A Science Odyssey Human Evolution

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drawing of Ardipithecus ramidus Ardipithecus ramidus
The most primitive hominid yet found, this species has more chimpanzee-like features than any other human ancestor. Ardipithecus ramidus may have walked upright. Other fossils discovered with A. ramidus suggest that the species lived in the forest.
4.4 mya
first fossils found 1992

drawing of Australopithecus anamensisAustralopithecus anamensis
Exhibiting some chimp-like characteristics, A. anamensis' jaws are more primitive than those of later hominids. And yet, its humerus (an arm bone) is quite human-like. Characteristics of its tibia (a lower leg bone) indicate that A. anamensis walked on two feet.
4.2 - 3.9 mya
first fossil found 1965

drawing of Australopithecus afarensis Australopithecus afarensis
This species includes "Lucy," the 3.2 million year old fossil found by Donald Johanson. A. afarensis' small braincases and relatively large teeth and chewing muscles are similar to those of chimpanzees. However, their teeth, as well as their leg and pelvis bones, exhibit human-like characteristics. They ranged in height from three and a half feet to five feet and walked upright.
3.5 - 2.9 mya
first fossils found 1973

drawing of Australopithecus africanus Australopithecus africanus
Although similar in many ways to A. afarensis, this species had a slightly larger brain (but still only slightly larger than a chimp's brain), smaller canine teeth, and larger molars. The wear of the teeth suggests that A. africanus ate fruits and foliage.
3.0 - 2.4 mya
first fossils found 1924

drawing of Australopithecus robustus Australopithecus robustus
Believed to be roughly the same size as A. afarensis, A. robustus had a large, "robust" (heavier, thicker) skull, as well as a jaw and large teeth that were well adapted to chewing. Like some present-day apes, this species had a "sagittal crest" (a ridge running from front to back on the top of the skull) from which muscles running to the jaw were attached.
2.1 - 1.6 mya
first fossil found 1938

drawing of Australopithecus boisei Australopithecus boisei
A. boisei is similar to A. robustus, except that its skull and teeth are even larger. Some experts consider the two closely related, both branching from another species called A. aethiopicus. Others believe A. robustus evolved from A. africanus. Like all of the other Autralopithecus species, A. boisei walked upright.
2.3 - 1.1 mya
first fossil found 1959

drawing of Homo habilis Homo habilis
Homo habilis, which actually means "handy man," is apparently the first species to make and use primitive stone tools. About five feet tall and weighing 100 pounds, H. habilis had a brain that was larger than the largest Autralopithecus brain, but smaller than the Homo erectus brain.
2.4 - 1.5 mya
first fossil found 1960

drawing of Homo erectus Homo erectus
The first example of Homo erectus, known as "Java Man," was discovered in Indonesia in 1893. Fossil remains of Homo erectus have since been found throughout Africa and Asia, making it the first wide-ranging hominid. Despite the primitive appearance of its skull, the erectus skeleton is very similar to that of modern humans, although more robust (thicker and heavier). Homo erectus was probably the first hominid to use fire.
1.8 mya - 300,000 years ago
first fossil found in 1893

drawing of Homo sapiens (archaic) Homo sapiens (archaic)
Also known as Homo heidelbergensis, this species has a brain that was larger than H. erectus' and smaller than that of a modern human. The brain was enclosed in a skull that was more rounded than H. erectus'. Fossil remains of archaic Homo sapiens have been found in Africa and Europe.
500,000 - 200,000 years ago
first fossil found in 1921

drawing of Homo sapiens neanderthalensis Homo sapiens neanderthalensis
Averaging five and a half feet in height and possessing short limbs, Neanderthals were well-adapted to living in a cold climate. Attached to their robust (thick and heavy) bones were powerful muscles. The Neanderthal's brain was larger than the brain of living humans, although its shape was longer from front to back and not as rounded in the front.
230,000 - 30,000 years ago
first fossil found in 1856

drawing of Homo sapiens (modern) Homo sapiens (modern)
Modern Homo sapiens, also known as Homo sapiens sapiens, have been around for the past 120,000 years. Homo sapiens living about 40,000 years ago made elaborate tools out of bone, antler, ivory, stone, and wood, and produced fine artwork in the form of carvings and cave paintings.
120,000 years ago - present
first "Cro-Magnon" specimens found in 1868

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