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Hominid Evolution Chapter 19. Classification Hierarchy (Linnaeus) Kingdom Animal Phylum Chordate Class Mammal Order Primates Family Hominids Genus Homo.

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Presentation on theme: "Hominid Evolution Chapter 19. Classification Hierarchy (Linnaeus) Kingdom Animal Phylum Chordate Class Mammal Order Primates Family Hominids Genus Homo."— Presentation transcript:

1 Hominid Evolution Chapter 19

2 Classification Hierarchy (Linnaeus) Kingdom Animal Phylum Chordate Class Mammal Order Primates Family Hominids Genus Homo Species Sapiens Humans and apes diverged ~8 Mya

3 Humans and Apes Diverged ~8 million years ago >12 different forms of hominids since then

4 Sahelanthropus tchadensis, –the oldest known hominid –7 million years old –discovered in 2002 in Chad Oldest Hominid

5 Skull found in the African nation of Chad in 2002 –pushed back the origins of humans to nearly 7 million years ago –its discovery has raised more questions than it answered Sahelanthropus tchadensis

6 Paleoanthropologists now think –human evolution branched many times –rather than evolving in a somewhat straight line Key traits such as upright walking manual dexterity “large” brain –evolved more than once, and produced many evolutionary dead-ends “Bushy” Model of Human Evolution

7 Fossil hominids

8 Sahelanthropus tchadensis shows a mosaic of primitive and advanced features The small brain case and most of the teeth are chimplike Fairly flat nose and the prominent brow ridges –are features only seen, until now, in the human genus Homo Looks more human than hominids that came millions of years later! Oldest Hominid

9 Much of our knowledge –comes from fossils found in a small desert area southwest of Cairo, Egypt During the Late Eocene and Oligocene –this region was a lush, tropical rain forest –supported a diverse and abundant fauna and flora Early History of Ancestral Hominids

10 Several thousand fossil specimens –representing more than 20 species of primates –recovered from rocks of this region One of the earliest ancestral hominids –was Aegyptopithecus, small, fruit-eating, arboreal primate weighed about 5 kg Thousands of Fossil Specimens

11 One of the Earliest Ancestral Hominids Skull of Aegyptopithecus zeuxis, –one of the earliest known anthropoids –~30 Ma

12 The hominids (family Hominidae) –primate family that includes present-day humans –fossil record extending back 7 million years Hominids are bipedal –that is, they have an upright posture –Skeletal structure shows bipedal traits Hominid brain organization: larger compared to other primates Hominids

13 Comparison between quadrupedal and bipedal locomotion –in gorillas and humans Comparison of Locomotion In gorillas the ischium bone is long –and the entire pelvis is tilted toward the horizontal

14 In humans the ischium bone is much shorter and the pelvis is vertical Comparison of Locomotion Comparison between quadrupedal and bipedal locomotion –in gorillas and humans

15 In addition, hominids show a trend –toward a large and internally reorganized brain A large brain size and organization –is apparent in the brain of a present-day human Hominids: Larger Reorganized Brain

16 Many anthropologists think –hominid features evolved in response to major climatic changes During this time –vast savannas replaced the African tropical rain forests –where the lower primates had been so abundant Response to Climatic Changes

17 As the savannas and grasslands continued to expand –hominids made the transition from true forest dwelling –to life in an environment of mixed forests and grasslands Mixed Forests and Grasslands

18 Geologic Age Ranges

19 Discovered in Chad in 2002 –nearly 7-million-year-old skull and dental remains of Sahelanthropus tchadensis –make it the oldest known hominid yet unearthed Oldest Known Hominid

20 Australopithecines are early hominids –genus Australopithecus Currently, five species are recognized: –A. anamensis –A. afarensis –A. africanus –A. robustus –A. boisei Australopithecus

21 Many paleontologists accept that –A. anamensis the oldest known australopithecine, –is ancestral to A. afarensis, who in turn is ancestral to A. africanus and the genus Homo, as well as the side branch of australopithecines –represented by A. robustus and A. boisei Evolutionary Scheme

22 A reconstruction of Lucy’s skeleton Lucy is a ~ 3.5-million- year-old –Australopithecus afarensis Lucy Knees worked like modern human knees Makes 40% bigger than females Males had large crests on the tops of their skulls

23 Preserved in volcanic ash in Tanzania –Discovered in 1978 –Proved hominids were bipedal walkers at least 3.5 million years ago Hominid Footprints

24 Most scientists think the footprints –were made by Australopithecus afarensis –whose fossils are found nearby

25 A. afarensis had a brain size of 380–450 cubic centimeters (cc), –larger than the 300–400 cc of a chimpanzee –much smaller than that of present-day humans (1350 cc average) Brain Size of A. afarensis

26 The skull of A. afarensis retained many apelike features –massive brow ridges –forward-jutting jaw –teeth were intermediate between those of apes and humans The heavily enameled molars –adaptation to chewing fruits, seeds, and roots Apelike Features

27 Landscape with A. afarensis Re-creation of a Pliocene landscape –showing members of –Australo- pithecus afarensis –gathering and eating –various fruits and seeds

28 A reconstruction of the skull –of Australopithecus africanus This skull, –known as that of the Taung Child, was discovered by Raymond Dart in South Africa in 1924 –and marks the beginning of modern paleoanthropology Skull of A. africanus

29 It appears the limbs –of A. africanus may not have been as well adapted for bipedalism as those of A. afarensis Not As Well Adapted for Bipedalism

30 Homo habilis The earliest member of our own genus Homo –lived 2.5-1.6 million years ago H. habilis evolved from the A. afarensis and A. africanus lineage –coexisted with A. africanus for about 200,000 years The Human Lineage: handy man

31 The geologic age ranges –for the commonly accepted species of hominids Geologic Age Ranges

32 H. habilis had a larger brain (700 cc average) –than its australopithecine ancestors but smaller teeth It was about 1.2-1.3 m tall and weighed 32-37 kg Characteristics of Homo habilis

33 In contrast to the australopithecines and H. habilis, –which are unknown outside Africa, –Homo erectus was a widely distributed species –migrated from Africa during the Pleistocene Specimens have been found –not only in Africa –also in Europe, India, China ("Peking Man"), and Indonesia ("Java Man") Homo Erectus

34 H. erectus evolved in Africa 1.8 million years ago –and by 1 million years ago –was present in southeastern and eastern Asia, –where it survived until about 100,000 years ago Survived in Asia Until About 100,000 Years Ago

35 Although H. erectus developed regional variations in form, –the species differed from modern humans in several ways Its brain size of 800-1300 cc, –though much larger than that of H. habilis, –was still less than the average for Homo sapiens (1350 cc) H. erectus Differed From Modern Humans

36 H. erectus's skull was thick-walled –face was massive –prominent brow ridges –teeth were slightly larger than those of present-day humans H. erectus was comparable to size to modern humans –between 1.6 and 1.8 m tall –weighing between 53 and 63 kg Size Similar to Humans

37 A reconstruction of the skull of Homo erectus –a widely distributed species –whose remains have been found in Africa, Europe, India, China, and Indonesia Skull of Homo erectus

38 The archaeological record indicates –that H. erectus was a tool maker Furthermore, some sites show evidence –that its members used fire and lived in caves –an advantage for those living in more northerly climates H. erectus Was a Tool Maker

39 Homo erectus Using Tools Re-creation of a Pleistocene setting in Europe –in which members of Homo erectus are –using fire and stone tools

40 Currently, a heated debate surrounds the transition –from H. erectus to our own species Homo sapiens “Out of Africa" view –early modern humans evolved from a small African colony –offspring then migrated from Africa and populated Europe and Asia, driving the earlier hominid populations to extinction The "Out of Africa" View

41 “Multiregional" view –early modern humans did not have an isolated origin in Africa –established separate populations throughout Eurasia Occasional contact and interbreeding –enabled our species to maintain its overall cohesiveness –still preserving the regional differences in people we see today The "Multiregional" View

42 Regardless of which theory turns out to be correct, –our species, H. sapiens, most certainly evolved from H. erectus Homo sapiens Evolved From H. erectus

43 Neanderthals –inhabited Europe and the Near East –200,000 to 30,000 years ago Some paleoanthropologists : –as a Neanderthals are a subspecies of our own species (Homo sapiens neanderthalensis) –Others: separate species (Homo neanderthalensis) Neanderthals

44 Main difference between Neanderthals and present-day humans is in the skull –Neanderthal skulls were long and low –heavy brow ridges, a projecting mouth, and a weak, receding chin Their brain was slightly larger on average –than our own, and somewhat differently shaped Neanderthals Difference

45 Neanderthal Skull Reconstructed Neanderthal skull The Neanderthals were characterized by prominent heavy brow ridges and weak chin

46 Given the specimens from more than 100 sites –we now know Neanderthals were not much different from us, only more robust Europe's Neanderthals were the first humans –to move into truly cold climates –enduring miserably long winters and short summers –as they pushed north into tundra ecosystems First Humans in Cold Climates

47 Burial Ceremony in a Cave Archaeological evidence indicates –Neanderthals lived in caves –and participated in ritual burials –as depicted in this painting of a burial ceremony –such as occurred approximately 60,000 years ago –at Shanidar Cave, Iraq

48 About 30,000 years ago –humans closely resembling modern Europeans –moved into the region inhabited by the Neanderthals and completely replaced them Cro-Magnons –successors of the Neanderthals in France –35,000 to 10,000 years ago –huge advances in development of art and technology Cro-Magnons

49 Cro-Magnons were cave painters Using paints made from manganese and iron oxides –painted hundreds of scenes on the ceilings and walls of caves in France and Spain –many of them are still preserved today Cave Painters

50 Cro-Magnons were very skilled cave painters –Painting of a horse –from the cave of Niaux, France Painting From a Cave in France

51 With the appearance of Cro-Magnons, –human evolution has become almost entirely cultural rather than biological Humans have spread throughout the world –by devising means to deal with a broad range of environmental conditions Cultural Evolution

52 Summary Aegyptopithecus 32 Ma (ancestral hominid – primate) –Somewhat developed forehead Australopithecus 5 Ma (early hominids) –Afarensis (Lucy) 4 Ma, bipedalism, still tree climbers, small skull –Africanus 2-3 Ma slightly larger brain Homo habilis 2 Ma –Larger brain, less pronounced brow, rounder head, smaller face –Use of stone tools Homo erectus 500 K-2Ma –Larger brain and body –Longer skull, large brow ridges Homo sapiens neanderthalensis 200 K –Large brains and bodies, lack of frontal lobes? Homo sapiens sapiens (cro-magnon) 90 K –Anatomically similar to humans

53 Climate in Human History Peak of glaciation 18 Ka Present interglacial began 10 Ka Climatic Optimum –6-7 Ka –First great civilizations in Middle East –Some collapsed 3 Ka when climate changed Subatlantic Deterioration –2.5 Ka –Reflected in art and invasions

54 Drought and famine Location of settlements Exploration Medieval Warm Period began ~950 A.D. Little Ice Age 1550-1850 A.D. Climate in Human History

55 Vikings Settled Greenland and Iceland during Medieval Warm Period During Little Ice Age, Greenland was abandoned and Iceland struggling Ice blocked trade routes, cold weather caused poor harvests Fish moved southward

56 Climate reflected in art Little Ice Age at its peak during 2 nd epoch

57 Recent History Two centuries of warm, mild climate Continual drying of northern Africa Interglacial should be coming to an end – will humans prolong it?

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