Anth 120 week 4 part 1- Evolution
Anth 120 week 4 part 1- Evolution ANTH 120 001
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This 11 page Class Notes was uploaded by Katie Blackmer on Sunday October 2, 2016. The Class Notes belongs to ANTH 120 001 at George Mason University taught by Nawa Sugiyama in Fall 2016. Since its upload, it has received 11 views. For similar materials see Unearthng Past:Prehistory, Culture Evolution in Anthropology at George Mason University.
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Date Created: 10/02/16
Human Evolution Common Misconceptions: Humans evolved from chimpanzees Humans share a common ancestor with chimpanzees. Chimps are our closest living relative, not a direct ancestor Evolution tree: HOMINID VS HOMINOID Hominid: any member of the family Hominidae, including all australopithecines and the genus Homo Hominoid: any member of the superfamily Hominoidea, including humans, all living apes, and numerous extinct ape and humanlike species from the Miocene, Pliocene, and Pleistocene epochs Hominin: JUST humans’ direct ancestors PLEISTOCENE CLIMATE 1.8 million years ago- Pleistocene climate During one of these fluctuations we start to see a Hominid species evolve Climate change is a backdrop of adaptability FUNDAMENTAL HUMAN ADAPTATIONS Bipedalism: organism moves by means of its two rear limbs or legs. Teeth: What are their diets? How do teeth adapt to conditions around them Brain Maturation: the process of development ANATOMICAL CHANGES IN BIPEDS These include changes in: o The vertebral column, or spine o The skull The pelvis and birth canal o The muscles and bones of the leg o The foot o The arm BIPED & QUADRUPED FORAMEN MAGNUM Spinal cord enters the skull and connects to the brain through an entry (foramen magnum) in the occipital bone. PELVIS & BIRTH CANAL Problem: o Bipedalism requires narrow bony, birth canal but increased intelligence requires bigger skull Adaptations: o Shortened gestation o Rotation in birth canal o Broadened pelvis o Unfused skull in newborn o Birth assistance (social) o Sexual differences in pelvis LEG CHANGES BIPEDAL FOOT Foot is stouter with stronger arches to support greater weight. Arches absorb shock from walking while robust big toe and tarsal bones provide stability BIPEDALISM: A. AFARENSIS Laetoli footprints 30 meter trail in volcanic ash Created when three individuals walked on volcanic ash Showed they had an efficient, bipedal gait, confirming anatomical evidence Created by A. afarensis, or Kenyanthropus platyops? BIPEDALISM TRADEOFFS Advantages: o Increased ability to see long-distance and over grass o Greater ease to transport food and offspring o Ability to run long distance o Frees hands future tool making and use o Energy savings Disadvantages: o More exposure to predators (they see you when you see them) o Standing and walking while carrying can lead to back injury, arthritis, and slipped disks over the long term o Hard on circulatory system to pump to brain and legs (varicose veins) o If foot is injured, cannot travel Dentition Early hominins (Australopithecines) have larger anterior teeth producing greater facial prognathism than genus Homo. Brain Brain size o Bigger and more compressed o requires a lot of energy to maintain bigger brain o Diet needs to maintain bigger brain First use of fire First evidence of control over fire is associated with H. ergaster/erectus. WHEN DID H. ERGASTER/ERECTUS FIRST USE FIRE? Controversial early evidence o 1.5-1.6 mya E.g. Koobi Fora (Kenya) baked earth near stone tools o 1.6 mya 400-800 kya sites in Europe & Asia show burned bones & traces of hearths MATURATION Low birth rate Adolescent developmental period Brain development Social complexity Longevity Ardipithecus group The earliest humans are our closest link to other primates. They evolved in Africa and took the first steps towards walking uprigh. Sahelanthropus tchadensis Name Means: Sahel ape-man from Chad Nickname: “Toumai” When Found: 2001 Who Found: M. Brunet Lived When: sometime between 7-6 Ma Lived Where: Chad, western Africa Fossil Record: 1 skull, some jaw & tooth fragments Basic Morphology: apelike: small brain, sloping face, very prominent brow ridges, and elongated skull; humanlike: small canine teeth, a short middle part of the face, and a spinal cord opening beneath the skull instead of towards the back Australopithecus group Species in this group of early humans walked upright on a regular basis, but they still climbed trees, too. Australopithecus afarensis Name Means: southern ape of the Afar Nickname: “Lucy” When Found: 1930s/1974 Who Found: Don Johanson’s team Lived When: about 3.85‐2.95 Ma Lived Where: Ethiopia, Kenya, Tanzania How Big? ~ chimpanzee; strong sexual dimorphism Fossil Record: >300 individuals, including many juveniles! Basic Morphology: mosaic ‐‐ ape like: face proportions (a flat nose, a strongly projecting lower jaw) , small braincase and long, strong arms with curved fingers; more humanlike small canine teeth,pelvis ,leg bones Known For: One of longest‐lived, best‐ known early human species; “Lucy” & “First Family” (Hadar); Laetoli footprints; Dikika child Paranthropus group Large teeth and powerful jaws enabled this group of early humans to feed on a variety of foods Paranthropus boisei Name Means: Zinj for the medieval East African region of Zanj; boisei for Charles Boise, the team’s funder Nickname: “Zinjanthropus”, “Nutcracker Man” When Found: 1955 / 1959 Who Found: Mary Leakey Lived When: about 2.3 – 1.2 Ma Lived Where: eastern Africa (Ethiopia, Kenya, Tanzania, Malawi) Size: (avg) males: 5 ft 4 in, 108 lbs; females: 4 ft 1 in, 75 lbs Fossil Record: some nearly complete skulls, some postcrania Basic Morphology: big sagittal crest; huge cheek teeth with very thick enamel; flaring cheekbones Known For: big teeth, sagittal crests, strong chewing muscles, co-existed with H. habilis, H. erectus and H. rudolfensis in east Africa Homo group Like modern humans, other species in this group had large brains and used tools. Members of this group were the first to expand beyond Africa Homo habilis Name Means: handy man Nickname: none When Found: 1960 Who Found: Louis & Mary Leakey Lived When: about 2.4‐1.4 Ma Lived Where: eastern and southern Africa How Big? 3 ft 4 in – 4 ft 5 in; 70 lbs Fossil Record: many fairly complete skulls, partial skeleton, others Basic Morphology: slightly larger braincase and smaller face and teeth than Australopithecus; modern arch of the foot; some ape‐like features, including long arms and a moderately prognathic face Known For: oldest toolmaker & meat‐ eater; put East Africa on the human evolution map Homo erectus Name Means: upright walking man Nickname: “Turkana Boy”, ‘Peking Man”, “Java Man” When Found: 1891 Who Found: E. Dubois “Pithecanthropus erectus” (Trinil 2) Lived When: about 1.89 Ma – 70,000 Ya Lived Where: Northern, Eastern, and Southern Africa; Western Asia (Dmanisi, Rep ublic of Georgia); East Asia (China and Indonesia) How Big? 4 ft 9 in – 6 ft 1 in; 88‐150 lbs Fossil Record: many fairly complete skulls, partial skeletons Basic Morphology: human‐ like body size and shape with longer legs and shorter arms Known For: longest lived species on our family tree; first out of Africa; modern bod y size and shape; Acheulean handaxes; increased meat‐ eating; first evidence of caring for old, weak individuals EARLY HOMO Origins of Homo: ~2.3 Mya ago o First found: in Tanzania, Africa by Richard Leakey o Larger brains Smaller teeth Australopithecus limb proportions o Rapid development STONE TOOLS? PROBLEMS: • Olduvai tools found at same level as Homo habilis, but P. boisei cannot be ruled out • Earliest direct evidence from Gona (Ethiopia) dating back to 2.6 and 2.5 mya • Earliest indirect evidence for stone tools (3.39 mya) found in area of A. afarensis. • Australopiths first tool makers? Define homo group Stone tools have also been used by previous hominoid groups BIG BRAINS? Problems: o Homo habilis had cranial capacity as small as 510 cc (KNM-ER 1813) BRAIN SIZE COMPARISON Pan troglodytes (chimpanzee): 400 cc Australopithecus africanus: 450 cc Homo habilis: 612 cc Homo ergaster/erectus: 500-1000 cc Homo sapiens: 1350 cc DEFINING GENUS HOMO Reduced post-orbital constriction Reduced lower facial prognathism More anteriorly situated foramen magnum Narrower tooth crowns, particularly in the lower premolars Reduction in length of the molar tooth row, thin enamel More parabolic dental arcade TRAITS OF EARLY HOMO Large(ish) brains Small teeth, thin enamel, parabolic dental arcade Rounded skulls, small, less prognathic face, reduced jaw musculature Homo neanderthalensis Name Means: “tal” – a modern form of “thal” = valley (Feldhofer Cave, Neander Valley, Germany) Nickname: “Neanderthal Man” When Found: 1829 , 1848, named in 1864 Who Found: quarry workers ‐> local teacher Fuhlrott ‐> anatomist Schaaffhausen Lived When: about 200,000 – 28,000 Ya Lived Where: Europe; southwestern to central Asia How Big? (avg) males: 5 ft 5 in, 143 lbs; females: 5 ft 1 in, 119 lbs Fossil Record: many nearly complete skulls and skeletons Basic Morphology: low forehead; brow ridges; big nose; big brains; large middle face; a ngled cheek bones; short, muscular bodies Known For: Our closest extinct cousins; made sophisticated tools (Mouseterian); skilled large game hunters (including marine shellfish & mammals); made loose‐ fitting clothing; occasionally made symbolic/ornamental objects; burial (ritual?) Homo sapiens Name Means: Latin: “wise man” or “knowing man” Nickname: “Cro‐Magnon Man” When Found: 1868 / no true type specimen Who Found: (workmen) Lived When: about 200,000 Ya ‐ present Lived Where: evolved in Africa, now worldwide How Big? varies across time and space Fossil Record: excellent! Basic Morphology: lighter skeletons that earlier humans; thin‐ walled, high‐ vaulted skull with flat and near vertical forehead; virtually no brow ridges; lightly built j aws with smaller teeth Known For: Worldwide distribution with huge population size, very large brains, using tools to make other tools/technological advancements, agriculture and domestication, civ ilization/cities, low genetic diversity Unique Behaviors: fishing; bows and arrows; long distance trade and social networks; v aried diet; language, writing, art, music, personal adornment, rituals; abstract reasoning; self‐ awareness; long growth & development (only species to have grandparents), …
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