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Order Primates: Monkeys, apes, humans, lemurs, tarsiers, and
related animals.
Primate characteristics, mostly related to arboreal adaptations (life in the trees):
Vision in depth (stereoscoptic vision) requires eyes rotated in front so that the visual fields of right and left eyes overlap. In a horse or rabbit, the eyes are off to each side, giving a wider panoramic view of danger coming from any direction but much less depth information because of minimal overlap between the right and left visual fields (and, if you look face-to-face with a horse, you're looking up their long snout). Primates have their eyes in front for better depth perception: if you jump to the next branch, you need to know exactly how far away it is, or else you may fall down some 20 stories from a tropical tree. Look at the illustration of any primate (like Teilhardina in the lab handout), and you're looking at them eye-to-eye! "Visual inspection" behavior means picking up objects and bringing them up close for better viewing (in 3 dimensions) and turning them around (again, a 3-D perception). This leads to an increase in learning and intelligence, but at a price: there is so much to learn, and therefore a long time (childhood) needs to be spent under parental care because all the skills of adulthood have not been learned yet. More intense parental care (which includes carrying infants through the treetops) limits the number of offspring to one at a time (usually, with selection against twins— they are at greater risk for prematurity and other problems). This results in a single uterus in primates (while most female mammals have paired uteri and multiple births); and female primates also have fewer nipples. Plesiadapoidea or Paromomyiformes: Extinct, archaic primates. Lemuroidea or Strepsirhini: Lemurs, lorises, and galagos.
Tarsioidea: Tarsius and its extinct relatives. Platyrrhina: New World monkeys and marmosets, with 3 premolars in each jaw, flat noses, and strong tails that aid in locomotion. Catarrhina: Old World monkeys, apes (gibbons, orangutan, gorilla, chimpanzee) and humans, with 2 premolars in each jaw, protruding noses (nostrils opening downward), and reduced tails, native to Africa, Asia, and Europe. Family Hominidae (humans): Catarrhine primates distinguished from apes (fam. Pongidae) principally by upright locomotion. Characteristics include: Origin of Hominidae: Approximately 5-6 million years ago when upright posture was attained. Human footprints at Laetoli, Tanzania, are 4.1 million years old. Evolutionary "dead ends": A number of hominid fossils are now considered to be evolutionary "dead ends," not ancestral to modern humans. These include Sahelanthropus, Ororrin, Kenyapithecus, Ardipithecus, and the large or "robust" Australopithecus robustus and A. boisei. Australopithecus: The best-known early hominids, from South Africa and East Africa. Certain early species (Australopithecus anamensis, A. afarensis) may have been ancestral to Homo, but later species were not. One nearly complete skeleton of A. afarensis, nicknamed "Lucy," was only about 4 feet tall and walked upright. Homo habilis: An East African contemporary of Australopithecus, from about 4 to 1.5 million years ago. Body size about 4 feet tall. Perhaps responsible for early stone tools. Homo erectus: Lived in the middle Pleistocene, after the extinction of Australopithecus. Fossils known from Europe, Africa, Asia. In Zhoukoudian cave near Beijing, China, heat-fractured rocks show that fire was used. (This is the oldest evidence of the use of fire, about 600,000 years ago.) Homo sapiens: First appeared in the late part of the Ice Age. Taller skull than earlier species. Used more advanced tools. Invented agriculture around 8,000 years ago. |
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