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Chapter 5

Anthropology - Chapter Five - Humans and the Environment.docx

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Karen Slonim

CHAPTER FIVE – HUMANS AND THE ENVIRONMENT Hominids  Bipedalism: ability to walk upright on two legs  Separates from other primates  Identifies as distinct family  Closest fossil relatives of modern humans  Australopithecus: 6 million – 1 million years ago  Genus Homo: appeared 2 million years ago  Evolved from Australopithecus  Had larger brain size  Started with Homo habilis and then Homo erectus Trends in Hominid Evolution  All hominids are bipedal  Prolonged infant dependency  Manual dexterity  Generalized skeleton  Distinctive features: reduction of face, jaw, teeth, larger brain size  Loss of body hair  Developed different skin colours  Cannot find certain things out from fossil remains Bipedalism  Hominids are only primates that are fully bipedal  Hips and knee bones are different for this  Foramen magnum is at bottom of the skull for humans  Foramen magnum at back of skull for animals  Why Bipedalism? o Probably evolved as a result of may factors not just one o Thermoregulation is best explanation for bipedalism o Had social and behavioural consequences o Freed up hands so could use tools, transport food, carry babies Origins of Bipedalism Tool Use  Freed hands to make tools  Tools would give access to greater variety of food sources  Increasing survival and reproductive success  Existing evidence does not support this  Earliest tools were way after bipedalism  Capability of tool making is not dependent on bipedalism  Nonhuman primates can also make tools Transport of Food and Offspring  Not proven hypothesis either  Offspring could cling firmly to mother on all fours  Mother could move freely to find food or safety  Bipedalism would allow infant to be carried  No longer able to move quickly through trees though  Would not help in avoiding predators so would not adapt to this Provisioning  Combination of activities and interactions contributed to bipedalism  Could transport food back to mate by walking upright  Provisioning by male allowed female to spend more time with child  Parental attention would promote survival of infants  This reproductive strategy favoured sexual fidelity  No fossil evidence of this Thermoregulation Models  Early human fossils found in hot areas (Central Africa)  Less heat generated in bipedal legs  Easier to move around to get food  Less body hair and sweat glands would also provide adaptive advantage  Could move around for food in heat of day when predators had to rest  Slower than four legged animals over short distances  Moved more efficiently over long distances  Able to travel longer distances to search for food  Fossils cannot provide records of body hair and sweat glands  Hard to find evidence of this model as well Reduction of the Face, Teeth and Jaws  Oldest hominids have: o Protruding face o Jaw extends further than humans o Larger canine teeth, gaps between teeth of opposing jaw to accommodate o Teeth arranged in U-shaped pattern o Teeth on opposite sides of mouth are parallel  Teeth/cranial structure that suggests diet: o Robust australopithecines have huge chewing muscles and big molars show a diet of coarse vegetation o Homo species had more varied diet cause had smaller molars and less big chewing muscles Increase in Cranial Capacity  Defining characteristics of genus Homo is increased cranial capacity and complexity of brain  Increase in relative and absolute size  Hominid brain more than doubled in last 2 million years  Influenced social and physical developments  Prompted modifications in diet, use of tools, evolution of language, social organization  All of these areas may have improved survival of early hominids Fossil Evidence for Hominid Evolution The Oldest Hominids  Bipedalism happened 6-10 million years ago  Discovered Sahelanthropus tchadensis which is oldest hominid  Teeth and cranium are mixture of ape and hominid  Teeth are smaller than apes and do not extend below other teeth  Shape and orientation of head suggests more four-legged movement  Ardipithecus ramidus: o More widely accepted as “oldest hominids” o Fossils found in Ethiopia o Primitive when compared to later austrlopithecines o Cranial capacity was fairly small o Cranium more apelike o Canine teeth are larger o Was bipedal Early Hominids from Kanapoi and East Turkana  Australopithecus anamensis: o 3.9-4.2 million years ago o Legs show they were bipedal o Skull and teeth are priminve o External ear opening different than recent hominids o Transitional link between Ardipithecus and australopithecines Australopithecus afarensis  Found by Donald Johanson and Maurice Taieb  3-4 million years ago  Some of earliest well-described hominid remains  Fossils are primitive when compared to later australopithecines  Upper body is curved so was well adapted for climbing and moving through environments with trees  Lower limb bones, pelvic orientation, position of hips and knees indicate it was bipedal  Lucy: o Fossilized skeleton that was almost 40% in tact o Small cranium and large canine teeth o Skull resembles modern chimpanzee o Spine, pelvis, hips, thigh bones, feet show she was bipedal  The Dikika Baby: o Took five years to extract cause encased in stone o Fossil of a three-year-old child o Almost complete skull, entire torso, most of legs, parts of arms o Bipedal and well suited for arboreal environment o Arm sockets are more like a gorilla than human The Laetoli Footprints  Thousands of footprints of various species of ancient animals preserved in layer of mud covered with volcanic ash  Found by Mary Leaky  Confirms fully bipedal creatures roamed earth 3.5 million years ago  Trail is 75ft long made by two hominids Australopithecus africanus  Has smaller cranial capacity than more recent genus Homo  Taung child round by Raymond Dart  Unique characteristics of “Taung child”: o Foramen magnum was further forward than most modern apes o Head as balance above spine o Moved with upright posture of biped o Brain was very small o Structure was more developed than apes in some reasons o Teeth were closer in size to human than to ape  Other A. africanus Finds: o Other fossil finds that were like Taung child o Discoveries established Taung child as hominid and Australopithecus as valid genus Branches on the Family Tree  Some fossil finds reveal creatures unlike humans  Species classified as robust australopithecines  Wer also bipedal  Dated 2.7-1 million years ago  Prove that multiple species of hominid roamed Africa at same time  Robust Australopithecines from South Africa: o Large, broad face o Enormous teeth and jaws o Placed in genus Paranthropus o 1-2 million years ago o Big chewing muscles meant relied heavily on diet of tough foods  Australopithecus boisei: The “Nutcracker Man” o Found in East Africa o Teeth were larger than any other australopithecine o Could be dated at 1.75 million years old o Easy to date because of layers of volcanic ash found in  The “Black Skull”: o Found stained by blue-black manganese in the soil o Initially classified as Australopithecus boisei o Had some features resembling older australopithecines o Designated to be Paranthropus aethiopicus o 2.5 million years old o Cranium is small o Face is large and robust, has massive teeth The Origins of Genus Homo  First two species were Homo habilis and Homo rudolfenis  Different from australopithecines because of large cranial capacity  2.2 million-1-6million years ago  First discovered by Leakeys  Main feature was large brain capacity  Homo rudolfenis has flatter/broader face with thickly enameled cheek teeth Homo erectus  1.8 million-400,000 years ago  Widest distribution of any hominid  Share many similarities wit modern humans  Oldest remains found in Africa  “Turkana boy”: o Found in Kenya o Mostly complete skeleton of 8-year-old boy o Comparable with size of humans today o Human from the neck down o Smaller brain capacity than modern humans  Java Man: o Homo erectus has been found in Asia o Discovered by Eugene Dubois o Cranium was small an
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