Lecture 7: Early Hominin
Lecture 7: Early Hominin 101
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This 7 page Class Notes was uploaded by JaCene T. on Friday October 9, 2015. The Class Notes belongs to 101 at University of New Mexico taught by Tanya Muller in Fall 2015. Since its upload, it has received 15 views. For similar materials see Intro to Anthropology in anthropology, evolution, sphr at University of New Mexico.
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Date Created: 10/09/15
Lecture 7 Early Hominins What Makes Us Human 393 Bipedalism O 90 O 90 O 90 Upright twolegged locomotion differentiates early hominins from apes Energetic efficiency Adaptation to open grasslandsavanna habitat 393 Provides ability to see over long grass for food and predators and to carry items back to a home base 393 Exposes less body surface to solar radiation which facilitates cooling and reduces moisture loss Hair over our bodies serves its purpose the hair on our heads protect our brains from the heat and radiation from the sun 393 Adaptation likely predated this however 393 Brains Skulls and Childhood Dependencygoes hand in hand Brain size and skull size increased especially with advent of Homo even before homo Brain increased when homos left to the Savanna Why Dietary changes The Savanna provided more resources Large brains are correlated with longer life spans Human children have long period of childhood dependency due to larger skulls and brains Humans can t birth babies with full grown brains Coevolution species evolving together Text notes that first evidence for hominin stone tool manufacture dates to 26 million years ago in terms of actual tool remains Evidence of intentional cutting of bones indicative of the use of stone tools as early as 34 million years ago with stone tools now dating back to 33 million year ago Bipedal locomotion allowed early hominins to carry things Chimpanzees can indicate if a tool rock will later be useful for cracking nuts Thought to be unique to humans however it has been proven primates use tools as well as other species including dolphins Advantageous for early hominins to have large back teeth and thick tooth enamel because of savanna diet of fibrous gritty vegetation like sandpaper Hominins jaws get bigger and teeth get bigger 393 Rotary motion circle of chewing vegetation also favored reduction of canines and first premolars 393 Lost during subsequent human evolution further reduction with advent of fire Cooking breaks down cells and proteins making meat softer and easier to chew Fire is a very important aspect of human culture We alter the environment just as much as the environment alters us 393 Larger teeth mean larger skulls Chronology of Hominin Evolution 0 Hominin designates human line after split from ancestral chimps 0 Hominid taxonomic family that includes humans and the African apes and their immediate ancestor 393 Anatomically modern humans Homo sapiens sapiens populated the new world 0 Although first hominins appeared late in the Miocene epoch the Pliocene 52 million years ago Pleistocene 2 million years ago 10000 BP and recent 10000 BP present epochs are the most important 0 Humans are creating the next biggest extinction We may be driving the extinction of ourselves 0 If earth s history 24 hours 393 Midnight Earth originates 393 545 am earliest fossils deposited 0 902 pm first vertebrates appeared 0 1045 pm earliest mammals 0 1143 pm earliest primates 393 1157 pm earliest hominins 393 36 seconds before 1200 am Homo sapiens The Earliest Hominins 393 Toumai Sahelanthropus tchadensis 393 6 to 7 millionyearold primate skull Northern Chad 393 May be the earliest hominin found 393 Human and apelike characteristics chimp sized brain hominin like tooth enamel thicker than chimps 393 Probably moved bipedally foramen magnum 393 Indicates that hominin evolution was not confined to East Africa s Rift Valley 393 Orrorin tugenensis 393 Pieces of jaw with teeth isolated upper and lower teeth arm bones and fingers 393 Possible early hominin Kenya 393 Dated to 6 million years ago 393 Anatomical features suggest Orrorin climbed trees easily still has long fingers and walk on two legs bipedalism 393 Ardipithecus 0 Ardipithecus kadabba 58 55 million years ago v Ardipithecus ramidus Nicknamed Ardi 44 million years ago nearly complete skeleton found in 2009 0 PelVis transitional between arboreal climbing and bipedal locomotion feet lack arch of later hominins 0 Lived in a humid woodland site 0 Plausible ancestor for Australopithecus The Varied Australopithecines 393 Major hominin group of the Pliocene 393 At least six species 393 A anamensis 42 to 39 million years ago 393 A afarensis 38 to 30 million years ago 393 A africanus 30 to 20 million years ago 0 90 A garhi 25 million years ago 393 A robustus 20 to 10 million years ago 0 90 A boisei 26 to 10 million years ago 393 A anamensis 393 Bipedal hominin northern Kenya Maeve Leakey and Alan Walker in 1995 393 Fossils from two sites date to 42 million years ago Kanapoi and to 39 million years ago Allia Bay 393 Molars have thick enamel and large apelike canines 393 Weighed about 110 pounds O 90 May be ancestral to A afarensis but larger than either Ardipithecus or later Australopithecus afarensis 393 A afarensis Fossils from Laetoli Tanzania 3836 million years ago and Hadar Ethiopia 3330 million years ago Suggest hominins common ancestry with the African apes is recent no more than 8 million years ago Certain features of dentition are similar to those of apes sharp canines Evidence of powerful chewing diet included tough vegetation Lucy s Baby 393 33 million year old fossilized toddler uncovered in North Ethiopia 0 Remarkable for its age and completeness 0 No prolonged dependent childhood v Walked upright but hints that ancestors had not completely left trees 0 As recently as 3 million years ago our ancestors had a mix of apelike and hominin features Cranial capacity smaller than later hominins Fossilized footprints at Laetoli 36 million years ago and structure of postcranial features indicate that A afarensis was bipedal Marked sexual dimorphism Structurally more robust than modern humans arms longer than legs climbed trees Narrower birth canal period of dependency may provide indirect evidence for rudimentary cultural life 393 Gracile and robust australopithecines O 90 O 90 Gracile A africanus and robust sometimes called Paranthropus robustus lived in South Africa between 3 and 1 million years ago 393 Probably descended from A afarensis 393 Hyperrobust group existed in East Africa 393 Some scholars separate species A boisei others regional variant of A robustus 393 The Varied Australopithecines Competing models of relationship 393 Separate species graciles ancestral to robusts 393 Separate species overlapping in time 393 Represent continuum of variation in a single polytypic species 0 Sexually dimorphic Extreme sexually dimorphic in the robust species 0 Teeth jaw face and skull indicate diet increasingly focused on coarse vegetation Emergence of meat eating Originally scavengers and weren t very good at it there was a lot of competition with other scavengers such as Hyenas and African Dogs We were not always on top of the food chain 0 Overall robustness especially in the chewing apparatus increased through time 0 Cranial capacity only increased slightly Australopitahecines and Early Homo 393 Split between Australopithecus and Homo occurred before 2 million years ago 393 Fossil sample of hominin teeth evidence of split 393 Smaller set H habilis 0 Larger set A boisei coexisted with Homo until around 10 million years ago 0 Occupied different ecological niches by 19 million years go Homos are characterized by the dependency of meat and culture 393 Split between Australopithecus and Homo 393 J ohanson and White propose that between 3 and 2 million years ago A afarensis split into two groups 393 H habilis evolved into H erectus by 17 million years ago v Various australopithecines A africanus A robustus and A boisei 0 Fossil evidence that Homo and A boisei coexisted in East Africa 0 H erectus which appears to have lived contemporaneously with H habilis between 3 and 2 million years ago 0 Relatively recent A sediba 195178 million years ago presents mosaic of primitive and modern features 0 Oldowan Tools 393 Oldowan pebble tools 2520 million years ago 393 Core and ake tools around 18 million years ago at Olduvai Gorge Tanzania more akes than cores 393 Core choppers for pounding akes for cutting 393 Older stone implements 252 million years ago found in Ethiopia Congo Malawi 393 Debate over identity of the earliest stone tool makers Oldowan Tools 2520 million years ago 393 Core and ake tools around 18 million years ago at Olduvai Gorge Tanzania more akes than core 393 Core choppers for pounding akes for cutting 393 Older stone implements 252 million years ago found in Ethiopia 393 A garhi and early stone tools 393 Fossils from a gracile hominin species A garhi dating to 26 million years ago Found in Ethiopia in 1999 393 Associated with remains of butchered animals 393 Stone tools also dating to 26 million years ago found at nearby site suggest that Australopithecines were toolmakers with some capacity for culture Earlier stone tools 393 2009 Dikika Ethiopia 34 million year old bone fragments with both tooth marks and cut marks Old evidence tools were used to eat meat 393 This is the earliest evidence of meat and marrow consumption by hominins 393 No tools were found at that site so it was unclear whether the marks were made with handmade tools or just naturally sharp rocks 393 2011 artifacts found next to Lake Turkana almost by accident 393 By the end of the 2012 field season excavations at the site named Lomekwi 3 had uncovered 149 quotLomekwianquot stone artifacts More complex First time anyone found a more primitive tool 393 It remains unknown what species made these stone tools Australopithecus Kenyanthropus or unknown species 393 Kenyanthropus a 33millionyearold skull of which was discovered in 1999 about a halfmile from the newfound tools Lomekwian tools 393 The techniques to make them may represent a stage between the pounding used by earlier hominins and the knapping of later toolmakers Knapping is knocking to rocks together 393 Climate likely shrubby woodland 393 Lomekwian stone tools may have been used for breaking open nuts or tubers bashing open dead logs to get at insects inside or maybe something not yet thought of instead of scavenged kills of grasslands Chimpanzee are developing stone tools right now Anthropology Today 393 Anthropologist s Son Finds New Species of Australopithecus 393 9 year old Matthew Berger when chasing his dog into high grass tripped over a log and stumbled onto the bones of a new hominid species that lived almost 2 million years ago 393 Ancient remains of a 4 foot 2 inch just a few years older than Matthew 393 Fossils as a surprising and distinctive mixture of primitive and advanced anatomy and thus earned new species distinction Australopithecus sediba 0 Human lower body apelike arms small teeth and more modern face of Homo but primitive feet of Australopithecus 0 Most likely lived 178195 million years ago probably descended from A africanus Debate as to which genus it belongs in Summag O 9 Know the four key human attributes identified by Kottak and be able to discuss their significance for hominin evolution Know the chronology of hominin evolution Be able to identify the oldest known bipeds their approximate dates of existence and their connection to australopithecines and to Homo Be able to identify and distinguish among the six species of Australopithecus discussed in the chapter Know the differences between gracile and robust australopithecines as well as the explanations posited for their evolutionary relationship and their connection to early Homo Understand what distinguishes Homo from the australopithecines Know the sequence for the earliest stone tools What kind of tools were made When did they first appear Who made them
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