1. IB Biology Option D D3 Human Evolution IB Biology Option D D3 Human Evolution 1

2. D.3.1 Outline the method for dating rocks and fossils using radioisotopes, with reference to 14 C and 40 K. 14 C is a naturally occurring isotope of carbon with a half life of 5730 years. Constantly being made in the atmosphere when cosmic rays cause neutrons to fuse with nitrogen nuclei and “kick out” protons Formation Decay http://www.youtube.com/watch?v=2io5opwhQMQhttp://www.youtube.com/watch?v=2io5opwhQMQ Carbon dating – Mr. Andersen 2

3. D.3.1 Outline the method for dating rocks and fossils using radioisotopes, with reference to 14 C and 40 K. 14 C production is in equilibrium with its decay to 12 C The 14 C is incorporated in carbon dioxide which is then taken up by plants. In the end all living things have the same ratio of 14 C to 12 C When an organism dies it no longer takes in 14 C. So over time the ratio of 14 C to 12 C changes. This is measurable and can be used to estimate age. The limit for accurate determination of age is about 50,000y 3

4. 40 K is an isotope with a half life of 1.3 X 10 9 y 40 K decays to 40 Ar. When 40 K is released from a volcano in lava all of the argon gas is driven off. So brand new rocks effectively have a ratio 40 K: 40 Ar of 100:0 Over time the lava may be weathered and eroded and incorporated into sedimentary rocks. The measured ratio of 40 K to 40 Ar can be used to date rocks over one million years old with an accuracy of around 50000 years D.3.1 Outline the method for dating rocks and fossils using radioisotopes, with reference to 14 C and 40 K. 4

5. D.3.1 Outline the method for dating rocks and fossils using radioisotopes, with reference to 14 C and 40 K. When to use which isotope? Rocks - K-40 - For older samples, over 100,000 years old Fossils - C-14/C-13/C-12 - For young samples, from 1000 to 100,000 years old - Lots C14 recent death; little C14, old! 5

6. D.3.2 Define half-life. Half-life = The time it takes for half of a radioactive isotope to decay 6

7. D.3.2 Define half-life. Half-life = The time it takes for half of a radioactive isotope to decay What is the half life for each of the isotopes represented by these curves? 7

8. 3.420.130.7 ?.?? D.3.2 Define half-life. 8

9. D.3.3 Deduce the approximate age of materials based on a simple decay curve for a radioisotope. Play the game 9

10. D.3.4 Describe the major anatomical features that define humans as primates. human gibbon gorilla Grasping pentadactyl limbs http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.htmlhttp://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html Did Humans Evolve? (PBS) 10

11. Binocular Vision D.3.4 Describe the major anatomical features that define humans as primates. 11

12. Reduced snout leading to reduced olfaction vs. Squirrel Doggie Monkey Human D.3.4 Describe the major anatomical features that define humans as primates. Monkey 12

13. Generalized Dentition Human Baboon Gorilla Moo Cown D.3.4 Describe the major anatomical features that define humans as primates. 13

14. Others: Forelimbs able to twist Clavicle allows wide range of arm movement (re. the above two points: if you have a gentle and patient pet dog, give it a rub on the tummy and then move it’s forelegs, they really only move in one plane) Slower reproduction - long gestation - usually one offspring at a time Larger skull – relative to body size Large brain – more complex, more folds Better visual acuity – more of the photoreceptors have their own sensory neurons Social dependency D.3.4 Describe the major anatomical features that define humans as primates. 14

15. D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 15

16. D.3.5 Outline the trends illustrated by the fossils of: approximate dates distribution Ardipithecus ramidus 5.8 mya – 4.4 mya Ethiopia; similar to chimpanzee Australopithecus: A. afarensis 4 mya – 2.5 mya Eastern Africa; “Lucy” A. africanus 3 mya - <2.5 mya Southern Africa 16

17. D.3.5 Outline the trends illustrated by the fossils of: 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. neandertha- lensis 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 17

18. THE HOMINIDS 18 http://humanorigins.si.edu/resources/multimedia/videos What does it mean to be human? (Smithsonian National Museum of Natural History)

19. Australopithecus afarensis © 2008 Paul Billiet ODWSODWS 3.9 – 2.9 Mya Climate changing. Antarctic ice cap advance 5 Mya Distribution: Ethiopia, Kenya, Tanzania Cranial capacity: 380 – 450 cm 3 Height: 1.07m Bipedal (footprints 3.6 Mya old) /climber U-shaped dental arcade but reduced canines Arboreal / terrestrial herbivore 19

20. Australopithecus africanus (Southern Ape of Africa) © 2008 Paul Billiet ODWSODWS 3 – 2.25 Mya Cooling of climate reduced rainfall Further advance of Antarctic ice Development of scrubland and savannah Forest cover retreats 20

21. Australopithecus africanus (Southern Ape of Africa) 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 21

22. Homo habilis Homo habilis - the handy man © 2008 Paul Billiet ODWSODWS 2.6 -1.4 Mya E. Africa Scavenging significant part of the diet Cranial capacity: 600 – 800 cm 3 Height: 1.20 – 1.35m Simple fashioned tools – choppers 22

23. Homo erectus Homo erectus – the upright man © 2008 Paul Billiet ODWSODWS 1.8 to 0.5 Mya 0.9 Mya beginning of the Pleistocene ice age Oscillations between cold and warm periods Spread out of Africa (  1.6Mya) throughout the old world Scavenging to hunting Use of a home base 23

24. Homo erectus – the upright man 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 © 2008 Paul Billiet ODWSODWS 24

25. Homo neanderthalensis Homo neanderthalensis (our distant cousins?!) © 2008 Paul Billiet ODWSODWS 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 25 http://www.youtube.com/watch?v=P-fyqQSKpGY&feature=player_embeddedhttp://www.youtube.com/watch?v=P-fyqQSKpGY&feature=player_embedded Meanderthal

26. Homo neanderthalensis (our distant cousins?!) Cranial capacity: 1400 cm 3 (H. sapiens = 1350 cm 3 ) Brow ridge, long low skull Height: 1.67m Stocky build Improved sophisticated tools Sometimes buried their dead Made simple jewelry © 2008 Paul Billiet ODWSODWS 26

27. Homo sapiensHomo sapiens – Modern Human © 2008 Paul Billiet ODWSODWS 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 27

28. Homo sapiens – Modern Human 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 28

29. Ardipithecus ramidus Australopithecus africanus Australopithecus afarensis Homo habilis Homo erectus Homo neanderthalensis Homo sapiens **Skulls not to scale 29

30. Australopithecine Gorilla Homo erectus Neanderthal Modern human 30

31. From the previous two slides you can see: enlargement of the brain case shortening of the face loss of brow ridges You can’t really see it but the hole in the bottom of the skull where the spinal cord exits the brain (foramen magnum) is further forward in modern humans. This distributes the weight of the head over the spine so that modern humans do not need huge necks muscles. D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 31

32. Homo sapiens Pan troglodytes (chimpanzee) D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 32

33. The jaw has developed from a U into a V shape. Teeth have generally reduced in size. (Chimpanzee provided for comparison) D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 33

34. Human hands are adapted for grasping and fine manipulation. In contrast gorillas have short fingers for knuckle walking and gibbons have elongated fingers and reduced thumbs for brachiating. D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 34

35. Skeleton, locomotion and posture Human knees aligned under the body’s centre of gravity because femurs are angled inwards. Human legs straighten completely when walking. Human spine has additional curves to keep centres of mass of head and trunk aligned for bipedalism. Big toe not opposable in humans, which allows for an arched foot. Ratio legs:arms greater for humans than other apes Human pelvis broader D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 35

36. Neoteny, also called juvenilization or pedomorphism, is the retention, by adults in a species, of traits previously seen only in juveniles. D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens.

37. D.3.5 Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including A. afarensis and A. africanus, and Homo including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. 37 Some human characteristics thought to be a result of Neoteny: Lack of body hair Small teeth and reduced numbers of teeth Prolonged growth period Long life span Flat face and thin skull bones Lactase production in adults Epicanthic eye fold Small nose Longer trunk relative to arms and legs 37

38. D.3.6 State that, at various stages in hominid evolution, several species may have coexisted. Doesn’t necessarily mean they lived together/near each other...just means fossils present at same time A. afarensis & A. africanus ~ 3mya A. africanus & H. habilis ~2mya H. neanderthalensis, H. erectus, and H. sapiens ~100,000 yrs ago 38

39. THE CHANGING TREES OF HUMAN EVOLUTION © 2008 Paul Billiet ODWSODWS 39

40. 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 40 Australopithecus Homo erectus Homo sapiens

41. 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 41

42. 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 42

43. 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 43

44. 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 44

45. D.3.6 State that, at various stages in hominid evolution, several species may have coexisted. 45

46. 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: fossils only form when buried under sediment before decomposition occurs; animal bodies are usually eaten by detrivores, decomposed by bacteria, or broken down chemically of remains fossilized, most remain buried in sediment/ remain unfound; Measurements imprecise b/c age differences of organisms at death (juvenile  adult) 46

47. 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: hominid fossils that have been found may or may not be representative of hominid history; hominid fossils that have been found are usually partial, and the remainder of the organism must be inferred/ inferences may or may not be correct; only hard parts of individuals fossilize, leaving many questions concerning the rest of the individual’s phenotype; 47

48. The large gaps in the human evolution fossil record are consistent with punctuated equilibrium The following four slides show how the gaps are filled over time with new discoveries. The graphs plot cranial size against the age of the fossil. D.3.7 Discuss the incompleteness of the fossil record and the resulting uncertainties about human evolution. 48

49. D.3.8 Discuss the correlation between the change in diet and increase in brain size during hominid evolution. The benefits of a bigger brain include: More complex tools Mastery of fire Cooking Warmth Protection Greater behavioral flexibility (less reliance on instinct and better able to learn and pass on knowledge necessary to adapt to an environment) 49

50. The cost of having a big brain: Longer gestation period Years of development before young can look after themselves Much more brain development occurs post birth that for any other animal D.3.8 Discuss the correlation between the change in diet and increase in brain size during hominid evolution. 50

51. In summary: Big brains are energetically expensive. The mother must take in lots of energy not only during pregnancy, but for a significant time after. Hominids needed to increase their energy uptake. D.3.8 Discuss the correlation between the change in diet and increase in brain size during hominid evolution. 51

52. The solution to this energy crisis was to swap a diet of these: http://www.flickr.com/photos/heydrienne/22080973/ D.3.8 Discuss the correlation between the change in diet and increase in brain size during hominid evolution. 52

53. For some chunks of this: The increase in brain size observed in hominid fossils has been closely correlated with an increased intake of meat. A bigger brain made hunting and killing easier D.3.8 Discuss the correlation between the change in diet and increase in brain size during hominid evolution. 53

54. D.3.9 Distinguish between genetic and cultural evolution. Genetic evolution refers to the genetic changes that have occurred during the evolution of hominids. e.g. increased brain size, spine shape, position of knee Cultural evolution is the changing of ideas held and actions carried out by societies and the transmission of these ideas through social learning from one generation to the next. e.g. the use of fire, agriculture, tools, weapons, religion, beliefs 54

55. D.3.9 Distinguish between genetic and cultural evolution. Genetic Inherited, parent to child only Body morphology (e.g. increased brain size, spine shape, position of knee) # chromosomes Biochemicals Cultural Acquired knowledge, passed on to many in the group/family, generation to generation (e.g. the use of fire, agriculture, tools, weapons, religion, beliefs) Language Customs/rituals Art Technology 55

56. 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 D.3.9 Distinguish between genetic and cultural evolution. 56