors. This species, now called Australopithecus boisei, was later believed by Leakey to have been an evolutionary dead end, existing contemporaneously with Homo rather than representing an earlier developmental stage.
In 1961, at Fort Ternan, Leakey's team located fragments of a jaw that Leakey believed were from a hitherto unknown genus and species of ape, one he designated as Kenyapithecus wickeri, and which he believed was a link between ancient apes and humans, dating from fourteen million years ago; it therefore represented the earliest hominid. In 1967, however, an older skull, one that had been found two decades earlier on Rusinga Island and which Leakey had originally given the name Ramapithecus africanus, was found to have hominid-like lower dentition; he renamed it Kenyapithecus africanus.Leakey's theories about the place of these Lower Miocene fossil apes in human evolution have been among his most widely disputed.
During the early 1960s, a member of Leakey's team found fragments of the hand, foot, and leg bones of two individuals, in a site near where Zinjanthropus had been found, but in a slightly lower and, apparently, slightly older layer. These bones appeared to be of a creature more like modern humans than Zinjanthropus, possibly a species of Homo that lived at approximately the same time, with a larger brain and the ability to walk fully upright. As a result of the newly developed potassium-argon dating method, it was discovered that the bed from which these bones had come was 1.75 million years old. The bones were, apparently, the evidence for which Leakey had been searching for years: skeletal remains of Homo from the Lower Pleistocene. Leakey designated the creature whose remains these were as Homo habilis ("man with ability"), a creature who walked upright and had dentition resembling that of modern humans, hands capable of toolmaking, and a large cranial capacity. Leakey saw this hominid as a direct ancestor of Homo erectus and modern humans.
A request came in 1964 from the Israeli government for assistance with the technical as well as the fundraising aspects involved in the excavation of an early Pleistocene site at Ubeidiya. This produced evidence of human habitation dating back 700,000 years, the earliest such find outside Africa.
During the 1960s, others, including Mary Leakey and the Leakeys' son Richard, made significant finds in East Africa; Leakey turned his attention to determining when humans had reached the North American continent. Concentrating his investigation in the Calico Hills in the Mojave Desert, California, he sought evidence in the form of stone tools of the presence of early humans, as he had done in East Africa. The discovery of some pieces of chalcedony (translucent quartz) that resembled manufactured tools in sediment dated from 50,000 to 100,000 years old stirred an immediate controversy; at that time, scientists believed that humans had settled in North America approximately 20,000 years ago. Many archaeologists, including Mary Leakey, criticized Leakey's California methodology--and his interpretations of the finds--as scientifically unsound. Human remains were not found in conjunction with the supposed stone tools, and many scientists have not accepted these "artifacts" as anything other than rocks.
Shortly before Louis Leakey's death, Richard Leakey showed his father a skull he had recently found near Lake Rudolf (now Lake Turkana) in Kenya. This skull, removed from a deposit dated to 2.9 million years ago, had a cranial capacity of approximately 800 cubic centimeters, putting it within the range of Homo and apparently vindicating Leakey's long-held belief in the extreme antiquity of that genus; it also appeared to substantiate Leakey's interpretation of the Kanam jaw. Leakey died of a heart attack in early October, 1972, in London.
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