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29 Cards in this Set
- Front
- Back
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Olduvai Gorge |
"cradle of humankind" in East Africa Mary and Louis Leakey found the remains - Why Olduvai? there was evidence of humans, tools, animal carcasses |
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What is a Hominin? |
Morphological characteristics shared by living humans and their ancestors, but not by apes. - best understood from obligate behaviours: 1. Bipedal locomotion 2. Non-honing chewing |
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Bipedalism |
Scientists thought brain size was catalyst for evolution; wrong. Bipedalism actually predated most attributes by millions of years. |
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7 characteristics associated with bipedalism |
1.Foramen Magnum: positioned at bottom of skull 2.Shape of the Spine: S-shape in humans, c-shape in apes; for stability. 3.Shape of the pelvis: short front to back 4. length of legs: long, relative to the body and arms. 5.Valgus Knee: Angled inward 6.Longitudinal Arch: supports weight and balance, increased leverage during movement. 7.Big Toe: not opposable. |
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Costs of Bipedalism |
Costs: -visibility to predators -back injury -foot injury -circulatory strain |
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Benefits of Bipedalism |
Benefits: -visibility -transportation ease -run long distances -hands are free |
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Non Honing Chewing |
Hominins: - small blunt non-projecting canines - wear on tip of canine, no sharpening, premolar cusps are smaller - vertical crushing , thick enamel *in humans the temporalis muscle is vertically oriented. |
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Hominins Evolution |
Most hypotheses focus on bipedalism as the reason for evolution. emergence in late Miocene epoch (10-5.3 mya) |
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Hunting Hypothesis by Darwin |
Life in the trees to life on the ground that lead to specific changes 4 differentiating characteristics: - humans are bipedal - non honing canines - tool use - big brains freed hands for carrying weapons for hunting - crucial later but not with hominins. |
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Patchy Forest Hypothesis by Rodman and McHenry |
Evolved due to efficiency of being on 2 legs instead of 4 in certain habitats, arose when forest was becoming patchy at beginning of Miocene. - dispersal of food, more energy efficient when having hands free. |
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Provisioning Hypothesis by Owen Lovejoy |
Freeing of hands lead to bipedalism -extended infant care, meant mother could only care for 1 child at a time. - male provisioning meant more kids, while monogamy ensured food, protection, and need free hands to complete these tasks. |
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Pre-Australopithecines |
7-4 mya -Had a number of primitive attributes -more ape-like, than human in some characteristics -1st recognizable ancestors that are part of human lineage |
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Sahelanthropus tchadensis |
7-6 mya - earlist pre-australo - found 2500km west of Rift Valley (Chad); where all other early hominins in east africa were found. -cranial capacity tied to human-ness (350cc) - bran primitive like an ape -massive brow ridges - bipedal (FM pos) and non honing canine |
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Orrorin Tugenensis |
6 mya -Femoral neck length suggested bipedalism - finger bones curved like apes - dentition similar to Sahelanthropus (non-honing) |
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Ardipithecus Kadabba |
5.8-5.5 mya (Ethiopia) - Canines wore at tips, but did have some honing * perihoning complex, primitive trait that was intermediate between apes and modern humans. |
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Ardipithecus ramidus |
4.4 mya 1. Fossil numbers: at least 35 individuals, most complete early hominin skeleton 2.Species snapshot: behaviour and adaptation, lived in forest landscape 3.Characteristics: short, non-projecting canines, enamel thickness between apes and humans, opposable toes, but musculature rigid, curved fingers, adapted to tree and ground. Primitive but still in lineage of humans. |
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Australopithecines |
4-1 mya -9 species from 1 genus -variation mostly in size and robusticity -general characteristics: small brains and canines, large molars and premolars -later were robust |
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Australopithecus anamensis |
4 mya - oldest species, found in east Africa - similar to ardipithecus, likely ancestral - characteristics: large canines, parallel dentition, premolar cusps |
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Australopithecus afarensis |
3.6-3 mya - four main sites (Tanzania (Laetoli), Ethiopia (hadar,kasi dora, dikika)) - 430 cc - hyoid ape-like, no speech - large canines -prognathism of lower face. - similarities with anamensis but not as primitive: parabolic dentition, canines are smaller, varied tooth wear. |
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Lucy |
Australopithecus afarensis - 3.2 mya -1974 Hadar - 40% of the skeleton - 3.5 feet tall - bipedal - curved fingers (some arboreal locomotion) |
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Australopithecus (Kenyanthropus) platyops |
3.5 mya - lesser known, contemporary with A.afarensis - Kenya - face unusually flat - small brain 400-500cc - split of the Australopithecine lineage |
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Australopithecus Garhi |
2.5 mya - link between A.afarensis and early homo - large teeth, premolar cusps almost equal in size -small brain 450cc arm to leg ratio more human-like - tool production and use (Oldowan complex 2.6-1.6 mya) - flexor muscle in thumb |
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East African Australopithecines |
Robust and extinct before 1 mya - A. aethiopicus - A. boisei |
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Australopithecus aethiopicus |
2.5 mya - small brain 410cc - large jaw and molars - sagittal crest - flaring cheekbones |
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Australoepithecus boisei |
2.3-1.2 mya -small brain 510cc -hyper robust -thick enamel - highly specialized for heavy chewing |
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South African Australopithecines |
2 gracile and 1 robust - extinct by 1 mya - lineage leading to Homo - A. africanus - A. robustus - A. sediba |
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A. africanus |
3-2 mya - larger teeth than A. afarensis - small brain 450cc - fingers not curved - arm to leg ratio ape-like -rapid maturation |
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A. robustus |
2 -1.5 mya - longest surviving lineage in South Africa - large premolars and molars - large face, 530cc - well developed sagittal crest |
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A. sediba |
2 -1.8mya - face, jaw, and teeth are small - small brain 420cc - fingers not curved - long arms - may be related to early homo |
