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D3: Human Evolution 6 hours Smithsonian "Human Origins" Website
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D.3.1 Outline the method for dating rocks and fossils using radioisotopes, with reference to C-14 and K-40. Proportion of radioactive isotope to other isotopesProportion of radioactive isotope to other isotopes Knowledge of the degree of accuracyKnowledge of the degree of accuracy Choice of isotope to useChoice of isotope to use RocksRocks –K-40 –100,000 to 4.6 bya FossilsFossils –C-14/C-13/C-12 –Lots C14 recent death; little C14, old!
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D.3.2Define half-life. Amount of time it takes for half the radioactive isotope to decayAmount of time it takes for half the radioactive isotope to decay
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D.3.3Deduce the approximate age of materials based on a simple decay curve for a radio-isotope. P. 435P. 435 Textbook examples too!Textbook examples too!
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D.3.4Describe the major anatomical features that define humans as primates. Opposable thumbs... Grabbing!Opposable thumbs... Grabbing! Long, thin, straight fingers... Motor skills!Long, thin, straight fingers... Motor skills! Finger pads, finger printsFinger pads, finger prints No claws, but fingernailsNo claws, but fingernails Shoulder with large range of motion (circular)... Swing through trees! ;)Shoulder with large range of motion (circular)... Swing through trees! ;) Forward-facing eyes... Stereoscopic vision (seeing in 3D, judging distances)Forward-facing eyes... Stereoscopic vision (seeing in 3D, judging distances)
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D.3.5Outline the trends illustrated by the fossils of... Knowledge of approximate dates and distribution of the named species is expected. Details of subspecies or particular groups (Cro- Magnon, Peking, and so on) are not required.Knowledge of approximate dates and distribution of the named species is expected. Details of subspecies or particular groups (Cro- Magnon, Peking, and so on) are not required. approximate datesdistribution Ardipithecus ramidus 5.8 mya – 4.4 myaEthiopia; sim to chimpanzee Australopithecus: A. afarensis 4 mya – 2.5 myaEastern Africa; “Lucy” A. africanus 3 mya - <2.5 myaSouthern Africa Homo: H. habilis 2.4 mya – 1.6 myaOlduvai Gorge (Tanzania), Kenya, Ethiopia, South Africa; simple stone tools, fire, cave- dwelling H. erectus 1.8 mya – 100,000 yaEurope, India, China, Indonesia, Africa H. neanderthalensis 200,000 – 30,000 yaEurope, Western Asia; larger brain than modern human! H. sapiens 140,000 – 70,000 yaAfrica, Europe, Asia; cave paintings; tool technology/weapons
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THE HOMINIDS © 2008 Paul Billiet ODWSODWS
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Australopithecus afarensis © 2008 Paul Billiet ODWSODWS
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Australopithecus afarensis 3.9 – 2.9 Ma Climate changing. Antarctic ice cap advance 5 Ma Distribution: Ethiopia, Kenya, Tanzania Cranial capacity: 380 – 450 cm 3 Height: 1.07m Bipedal (footprints 3.6 Ma old) /climber U-shaped dental arcade but reduced canines Arboreal / terrestrial herbivore © 2008 Paul Billiet ODWSODWS
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Australopithecus africanus © 2008 Paul Billiet ODWSODWS
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Australopithecus africanus 3 – 2.25 Ma Cooling of climate reduced rainfall Further advance of Antarctic ice Appearance of Arctic ice 2.4Ma Development of scrubland and savannah Forest cover retreats © 2008 Paul Billiet ODWSODWS
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Australopithecus africanus Distribution: Southern and Eastern Africa Cranial capacity: 500 cm 3 (Chimp = 400cm 3 ) Bipedal 20 – 35 kg Rounder skull Parabolic dental arcade Longevity: 40 years maximum Scavenger of bone marrow/brain cases Used simple tools © 2008 Paul Billiet ODWSODWS
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Australopithecus (Paranthropus) robustus © 2008 Paul Billiet ODWSODWS
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Australopithecus (Paranthropus) robustus 2 – 1 Ma Cooling of climate reduced rainfall Development of scrubland and savannah Forest retreats Distribution: S. Africa Diet: Roots and tough fibrous vegetable matter Cranial capacity: 500 cm 3 (Chimp = 400cm 3 ) Bipedal 40 –70 kg Sexual dimorphism (males twice as bulky as females) Large cheek teeth Heavy muscular skull © 2008 Paul Billiet ODWSODWS
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Homo habilis Homo habilis - the handy man © 2008 Paul Billiet ODWSODWS
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Homo habilis 2.6 -1.4 Ma E. Africa Scavenging significant part of the diet Cranial capacity: 600 – 800 cm 3 Height: 1.20 – 1.35m Simple fashioned tools – choppers (Oldowan culture) © 2008 Paul Billiet ODWSODWS
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Homo erectus Homo erectus – the upright man © 2008 Paul Billiet ODWSODWS
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Homo erectus 1.8 to 0.5 Ma 0.9 Ma beginning of the Pleistocene ice age Oscillations between cold and warm periods Spread out of Africa (1.6Ma) throughout the old world Scavenging to hunting Use of a home base © 2008 Paul Billiet ODWSODWS
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Homo erectus Cranial capacity: 850 – 1100 cm 3 (H. sapiens = 1350 cm 3 ) Use of fire Height 1.55 to 1.8m Extended childhood 1st molar at 4.6 years old (H. sapiens = 5.9y) Greater longevity 52 years Speech? (Brain says: yes; spine says: no) Improved tools: Hand axes (Acheulian culture) © 2008 Paul Billiet ODWSODWS
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Homo neanderthalensis © 2008 Paul Billiet ODWSODWS
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Homo neanderthalensis 250 000 to 28 000 years ago Europe, Middle East, into Central Asia Evolved from H. erectus populations perhaps via H. heidelbergensis, then became extinct Adapted to the ice-age conditions of temperate zone Large nose may have warmed cold air The enigma of its extinction is not explained © 2008 Paul Billiet ODWSODWS
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Homo neanderthalensis Cranial capacity: 1400 cm 3 (H. sapiens = 1350 cm 3 ) Brow ridge, long low skull Height: 1.67m Stocky build Improved sophisticated tools (Mousterian culture) Sometimes buried their dead Made simple jewellery © 2008 Paul Billiet ODWSODWS
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Homo sapiens © 2008 Paul Billiet ODWSODWS
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Homo sapiens From 150 000 years ago to present Originating in Southern Africa then went worldwide Reached Europe about 50 000 years ago Cooling of the climate during the last glacial period from about 50 000a led to their predominance over other species (e.g. H. neanderthalensis) Omnivore Alters environment Domestication of species, farming © 2008 Paul Billiet ODWSODWS
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Homo sapiens Cranial capacity: 1350 cm 3 (range 1000 to 2000 cm 3 ) 20% of the body’s energy consumption for 5% of body mass Speech Art Extensive tool kit including new materials (bone, ivory, antler) Symbolic thought 1st molar tooth 5.9 years old Longevity 66 years © 2008 Paul Billiet ODWSODWS
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D.3.6State that, at various stages in hominid evolution, several species may have coexisted. Doesn’t nec. mean they lived together/near each other...just means fossils present at same timeDoesn’t nec. mean they lived together/near each other...just means fossils present at same time P.439 graphic--P.439 graphic-- A. afarensis & A. africanusA. afarensis & A. africanus ~ 3mya A. africanus & H. habilisA. africanus & H. habilis~2mya H. neanderthalensis, H. erectus, and H. sapiensH. neanderthalensis, H. erectus, and H. sapiens ~100,000 yrs ago
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D.3.7Discuss the incompleteness of the fossil record and the resulting uncertainties about human evolution. Reasons for the incompleteness of the fossil record should be included. –Have to be able to FIND the fossil! –Must be well-preserved –Politics…some countries don’t allow digs –Funding! –Old fossils are in worst condition –Hominid population was relatively small back then, so odds of finding… –Some species-many fossils found –Others- only a few found –Measurements imprecise b/c age differences of organisms at death (juvenile adult) –Results in variable data-sets, multiple hypotheses; new data refutes/supports. TOK: Paleoanthropology is an example of the diverse aspects of science, in that it is a data- poor science with largely uncontrollable subject matter. Paradigm shifts are more common in a data-poor science. The discovery of small numbers of fossils has caused huge changes in theories of human evolution, perhaps indicating that too much has been constructed on too little. Conversely, discoveries such as those made in Dmanisi, Georgia, provide examples of falsification of earlier held positions indicating why paleoanthropology can be considered a science.
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THE CHANGING TREES OF HUMAN EVOLUTION © 2008 Paul Billiet ODWSODWS
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1960Up the ladder The idea that one species smoothly evolves from one into another is regarded today as an oversimplification Unfortunately it is a very persistent view that continually resurfaces in cartoons © 2008 Paul Billiet ODWSODWS Public Domain Images
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Up the ladder Australopithecus Homo erectus Homo sapiens © 2008 Paul Billiet ODWSODWS
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1970 Branching out The 1960s and 1970s were a fertile period for fossil hunting in Africa The idea developed that more than one hominid species existed at the same time developed Homo sapiens Homo erectus Homo habilis Australopithecus africanus A. robustus A. boisei Australopithecus afarensis “Lucy” Added 1974 © 2008 Paul Billiet ODWSODWS
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1991 Changing status As more specimens were found a clearer idea developed of the relationships between them Homo sapiens Homo erectus Homo habilis A. africanus A. robustus A. boisei Australopithecus afarensis © 2008 Paul Billiet ODWSODWS
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2001 From a tree to a bush ? ? ? 1 Ma 2 Ma 3 Ma 4 Ma Homo sapiens Homo erectus Homo habilis A. africanus P. robustus Paranthropus boisei Australopithecus afarensis Australopithecus anemensis Ardipithecus ramidus P. aethiopicus Homo rudolfensis H. ergaster H. heidelbergensis Homo neanderthalensis A. garhi ? ? ? © 2008 Paul Billiet ODWSODWS
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2003 DEEPER ROOTS ? ? ? ? ? ? ? ? 1 Ma 2 Ma 3 Ma 4 Ma 5 Ma 6 Ma 7 Ma Homo sapiens Homo erectus Homo habilis A. africanus Paranthropus robustus Paranthropus. boisei Australopithecus afarensis Australopithecus anemensis Ardipithecus ramidus P. aethiopicus Homo rudolfensis H. ergaster H. heidelbergensis Homo neanderthalensis A. garhi Orrorin tugensis Gorilla gorilla Sahelanthropus tchadensis “Toumai” Pan trogolodites © 2008 Paul Billiet ODWSODWS
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How many more? An estimated number of 16 hominid species is thought to have existed This is based on the evolutionary patterns of other primates Our family tree is similar to other species Periods of radiation Separated by periods of extinction © 2008 Paul Billiet ODWSODWS
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D.3.8Discuss the correlation between the change in diet and increase in brain size during hominid evolution. Xref- correlation- 1.1.6 Bigger brain...need more energy!Bigger brain...need more energy! –More food in diet or –energy & protein-rich food Hominids! (more meat in diet) Hunting tools, social groupsHunting tools, social groups Better diet feeds bigger brainBetter diet feeds bigger brain Bigger brain then allows tool development, hunting techniques, etc.Bigger brain then allows tool development, hunting techniques, etc. Further skills...cooking food easier to digest, less energy requiredFurther skills...cooking food easier to digest, less energy required Problem...Neanderthals had HUGE brains...Problem...Neanderthals had HUGE brains...
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D.3.9Distinguish between genetic evolution & cultural evolution. Genetic –Inherited, parent to child only –Body morphology –# chromosomes –Biochemicals Cultural –Acquired knowledge, passed on to many in the group/family, generation to generation –Language –Customs/rituals –Art –Technology
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GENETIC VERSES CULTURAL EVOLUTION Mousterian tools Jonzac, France
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Comparison GENETICCULTURAL The product of natural selection The product of learning. the transmission of acquired behaviour characteristics DarwinianLamarkian Innate not modified during the organism’s life time Learned during the life time Passed on through hereditary information Passed on to kin (family), social group, population, within a generation and between generations Slow changeFast change © 2008 Paul Billiet ODWSODWS
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The relative importance of genetic and cultural evolution for humans Not limited to humans examples found amongst birds and non-human primates Genetic evolution determines features such as basic anatomy e.g. maximum cranial capacity that in turn will determine “intelligence” This sets the possible scope of cultural evolution © 2008 Paul Billiet ODWSODWS
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Hominid cultures are associated with particular tools Homo habilisOldowan culture Simple choppers, scrapers and flakes Homo erectus Acheulian culture Hand axes, cleaver and pick added to the tool box Homo neanderthalensis Mousterian culture Large flakes of uniform size produced from a core; these were then trimmed to the desired tool Homo sapiens Soultrian culture Delicate blades formed, knives, burins (for drilling); other materials added (bone, antler, and ivory). Some tools now ceremonial © 2008 Paul Billiet ODWSODWS
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This implies genetic evolution had to precede cultural evolution Development of cultural innovation sometimes occurs a long time after the species evolves genetically But when it happens it spreads quickly Observed evolution of cultures © 2008 Paul Billiet ODWSODWS
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Example Homo sapiens evolved a large cranial capacity and modern brain structure 150 000 years ago Signs of symbolic thought processes in sculpture, wall paintings and adornments do not appear until 35 000 years ago A fundamental change is thought to have occurred about 60 to 70 000 years ago But is this an artefact of preservation? © 2008 Paul Billiet ODWSODWS
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D.3.10Discuss the relative importance of genetic and cultural evolution in the recent evolution of humans. Xref- correlation- 1.1.6 Brain size increased tool making alsoBrain size increased tool making also Genetic evolution probably preceded cultural b/c need big brain to improve toolsGenetic evolution probably preceded cultural b/c need big brain to improve tools Recent (30,000 yrs) H. sapiens evolution mostly cultural (little morphological changes)Recent (30,000 yrs) H. sapiens evolution mostly cultural (little morphological changes) Human culture has evolved drasticallyHuman culture has evolved drastically –Languages, art, shelter-building, agriculture, metalwork, science! –Seems to be a lag between gen & cultural evol. TOK: This is an opportunity to enter into the nature/nurture debate. There is clear causation when a genetic factor controls a characteristic. Cultural factors are much more complex, and correlation and cause are more easily confused.TOK: This is an opportunity to enter into the nature/nurture debate. There is clear causation when a genetic factor controls a characteristic. Cultural factors are much more complex, and correlation and cause are more easily confused.
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