D3: Human Evolution 6 hours

D3: Human Evolution 6 hours
Smithsonian "Human Origins" Website

Proportion of radioactive isotope to other isotopes
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 isotopes Knowledge of the degree of accuracy Choice of isotope to use Rocks K-40 100,000 to 4.6 bya Fossils C-14/C-13/C-12 Lots C14 recent death; little C14, old!

Amount of time it takes for half the radioactive isotope to decay
D.3.2 Define half-life. Amount of time it takes for half the radioactive isotope to decay

P. 435 Textbook examples too!
D.3.3 Deduce the approximate age of materials based on a simple decay curve for a radio-isotope. P. 435 Textbook examples too!

Opposable thumbs ... Grabbing!
D.3.4 Describe the major anatomical features that define humans as primates. Opposable thumbs ... Grabbing! Long, thin, straight fingers ... Motor skills! Finger pads, finger prints No claws, but fingernails Shoulder with large range of motion (circular)... Swing through trees! ;) Forward-facing eyes... Stereoscopic vision (seeing in 3D, judging distances)

D.3.5 Outline 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. approximate dates distribution Ardipithecus ramidus 5.8 mya – 4.4 mya Ethiopia; sim to chimpanzee Australopithecus: A. afarensis 4 mya – 2.5 mya Eastern Africa; “Lucy” A. africanus 3 mya - <2.5 mya Southern Africa Homo: H. habilis 2.4 mya – 1.6 mya Olduvai Gorge (Tanzania), Kenya, Ethiopia, South Africa; simple stone tools, fire, cave-dwelling H. erectus 1.8 mya – 100,000 ya Europe, India, China, Indonesia, Africa H. neanderthalensis 200,000 – 30,000 ya Europe, Western Asia; larger brain than modern human!  H. sapiens 140,000 – 70,000 ya Africa, Europe, Asia; cave paintings; tool technology/weapons

Australopithecus afarensis
© 2008 Paul Billiet ODWS

3.9 – 2.9 Ma Climate changing. Antarctic ice cap advance 5 Ma Distribution: Ethiopia, Kenya, Tanzania Cranial capacity: 380 – 450 cm3 Height: 1.07m Bipedal (footprints 3.6 Ma old) /climber U-shaped dental arcade but reduced canines Arboreal / terrestrial herbivore © 2008 Paul Billiet ODWS

Australopithecus africanus

Distribution: Southern and Eastern Africa Cranial capacity: 500 cm3 (Chimp = 400cm3) 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 ODWS

Australopithecus (Paranthropus) robustus

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 cm3 (Chimp = 400cm3) Bipedal 40 –70 kg Sexual dimorphism (males twice as bulky as females) Large cheek teeth Heavy muscular skull © 2008 Paul Billiet ODWS

Homo habilis - the handy man

Homo habilis 2.6 -1.4 Ma E. Africa
Scavenging significant part of the diet Cranial capacity: 600 – 800 cm3 Height: 1.20 – 1.35m Simple fashioned tools – choppers (Oldowan culture) © 2008 Paul Billiet ODWS

Homo erectus – the upright man

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 ODWS

Homo erectus Cranial capacity: 850 – 1100 cm3 (H. sapiens = 1350 cm3)
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 ODWS

Homo neanderthalensis

to 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 ODWS

Cranial capacity: 1400 cm3 (H. sapiens = 1350 cm3) 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 ODWS

Homo sapiens From 150 000 years ago to present
Originating in Southern Africa then went worldwide Reached Europe about years ago Cooling of the climate during the last glacial period from about a led to their predominance over other species (e.g. H. neanderthalensis) Omnivore Alters environment Domestication of species, farming © 2008 Paul Billiet ODWS

Homo sapiens Cranial capacity: 1350 cm3 (range 1000 to 2000 cm3)
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 ODWS

A. afarensis & A. africanus A. africanus & H. habilis
D.3.6 State 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 time P.439 graphic-- A. afarensis & A. africanus ~ 3mya A. africanus & H. habilis ~2mya H. neanderthalensis, H. erectus, and H. sapiens ~100,000 yrs ago

D.3.7 Discuss 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.

THE CHANGING TREES OF HUMAN EVOLUTION

1960 Up 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 Public Domain Images © 2008 Paul Billiet ODWS

Up the ladder Homo sapiens Homo erectus Australopithecus

Branching out Homo sapiens Homo erectus Homo habilis Australopithecus africanus A. robustus A. boisei Australopithecus afarensis “Lucy” Added 1974 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 © 2008 Paul Billiet ODWS

Changing status Homo sapiens Homo erectus Homo habilis A. africanus A. robustus A. boisei Australopithecus afarensis As more specimens were found a clearer idea developed of the relationships between them © 2008 Paul Billiet ODWS

2001 From a tree to a bush Homo sapiens Homo neanderthalensis
? 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 ODWS

2003 DEEPER ROOTS ? 1 Ma 2 Ma 3 Ma 4 Ma 5 Ma 6 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 ODWS

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 ODWS

Bigger brain...need more energy!
D.3.8 Discuss the correlation between the change in diet and increase in brain size during hominid evolution. Xref- correlation Bigger brain...need more energy! More food in diet or energy & protein-rich food  Hominids! (more meat in diet) Hunting tools, social groups Better diet feeds bigger brain Bigger brain then allows tool development, hunting techniques, etc. Further skills...cooking food  easier to digest, less energy required Problem...Neanderthals had HUGE brains...

D.3.9 Distinguish between genetic evolution & cultural evolution.
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

GENETIC VERSES CULTURAL EVOLUTION
Mousterian tools Jonzac, France

Comparison GENETIC CULTURAL The product of natural selection
The product of learning. the transmission of acquired behaviour characteristics Darwinian Lamarkian 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 change Fast change © 2008 Paul Billiet ODWS

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 ODWS

Hominid cultures are associated with particular tools
Homo habilis Oldowan 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 ODWS

Observed evolution of cultures
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 © 2008 Paul Billiet ODWS

Example Homo sapiens evolved a large cranial capacity and modern brain structure years ago Signs of symbolic thought processes in sculpture, wall paintings and adornments do not appear until years ago A fundamental change is thought to have occurred about 60 to years ago But is this an artefact of preservation? © 2008 Paul Billiet ODWS

Brain size increased  tool making also
D.3.10 Discuss the relative importance of genetic and cultural evolution in the recent evolution of humans. Xref- correlation Brain size increased  tool making also Genetic evolution probably preceded cultural b/c need big brain to improve tools Recent (30,000 yrs) H. sapiens evolution mostly cultural (little morphological changes) Human 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.

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