Lucy in Texas. Fig. RT Bakker

Transcription

1 Lucy in Texas Fig. RT Bakker 1

2 What is so special about Lucy? Oldest nearly complete skeleton of a hominid that shows human characteristics 2

3 Ancestors from Africa Hadar 3

4 Famous Early Man Locations 4

5 Volcanoes in the Afar Triangle 3 moving plates split the crust Volcanoes produce ash that causes mineralization of bones Low elevations cause lakes and swamps during wet periods Food for animals 5

6 Hadar, Ethiopia 6

7 Other A. afarensis site -Sterkfontein Sinkhole collecting bones No volcanic ash layer for age dating 7

8 Probably has a more complete skeleton than Lucy Bones are imbedded in flow stone and are very well preserved 8

9 Leopards like to eat primates! Many skulls have 4 bite marks Leopards drag their prey into trees to keep them away from hyenas 9

10 Putting it in perspective How are modern monkeys and great apes related using DNA? Extrapolate that backwards to the extinct great apes 10

11 DNA-based similarity 11

12 12

13 Family Tree Australopithecus afarensis = Southern Ape from Afar = Lucy 13

14 Lucy In Context From apes to humans 14

15 15

16 Gorilla No fossil record! Ape features no chin, big fangs, brow ridge 16

17 Chimp No fossil record! Ape features no chin, big fangs, brow ridge. 17

18 Sahelanthropustchadensis 6,500,000 ybp Chad, Africa Brain 350 cc Ape 18

19 Kenyanthropus platyops 3,500,000 ybp Brain? Kenya, Africa Ape 19

20 Australopithecus afarensis 3,600,000 ybp Olduvai, Kenya Ape but with an arched foot and a non separated big toe 20

21 Australopithecus afarensis 3,100,000 ybp Hadar, Ethiopia Lucy! Brain 430 cc Though it has small fangs, the small brain makes it an ape 21

22 Australopithecus africanus 2,600,000 ybp From a cave in South Africa Brain 500 cc The small brain makes it an ape 22

23 Australopithecus boisei 1,800,000 ybp Olduvai, Kenya Brain 480 cc The small brain makes it an ape. The huge teeth indicate a plant diet Evolutionary dead end 23

24 Homo habilis (handy man) 1,800,000 ybp Olduvai, Kenya Brain 650 cc First use of simple stone tools makes this a man (Homo) Small teeth, and small brow ridge 24

25 Stone tools made by H. habilis 1,800,000 ybp Olduvai, Kenya A man because: Hammer stones to break bones for marrow Sharp edges to butcher meat 25

26 Homo erectus (Peking man) 1,600,000 ybp Peking, China Brain 900 cc A man because of the brain size and small teeth No stone tools?? 26

27 Homo ergaster (working man) 1,500,000 ybp Kenya Brain 880 cc First flaked stone tools A man because of the tools 27

28 Stone tools - Homo ergaster 1,500,000 ybp Kenya, Africa Mass manufacturing of 1000s of stone tools 28

29 Homo heidelbergensis 120,000 ybp South Africa Brain 1300 cc Nearly modern brain size 29

30 Homo neanderthalensis 45,000 ybp Israel Brain 1600 cc Used fire and throwing sticks without flint points Modern brain size Massive teeth 30

31 Cro-magnon Homo sapiens 195,000 ybp Ethiopia Brain 1600 cc Earliest modern man found Overlap with H. neanderthalensis 31

32 Lucy is an Ape Ape characteristics small brain, brow ridge,moderate canine teeth, small head crest, no tools, arms can be vertical, strong wrist, curved fingers, semi-divergent big toe Human Characteristics Broad pelvis, biped (lock knees), skull centered on spine, jaw is a U, foot is arched, femur puts feet directly below pelvis 32

33 Comparisons Fig. RT Bakker 33

34 Fig. RT Bakker 34

35 Lucy vs. H. sapiens Fig. RT Bakker 35

36 What things make us Human? Well, I ve got your final grades ready, though I m afraid not everyone here will be moving up. Intelligence is hard to measure in a fossil We can measure brain size, observe tools and cultural practices 36

37 Tools Stone tools have NOT been found with Lucy These are by H. habilis and are way too advanced!! Chimps can be trained to make better tools than Lucy 37

38 Getting out of the Trees Going biped frees up the hands for tools, infant care, and permits the growth of intelligence Being bipedal does NOT = intelligence 38

39 Walking Upright Dinosaurs, birds, and humans are bipeds Not related to tool use or carrying infants Not as energy efficient as running on 4 feet but better than knuckle walking 39

40 Lucy doing the Knuckle Walk Hypothesis During an Ice Age, so much water was trapped in the ice sheets that the Mediterranean dried up and Africa also Forests declined Fig. RT Bakker 40

41 Apes moved out of the forest into the savanna. Knuckle walking is inefficient for long distance walking Fig. RT Bakker 41

42 Femur Bent to put the feet under the pelvis Huge end to allow the knee to lock Pelvis Wide to support the back 42

43 Big Toe as a Thumb The big toe on an Orangutan is a functional thumb Lucy has a big toe for walking 43

44 Shoulders and Wrists For Apes and Lucy, the shoulder allows the arm to be vertical H. sapiens has to strain to hold arm vertical Bones have enlarged muscle attachments for strength at the expense of quickness 44

45 Brain Connection Ape Man 45

46 Language A. afarensis has a hyoid bone. But that does not mean they could speak It is the position of the bone relative to the larynx that is key 46

47 Bipeds = strange back design This is why your back hurts 47

48 Lower Jaws: hominids = broad U Chimp 48

49 Biped = broad pelvis to support the back Homo sapiens has a really broad pelvis for the babies skull 49

50 Costs for being Intelligent Human Pelvis female male Modern brain uses 20% of energy Human infant is born with ¼ of ultimate brain size forcing long infancy Hard birth process Chimp 50

51 Skull Crests = chewing power Gorilla A. boisei 51

52 Firsts in Human Evolution Mybp Firsts Biped Simple Tools Hand Axes Moved Asia Moved Europe Fire Art, Burial Agriculture Who? A. afarensis H. habilis H. ergaster H. erectus H. heidelbergensis H. neanderthalensis Cro-magnon H. sapiens Modern man 52

53 How old are the fossils? Radioactive Dating Mass Spectrometry accelerates ions in a magnetic field Different masses follow different paths 53

54 Radioactive parent element > normal daughter element 54

55 K40/Ar40 and Ar39/Ar40 looks for argon trapped in the crystal 55

56 Elapsed time since the crystal cooled Drawing by Dr. Bakker 56

57 Drawing by Dr. Bakker 57

58 Ar39/Ar40 Correct for weathering by progressive heating 58

59 What do you date? Date every ash layer and lava you can find Hopefully they will bracket the fossils you want to date Olduvai Gorge Basalt 59

60 Drawing by Dr. Bakker 60

61 Drawing by Dr. Bakker 61

62 Drawing by Dr. Bakker 62

63 Biostratigraphic Dating Pigs and Elephants evolve through time and are much more abundant and durable Match the hominid fossil to another dated fossil and you can predict the age 63

64 The more things change, the more they stay the same. 64

65 Houston Museum of Natural Science will host Lucy from September 1 to April 20 Don t wait until the last minute to see this show 65

66 More to see at HMNS! Verdura: the Life and Work of a Master Jeweler June 1, January 6, 2008 November February 17,