Bio Anth Final Study Guide
Bio Anth Final Study Guide Anth 1001
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This 10 page Study Guide was uploaded by Jaimee Kidd on Thursday April 28, 2016. The Study Guide belongs to Anth 1001 at George Washington University taught by Shannon C. McFarlin in Spring 2016. Since its upload, it has received 28 views. For similar materials see Biological Anthropology in anthropology, evolution, sphr at George Washington University.
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Date Created: 04/28/16
When and Where? • Miocene: Age of apes & earliest human ancestors • Fossils come primarily from East and Central Africa—The Great Rift Valley o 3 continental plates (Indian, Arabian, and African) o Very active volcanic areas à created a stream of lakes down the East African Rift Valley à important for early hominins for vegetation and congregation § Chronometric dating possible because of volcanoes What Makes a Hominin? • Bipedalism • Characteristics of the dentition • Elaboration of material culture • Significant increase in brain size • Long developmental period and long lifespan Origin of Bipedalism • (1) Social Factors o Ability to provision for the family in the context of evolution of monogamous systems, tied to the assumption that early hominins resided in open savanna like environments • (2) Ecological Factors o Moving across forested patches with high energy efficiency, finding food and spotting predators Evidence of Bipedalism • Sahelanthropus tchadensis (7-6mya) o Biped? Position of foramen magnum more directly under the skull o Primitive aspects? Brain size, U-shaped dental arcade o Smaller canines, no CP-3 honing system • Orrorin tugenensis (Kenya, 6mya) o Femoral morphology is indicative of bipedal locomotion o Dental morphology is ape like (large canines) • Ardipithecus ramidus & Ar. Kadabba (Ethiopia 4-6mya) o Biped? Forwardly placed foramen magnum, pelvis has mosaic characteristics for both bipedalism and climbing (short and broad ilium) o Relatively small brain, prognathous, loss of CP-3 honing & reduced canine size, minimal sexual dimorphism • * before australopithecines, several taxa based on very fragmentary and incomplete remains w/ their hominid status debated Australopithecines • Major Trends o Cranial capacity increased marginally o Sloping foreheads o Prominent brow ridges o Prognathous o Adaptations for bipedalism o Larger cheek teeth, reduced canine size, thicker enamel • A. anamensis (Kenya, 4.2-3.9 mya) o Derived traits compared to apes: reduced canines, larger molars, thick enamel, undisputed evidence of bipedalism (enlarged proximal end of the tibia) o Primitive traits: U-shaped dental arcade • A. afarensis (East Africa, 3.9-2.9 mya) o “Lucy” o Face: Sagittal Crest, Strong nuchal crest for neck muscle attachments, small brain size relative to face size, prognathous o Dentition: Canine further reduced, posterior tooth rows near-paralleled, thicker molar enamel, slightly larger cheek teeth o Body: Lumbar Curvature, Foramen Magnum forward facing, short, broad pelvis, enlarged heel, non-opposable big toe, short toes, valgus knee o * also had arboreal features because of its mosaic habitat • A. africanus (South Africa, 3.5-2mya) o “Taung child” o Slightly enlarged brain & rounder cranial capacity o Less prognathous o Less developed nuchal cresting o Reduced anterior dentition o Cheek bones swept forward, nasal pillars o Robust mandible o Larger cheek teeth with thicker enamel • A. sediba (South Africa 2 mya) o Similarities with Australopiths: small brain size, molar morphology, small body size, long upper limbs o Similarities with Homo: projecting nose, smaller teeth and chewing muscles, longer legs, hand with precision grip Major Evolutionary Trends @ 2.5 Mya • Significant cooling & expansion of open grasslands • Australopithecus Splits off to Homo and Paranthopus o à Homo § Increase in brain size and capacity for tool making § Decrease in prognathism and postcanine tooth size § Increase in body size o à Paranthropus § Hyper Masticatory complex § Increase in cheek tooth size § Body size similar to Australopithecus • Paranthropus o Robust Australopithecine o Characterized mainly by dental traits that would’ve allowed them to have a large biting forces § Enlarged sagittal crest shifted more towards the front of the cranium § Flared zygomatic bones § Strong postorbital construction § Robustly built mandibles § Enlarged cheek teeth, thick enamel, front dental reduction and crowding o P. aethiopicus (East Africa, 2.7-2.5 mya) § Well developed sagittal and nuchal crests § “dish-shaped” face § Relatively small brain § Forward projecting cheek bones o P. boisei (East Africa, 2.3-1.2 mya) § Forward-projecting cheek bones § Forwardly placed sagittal crest § Reduced prognathism § Anterior dental crowding: marked reduction in incisors and canines § Thick enamel § Enlargement of premolars and canines; post canine megadonty Early Homo • Trends: o Larger cranial capacity o Slight reduction in size of cheek teeth; more parabolic dental arcade; thinner enamel o Reduced prognathism, more gracile cranium o But, similar in body size to australopithecines o Associated with stone tools • H. rudolfensis (2.4-1.6 mya) o Absolutely larger brain size o Australopith like broad midface o Relatively larger molar teeth o Well-developed mandible for chewing muscles • H. habilis (2.4-1.4 mya) o Absolutely smaller brain size o Broader upper-face than midface o Smaller molars o Less robust mandible o More australopith-like limb proportions • H. naledi (South Africa, Age Unknown) o Homo Features- § Similar in body size to modern humans § Humanesque skull- the general shape of the skull is advanced, thought the brain case is significantly smaller § Versatile hands- palms, wrists, and thumbs suggest tool use § Long legs § Humanlike feet o Australopithecus features § Primitive shoulders- positioned in a way that would have helped with climbing and hanging § Flared pelvis § Curved fingers for climbing in trees Oldowan Tool Industry • Early Stone Age/Lower Paleolithic; 2.6-200 Ka • Cores: lumps of stone from which pieces are removed • Flakes: small fragments removed from cores • Hammerstones: rounded stone used to remove the flakes • What were they used for? o Access the carcasses of animals to obtain meat* o Break bones to obtain marrow* o Plant processing, woodworking Acheulean Tool Industry • 1.6 mya-200,000ya • More sophisticatedà symmetrical, biface tools with retouching and soft hammer percussion • 3 classes of core tools: (1) handaxes (2) cleavers (3) picks o Handaxes have very regular proportions and standardized forms that hold for Africa, Near East, Europe à require more complex cognitive abilities, mental representation of a target image, advanced palnning o Handaxes used for processing large animal carcasses, wood and other plants, non utilitarian purposes Fire • Importance: o Cooking- food becomes more digestible, less food is needed to get the same amount of nutrients, toxins can be neutralized o Warmth- cold and seasonal environments out of Africa, crucial to allow migration o Cave Occupation o Predator Protection o Hunting- part of complex hunting strategies, used together with stone tools/spears o Social functions- facilitated the formation of social bonds, different types of communication • Most Conclusive Evidence of Fire: Gesher Benot Ya’Aqov, Israel: charcoal, burned flints, hearths, also spatially localized suggesting it was contained Pleistocene (1.8 Mya- 10 Ka) • Colder and more variable climate with intervals marked by repeated glacial cycles exposing land bridges connecting continents Homo erectus/ergaster • Reduction in size of cheek teeth • Increased body size and modern human-like limb proportions; long range bipedalism adaptations • Absolute brain size increased • Evidence of fire • Wide geographic distribution outside of Africa, persisted for a long time • Tool use- associated with both stone industries, movius line separates populations that developed acheulean tools and those that didn’t Out of Africa by 1.8 Mya • Big question: Why Now? o Tools and increase cognitive capabilities allows early hominins to colonize new environments? o Obligate long-range bipedalism? o Running after large game? o Fire gives the ability to move into colder climates? o Homo ergaster/erectus trends? Homo floresiensis • Australopith-like brain size, but more vertical profile to the face • Short, about 3.5 ft tall, why? o Insular dwarfism: reduction in size of large animals on island à thus reduction of size since less resources are needed • Australopith-like wrists • Short lower limbs • Flat feet; curved toes • Tools? o Simple flake stone tools (similar to Oldowan), evidence of butchery and hunting, evidence of fire Middle Pleistocene Hominins: “Archaics” (800-150,000 years ago) • Primitive traits (similar to H. erectus) o Long, low skull; thick cranial bones o Very large brow ridges o No canine fossa o No chin o Postcranial skeleton more robust than modern humans • Derived (similar to modern H. sapiens) o Larger cranial capacity o Higher forehead o Arched, double brow ridges o Molar size decreased Human Evolution Sites o (1) Sima del Elefante (1.3 mya, Homo sp., first Europeans) § Oldowan artifacts, hominin remains, species assignment is not clear o (2) Gran Dolina (850-950 ka Homo antecessor) § Oldowan tools, cutmarks on human bones as evidence of cannibalism, human bones processed in the same way as other fauna • Homo antecessor- o Initially described as the last common ancestor of Neanderthals and modern humans o Facial traits similar to H. sapiens o Dental traits similar to Neanderthals o Possible dead evolutionary end; evolutionary relationships are unclear o (3) Sima de los Huesos (400 ka, Homo heidelbergensis) § Clear relationship with Neanderthals § Carnivores and humans; at least 28 individuals § Causes of the accumulation are unclear, intentional? • H. heidelbergensis- o Large number of specimens in Europe o Direct ancestors of Neanderthals Middle Stone Age/Middle Paleolithic Tool Industry • Mousterian- prepared core technology o Middle Pleistocene hominins and Neanderthals o Required even more planning than Acheulean tools o The Levallois Technique o Evidence of big game hunting- bones of large animals, may have stampeded large animals over the edge of cliffs, collaborative hunting effort Upper Pleistocene Hominins: Neanderthals (H. neanderthalensis) • 150-27 ka • More robust facial structure in general o Inflated cheeks, as opposed to canine fossa in humans o Occipital bun o Retromolar space o Larger jaws, larger teeth o Double-arched brow ridges o Large nose o Prognathism • Robust, heavily muscled body o Barrel-shaped rib cage o Thick leg bones o More muscular and stocky figure à adaptation to different climates and ecological conditions (colder environment than humans) • Dentition o Use of the mouth as a “third hand” à extremely worn • Tools o Mousterian (Mode 3): prepared core technology, associated with tools that are specifically made out of flint stone which fractures very easily in order to create thin, sharp tools, *evidence that tools were found locally so they did not transport raw material long distances as humans did o Later Stone Age/Upper Paleolithic—Aurignacian (Mode 4) § Blade Based technology suggest that Neanderthals were capable of creating more complicated tools, more prevalent with the coming of modern humans • Behavior o Hafted weapons, competent hunting o Interpersonal violence, cannibalism o Long-term survival of sick or injured individuals o Use of pigments o Burial without grave goods o Little evidence of long-distance networks • Interactions o Neanderthals & Modern Humans co-inhabited in Europe for approximately 10,000 years § Both species hybridized (DNA analyses) o Related to extinction? § Direct competition, ecological competition, genetic replacement… Denisovans • Siberia, 40 kya, little known about their anatomy • Sister group to Neanderthals, hybridized with modern humans o Complex relationships w/ Neanderthals and modern humans o Europeans and Asian populations (not African) carry 1-4% Neanderthal DNA • What impact did inbreeding have on us today? o Areas of our genome with Neanderthal DNA: § Keratin, Kin color, risk factors for certain diseases (Chron’s disease, lupus, type 2 diabetes) o Areas that lack Neanderthal DNA- § Activated in the testes § Located in the Y chromosome Models for Anatomically Modern Homo Sapiens • Multiregional Model o Pleistocene hominins represent a single evolving lineage across different regions o AMHS evolved in the context of significant gene flow between regions • Out of Africa Model o AMHS originated in Africa and later dispersed to occupy the Old World o No gene flow/interbreeding, but replacement of existing hominins • Assimilation Model o Genetic data are most consistent with assimilation (or partial replacement): o African origin of modern humans: § Greatest amount of genetic diversity in Africa, AMHS first appear in the fossil record of Africa o But varying degrees of interbreeding with populations they found as they migrated AMHS • Behavioral Innovations-Evidence from Archaeology o Behavioral modernity wasn’t association with abrupt change, no single cognitive “explosion” that led to the modern human mindà Gradual Acquisition o Some important innovations- § Projectile technology § Fishing § Personal adornment, larger social networks, exchange networks, as evidenced by beads • Importance of projectiles—more success, less risk, survivorship increases, competitive advantage § Belief systems? (burial with grave goods) • Ritual Burial o Upper Paleolithic graves commonly included artifacts, body adornments, and sprinklings of red ochre • Art o Intensification and consistent presence of: music, rock art, portable art, including figurines o Rock art- variety of scenes, including animal figures, often rather realistically drawn, human figures were less common, abstract patterns o • Music o Expression and comprehension of social and emotional information o Flutes made from animal bones • Expanded Subsistence Base o More varied diet, which also included use of aquatic resources • Settlement Patterns o Sites occupied for longer periods and extensively modified, evidence of more permanent shelters • Modern Human Advantages o Innovative- new, more elaborate technologies, projectile weapons, clothing, shelters, and other innovations in material culture o Cognitive- personal adornments and symbolic behavior, art and music, ritual o Social- larger social networks, exchange networks, buffered risk of starvation Evolution of the Brain and Language • Human brains are especially big • Human brains are highly encephalized o As body weight increases, brain size increases in a pretty regularly way, however, human brains are roughly 3 times the expected size for an anthropoid of our size o Encephalization: the proportional size of the brain relative to body size • Humans do not have the largest brains in comparison with extant or fossil species • Human brains are highly gyrified o Gyrification index: the degree of folding of the cortex § Increases with brain size o Effective brain size can increase without an associated increase of the skull • Anatomy- § Brainstem: Regulates many basic body functions § Cerebellum: Integrates sensory perception, coordination & motor control; learning new motor skills § Cerebrum (Neocortex): Higher cognitive functions, such as sensory perception, generation of motor/action commands, spatial reasoning, memory, conscious thought, speech, language § Lobes: • Frontal Lobe: Many higher cognitive functions associated with intelligence • Parietal Lobe: Integrates sensory information from different modalities, important for tool using • Temporal Lobe: Primary auditory cortex, visual object recognition, processing of semantics, long-term memory • Occipital Lobe: Primary visual cortex Evolution of the Human Life Cycle • Compared to other mammals of similar size, primates develop slowly and invest heavily in offspring. ◦ Primates have: ▪ Long gestation lengths ▪ Large neonates ▪ Low reproductive rates (i.e. they reproduce infrequently) ▪ Long developmental periods and late ages at maturity ▪ Long lifespans ▪ Large brains • Primate Life Stages ◦ Prenatal Period ▪ Conception to Birth ▪ Susceptibility to teratogens ◦ Infancy ▪ Begins at birth ▪ Dependent on mother for nutrition & protection (lactation) ▪ Ends with weaning & eruption of first permanent tooth ◦ Juvenile ▪ Travel and forage independently ▪ Learn important social skills ▪ Ends with sexual maturation ◦ Adulthood ▪ Reproductively mature ▪ Begins at eruption of last permanent tooth • Distinctive Features of the Human Life Cycle ◦ Childhood ▪ Between infancy & juvenile period ▪ Occurs after weaning, when children are still dependent on others for food ▪ Period of learning technical and social skills, language ▪ Ends with the attainment of adult brain size ◦ Adolescence ▪ Between juvenile and adulthood ▪ Begins with the onset of sexual maturity ▪ Allows for an extended period of social learning, and continued brain maturation ▪ Marked acceleration of body growth ▪ Ends with attainment of adult heigh • Life History ◦ Derived features of human life history ▪ Long post-reproductive lifespan ▪ Late age at first birth ▪ Long gestation length ▪ Large neonates ▪ Early age at weaning (—> childhood) ▪ Short inter-birth interval
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