Transcript Hominids - Los Gatos High School
Hominid Species
Australopithecus afarensis –
died.
A (4)
Estimated age: 3.2 million years Date of discovery: 1974 Location: Hadar, Ethiopia Lucy was 3 feet 6 inches tall, 62 pounds, and 25 years old when she About 40% of her skeleton was found and her leg bones showed her to have been bipedal. Low forehead, a face that projected far forward and a very prominent brow ridge. Earliest species for which we have reliable brain and body size estimates The brain was about 1/3 the size of the average modern human brain, or about the same size as a modern ape's brain. Males also typically had large crests on top of their skulls A. afarensis probably inhabited the savannas and open woodlands where they likely found fruits, seeds, and roots.
Laetoli Footprint Species:
A. afarensis
Age: 3.6 million years Date of Discovery:1974 1975 Location: Laetoli, Tanzania Discovered by:Mary Leakey
It is possible to tell that the gait of these early humans was "heel-strike" (the heel of the foot hit first) followed by "toe-off" (the toes push off at the end of the stride); the way modern humans walk. Thus, bipedality was essentially developed by this time.
http://www.pbs.org/wgbh/evolution/library/07/1/l_071_ 03.html
3.25 mya, a volcanic eruption left a blanket of ash. Rain turned the ash to cement preserving footprints At least two individuals were present, walking along side each other. This demonstrates incontrovertibly that 3.6 million years ago, early humans were bipedal (walking upright on two legs). Their big toes hardly diverged from the rest of the foot, this can be seen in the photograph at the top right of the imprint. In comparison, a chimpanzee has a highly diverged big toe, and is able to use it like a thumb.
Australopithecus africanus
Estimated age: 3 to 2 million years
– E (3)
Date of discovery: 1924 Location: Taung, South Africa Like A. afarensis, A. africanus also showed marked differences in size between males and females. Although the teeth and jaws of A. africanus were much larger than modern human teeth, they are still more similar to ours than to the teeth of apes. The upper and lower jaws of A. africanus were also fully rounded in front, like those of modern humans, and their canine teeth were smaller on average than those of A. afarensis.
Australopithecus africanus
individuals probably inhabited open woodlands, where they would have foraged for fruits, seeds, and roots.
Homo habilis – D (1)
Estimated age: 2.0 million years Date of discovery: 1960 Location: Olduvai Gorge, Tanzania Some scientists believe that many of the earliest fossils assigned to H. habilis are too fragmented and separated in time for conclusions about their relationships or species compositions to be possible. Homo habilis, "handy man," is so called because of the wealth of tools that have been found with its fossils. The average H. habilis brain was considerably larger than the average Australopithecus brain. The brain shape is also more humanlike. The bulge of Broca's area, essential for speech, is visible in one H. habilis brain cast, indicating that the species may have been capable of rudimentary speech. The average H. habilis individual is thought to have been about five feet tall and 100 pounds
Australopithecus boisei * (6)
Estimated age: 1.8 my Date of discovery: 1959 Location: Olduvai Gorge, Tanzania Australopithecus boisei is similar in body and brain size to A. robustus. Like members of many other Australopithecus species, males and females of A. boisei showed marked differences in size. Some features of A. boisei's skull, including the large grinding teeth, are even larger than are those of A. robustus. A. boisei probably inhabited mixed woodland and savanna habitats, where individuals would most likely have eaten foods like nuts and roots.
Homo erectus – B (2)
Estimated age: 1.7 my Date of discovery: 1999 Location: Republic of Georgia
Homo erectus, unlike H. habilis and all of the Australopithecus species, ranged far beyond Africa. Generally, H. erectus is characterized by large molars, an unpronounced chin, heavy brow ridges, and a long, low skull, relative to modern Homo sapiens. The skeleton of H. erectus was heavier, or "more robust," than the average modern human skeleton. "Turkana Boy" was tall and slender, like modern humans from the same area, while the few limb bones found of "Peking Man" indicate a shorter, sturdier build.
Homo (sapiens) neanderthalensis – C (5)
Estimated age: 70,000 - 40,000 years Date of discovery: 1953 - 1960 Location: Shanidar Cave, Iraq Protruding jaw, receding forehead, and weak chin. The Neanderthal brain was slightly larger than that of modern humans, but this is correlated with larger body size The mid-facial area of Neanderthals protruded much more than the same area in H. erectus or H. sapiens and may have been an adaptation to cold. Neanderthal bones are thick and heavy and show signs of powerful muscle attachments. They are found throughout Europe and the Middle East.
Homo sapiens
Estimated age: 100,000 to 90,000 years Location: Qafzeh Cave, Israel The modern form of Homo sapiens first appeared about 100,000 years ago. This species is distinguished by large brain size, a forehead that rises sharply, eyebrow ridges that are very small, a prominent chin, and lighter bone structure Even in those 100,000 years, anatomical trends toward smaller molars and decreased bone mass can be seen in the Homo sapiens fossil record.
Pan troglodytes - F Chimpanzee Not a hominid
Homo floresiensis
("Man of Flores") is a species in the genus Homo , remarkable for its small body, small brain, and survival until relatively recent times. It is thought to have been contemporaneous with modern humans ( journal Homo sapiens except for arm bones Nature ) on the remote Indonesian island of Flores. One sub-fossil skeleton, dated at 18,000 years old, is largely complete Also here, parts of six other individuals, all diminutive, have been recovered as well as similarly small stone tools from horizons ranging from 94,000 to 13,000 years ago. Flores has been described (in the ) as "a kind of Lost World", where archaic animals, elsewhere long extinct, had evolved into giant and dwarf forms through allopatric speciation. (speciation by geographical isolation)