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Primate and Human Evolution main points

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Title: Primate and Human Evolution main points


1
Chapter 19
Primate and Human Evolutionmain points.1.
primates demonstrate a great deal of variation
andincreasing complexity through time.2.
hominids include present day humans and their
extinct ancestors.3. human evolution is very
complex and in constant state of flux due to new
fossil discoveries made frequently.4. most
famous fossil humans are Neanderthals, which were
suddenly succeeded by Cro-Magnons about 30,000
years ago.
2
Who are we?
  • Who are we?
  • Where did we come from?
  • What is the human genealogy?
  • These are basic questions
  • that probably everyone at some time or another
  • has asked themselves

3
Goes Back Farther Than We Thought
  • Many people enjoy tracing
  • their own family history as far back as they can,
  • similarly paleoanthropologists are discovering,
  • based on recent fossil finds
  • that the human family tree goes back
  • much farther than we thought

4
What Are Primates?
  • Primates are difficult to characterize as an
    order
  • because they lack the strong specializations
  • found in most other mammalian orders
  • We can, however, point to several trends
  • in their evolution that help define primates
  • and are related to their arboreal,
  • or tree-dwelling, ancestry

5
Trends in Primates
  • These include changes in the skeleton
  • and mode of locomotion,
  • an increase in brain size,
  • a shift toward smaller, fewer, and less
    specialized teeth,
  • the evolution of stereoscopic vision
  • and a grasping hand with opposable thumb
  • Not all these trends took place in every primate
    group,
  • nor did they evolve at the same rate in each group

6
Classification of Primates
  • The primate order is divided into two suborders
  • The prosimians, or lower primates,
  • include the lemurs, lorises, tarsiers, and tree
    shrews,
  • while the anthropoids, or higher primates,
  • include monkeys, apes, and humans

7
Prosimians
  • Prosimians are generally small,
  • ranging from species the size of a mouse
  • up to those as large as a house cat
  • They are arboreal, have five digits
  • on each hand and foot
  • with either claws or nails,
  • and are typically omnivorous
  • They have large, forwardly directed eyes
  • specialized for night vision,
  • hence most are nocturnal

8
Prosimians
  • As their name implies
  • pro means "before," and simian means "ape,
  • prosimians are the oldest primate lineage,
  • and their fossil record extends back to the
    Paleocene
  • During the Eocene prosimians were
  • abundant, diversified, and widespread
  • in North America, Europe, and Asia

9
Prosimians Are Tropical
  • By the Oligocene, hardly any prosimians
  • were left in the northern continents
  • as the once widespread Eocene populations
  • migrated south to the warmer latitudes
  • of Africa, Asia, and Southeast Asia
  • Presently, prosimians are found
  • only in the tropical regions
  • of Asia, India, Africa, and Madagascar

10
Anthropoids
  • Anthropoids evolved from a prosimian lineage
  • sometime during the Late Eocene,
  • and by the Oligocene
  • they were well established
  • Anthropoids are divided into three superfamilies

11
Classification of Primates
  • Order Primates
  • Suborder Prosimii (lower primates) Lemurs,
    lorises, tarsiers, tree shrews
  • Suborder Anthropoidea (Higher primates Monkeys,
    apes, humans
  • Superfamily Cercopithecoidea Macaque, baboon,
    proboscis monkey
  • Superfamily Ceboidea Howler, spider, and
    squirrel monkeys
  • Superfamily Hominoidea Apes, humans
  • Family Pongidae Chimpanzees, orangutans,
    gorillas
  • Family Hylobatidae Gibbons, siamangs
  • Family Hominidae Humans

12
Old World Monkey Attributes
  • Old World monkeys
  • superfamily Cercopithecoidea
  • are characterized by close-set,
  • downward-directed nostrils
  • like those of apes and humans
  • grasping hands,
  • and a nonprehensile tail
  • They include
  • the macaque,
  • baboon,
  • and proboscis monkey

13
Old World Monkeys Distribution
  • Present-day Old World monkeys
  • are distributed in the tropical regions
  • of Africa and Asia
  • and are thought to have evolved
  • from a primitive anthropoid ancestor,
  • such as Aegyptopithecus,
  • sometime during the Oligocene

14
New World Monkeys
  • New World monkeys
  • superfamily Ceboidea
  • are found only in Central and South America
  • They probably evolved from African monkeys
  • that migrated across the widening Atlantic
  • sometime during the Early Oligocene,
  • and they have continued evolving in isolation
  • to this present day

15
No Contact
  • No evidence exists of any prosimian
  • or other primitive primates
  • in Central or South America
  • nor of any contact with Old World monkeys
  • after the initial immigration from Africa
  • New World monkeys are characterized
  • by a prehensile tail, flattish face,
  • and widely separated nostrils
  • and include the howler, spider, and squirrel
    monkeys

16
Hominoids
  • Hominoids
  • superfamily Hominoidea
  • consist of three families
  • the great apes
  • family Pongidae
  • which includes chimpanzees, orangutans, and
    gorillas
  • the lesser apes
  • family Hylobatidae
  • which are gibbons and siamangs
  • and the hominids
  • family Hominidae
  • which are humans and their extinct ancestors

17
Hominoid Lineage
  • The hominoid lineage
  • diverged from Old World monkeys
  • sometime before the Miocene,
  • but exactly when is still being debated
  • It is generally accepted, however,
  • that hominoids evolved in Africa,
  • probably from the ancestral group
  • that included Aegyptopithecus

18
Climatic Shifts
  • Recall that beginning in the Late Eocene
  • the northward movement of the continents
  • resulted in pronounced climatic shifts
  • In Africa, Europe, Asia, and elsewhere,
  • a major cooling trend began,
  • and the tropical and subtropical rain forests
  • slowly began to change to a variety of mixed
    forests
  • separated by savannas and open grasslands
  • as temperatures and rainfall decreased

19
Apes Adapted
  • As the climate changed,
  • the primate populations also changed
  • Prosimians and monkeys became rare,
  • whereas hominoids diversified
  • in the newly forming environments
  • and became abundant
  • Ape populations became reproductively isolated
  • from each other within the various forests,
  • leading to adaptive radiation
  • and increased diversity among the hominoids

20
Migration of Animals Possible
  • During the Miocene,
  • Africa collided with Eurasia,
  • producing additional changes in the climate,
  • as well as providing opportunities
  • for migration of animals
  • between the two landmasses

21
Hominoid Relationships
  • Two apelike groups evolved during the Miocene
  • that ultimately gave rise to present-day
    hominoids
  • Although scientists still disagree
  • on the early evolutionary relationships among the
    hominoids,
  • fossil evidence and molecular DNA similarities
  • between modern hominoid families
  • is providing a clearer picture of the
    evolutionary pathways
  • and relationships among the hominoids

22
One of the Earliest Anthropoids
  • Skull of Aegyptopithecus zeuxis,
  • one of the earliest known anthropoids

23
Dryopithecines
  • The first group, the Dryopithecines,
  • evolved in Africa during the Miocene
  • and subsequently spread to Eurasia,
  • following the collision between the two
    continents
  • The dryopithecines were a varied group of
    hominoids
  • in size,
  • skeletal features,
  • and life-style

24
Proconsul
  • The best-known dryopithecine and perhaps
  • ancestor of all later hominoids
  • is Proconsul,
  • an ape-like fruit-eating animal
  • that led a quadrupedal arboreal existence,
  • with limited activity on the ground
  • The dryopithecines were very abundant
  • and diverse during the Miocene and Pliocene,
  • particularly in Africa

25
Sivapithecids
  • The second group, the Sivapithecids,
  • evolved in Africa during the Miocene
  • and then spread throughout Eurasia
  • The fossil remains of Sivapithecids
  • consist mostly of jaws, skulls, and isolated
    teeth
  • There are few body or limb bones known,
  • and thus we know little about their body anatomy

26
Sivapithecids Ate Harder Foods
  • All sivapithecids had powerful jaws and teeth
  • with thick enamel and flat chewing surfaces,
  • suggesting a diet of harder foods such as nuts
  • Based on various lines of evidence,
  • the Sivapithecids appear to be the ancestral
    stock
  • from which present-day orangutans evolved

27
Two Lineages
  • Although many pieces are still missing,
  • particularly during critical intervals
  • in the African hominoid fossil record,
  • molecular DNA as well as fossil evidence
    indicates
  • that the Dryopithecines, African apes, and
    hominids form a closely related lineage
  • The Sivapithecids and orangutans
  • form a different lineage that did not lead to
    humans

28
Hominids
  • The hominids (family Hominidae)
  • the primate family that includes present-day
    humans
  • and their extinct ancestors
  • have a fossil record extending back
  • to almost 7 million years
  • Several features distinguish them from other
    hominoids
  • Hominids are bipedal
  • that is, they have an upright posture,
  • which is indicated by several modifications in
    their skeleton

29
Comparison of Locomotion
  • Comparison between quadrupedal and bipedal
    locomotion
  • in gorillas and humans
  • In gorillas the ischium bone is long
  • and the entire pelvis is tilted toward the
    horizontal

30
Comparison of Locomotion
  • Comparison between quadrupedal and bipedal
    locomotion
  • in gorillas and humans
  • In humans the ischium bone is much shorter
  • and the pelvis is vertical

31
Larger Reorganized Brain
  • In addition, hominids show a trend
  • toward a large and internally reorganized brain
  • An increase in brain size and organization
  • is apparent in comparing the brains of
  • a New World Monkey

32
Other Distinguishing Features
  • Other features that distinguish hominids from
    other hominoids include
  • a reduced face
  • and reduced canine teeth,
  • omnivorous feeding,
  • increased manual dexterity,
  • and the use of sophisticated tools

33
Geologic Age Ranges
  • The geologic age ranges
  • for the commonly accepted species of hominids

34
Debates
  • Remember that although the fossil record
  • of hominid evolution is not complete,
  • what does exist is well documented
  • Furthermore, it is the interpretation of that
    fossil record
  • that precipitates the often vigorous
  • and sometimes acrimonious debates
  • concerning our evolutionary history

35
Oldest Hominid
  • Sahelan-thropus tchadensis,
  • the oldest known hominid,
  • nearly 7 million years old,
  • was discovered in 2002 in Chad

36
Oldest Hominid
  • Besides being the oldest hominid,
  • humans and their extinct ancestors,
  • Sahelanthropus tchadensis shows a mosaic
  • of primitive and advanced features
  • that has excited and puzzled paleoanthropologists
  • The small brain case and most of the teeth
  • (except the canines) are chimp-like
  • However, the nose, which is fairly flat,
  • and the prominent brow ridges
  • are features only seen, until now,
  • in the human genus Homo

37
Australopithecines
  • Australopithecine is a collective term
  • for all members of the genus Australopithecus
  • Currently, five species are recognized
  • A. anamensis,
  • A. afarensis,
  • A. africanus,
  • A. robustus,
  • and A. boisei

38
Lucy
  • A reconstruction of Lucys skeleton
  • by Owen Lovejoy
  • and his students at Kent State University, Ohio
  • Lucy is an 3.2-million-year-old
  • Australopithecus afarensis individual
  • whose fossil remains were discovered by Donald
    Johanson
  • This recon-struction
  • illustrates how adaptations in
  • Lucys hip, leg and foot
  • allowed a fully bipedal
  • means of locomotion

39
Lucy
40
Lucys Babyactually 3.3 MY old
View from back, shoulder blades
  • Fossil of A afarensis from Dikkia, Ethiopia
  • 3 yr old child, found in sandstone- died during
    flood?
  • Actually 100,000 yrs older than Lucy!
  • Most complete skeleton ever found!

Scientific American Dec 2006
41
Hominid Footprints
  • Preserved in volcanic ash at Laetoli, Tanzania
  • Discovered in 1978 by Mary Leakey,
  • these footprints proved hominids
  • were bipedal walkers at least 3.5 million years
    ago
  • The footprints of two adults and possibly those
    of a child
  • are clearly visible in this photograph

42
Brain Size of A. afarensis
  • A. afarensis had a brain size of 380450 cubic
    centimeters (cc),
  • larger than the 300400 cc
  • of a chimpanzee
  • but much smaller than that of present-day humans
    (1350 cc average)

43
Apelike Features
  • The skull of A. afarensis retained many apelike
    features,
  • including massive brow ridges
  • and a forward-jutting jaw,
  • but its teeth were intermediate
  • between those of apes and humans
  • The heavily enameled molars
  • were probably an adaptation to chewing fruits,
    seeds, and roots

44
Landscape with A. afarensis
  • Re-creation of a Pliocene landscape
  • showing members of
  • Australo-pithecus afarensis
  • gathering and eating
  • various fruits and seeds

45
Skull of A. africanus
  • 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

46
Not As Well Adapted for Bipedalism
  • It appears the limbs
  • of A. africanus may not have been
  • as well adapted for bipedalism
  • as those of A. afarensis

47
Robust Species
  • Both A. afarensis and A. africanus
  • differ markedly from the so-called robust species
  • A. boisei (2.61.0 million years ago)
  • and A. robustus (2.01.2 million years ago)
  • A. boisei was 1.21.4 m tall
  • and weighed between 34 and 49 kg
  • It had a powerful upper body,
  • a distinctive bony crest on the top of its skull,
  • a flat face, and the largest molars of any
    hominids

48
A. robustus Was a Vegetarian
  • A. robustus, in contrast,
  • was somewhat smaller (1.11.3 m tall)
  • and lighter (3240 kg)
  • It had a flat face, and the crown of its skull
  • had an elevated bony crest
  • that provided additional area
  • for the attachment of strong jaw muscles
  • Its broad flat molars indicated
  • A. robustus was a vegetarian

49
Australopithecus robustus Skull
  • The skull of Australopithecus robustus
  • This species had a massive jaw,
  • powerful chewing muscles,
  • and large broad flat chewing teeth
  • apparently used for grinding up coarse plant food

50
Separate Lineage
  • Most scientists accept the idea
  • that the robust australopithecines
  • form a separate lineage
  • from the other australopithecine
  • that went extinct 1 million years ago

51
The Human Lineage
  • Homo habilis
  • The earliest member of our own genus Homo
  • is Homo habilis,
  • which lived 2.5-1.6 million years ago
  • Its remains were first found at Olduvai Gorge,
  • but it is also known
  • from Kenya, Ethiopia, and South Africa
  • H. habilis evolved from the A. afarensis and A.
    africanus lineage
  • and coexisted with A. africanus
  • for about 200,000 years

52
Geologic Age Ranges
  • The geologic age ranges
  • for the commonly accepted species of hominids

53
Characteristics of Homo habilis
  • 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 only weighed 32-37 kg

54
Homo Erectus
  • In contrast to the australopithecines and H.
    habilis,
  • which are unknown outside Africa,
  • Homo erectus was a widely distributed species,
  • having migrated from Africa during the
    Pleistocene
  • Specimens have been found
  • not only in Africa
  • but also in Europe, India, China ("Peking Man"),
  • and Indonesia ("Java Man")

55
Survived in Asia Until About 100,000 Years Ago
  • 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

56
H. erectus Differed From Modern Humans
  • 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)

57
Size Similar to Humans
  • H. erectus's skull was thick-walled,
  • its face was massive,
  • it had prominent brow ridges,
  • and its teeth were slightly larger than those of
    present-day humans
  • H. erectus was comparable to size to modem
    humans,
  • standing between 1.6 and 1.8 m tall
  • and weighing between 53 and 63 kg

58
Skull of Homo erectus
  • A reconstruction of the skull of Homo erectus
  • a widely distributed species
  • whose remains have been found
  • in Africa, Europe, India, China, and Indonesia

59
H. erectus Was a Tool Maker
  • 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

60
Homo erectus Using Tools
  • Re-creation of a Pleistocene setting in Europe
  • in which members of Homo erectus are
  • using fire and stone tools

61
The "Out of Africa" View
  • Currently, a heated debate surrounds the
    transition
  • from H. erectus to our own species, Homo sapiens
  • Paleoanthropologists are split into two camps
  • On the one side are those who support
  • the "out of Africa" view
  • According to this camp, early modern humans
  • evolved from a single woman in Africa,
  • whose offspring then migrated from Africa,
  • perhaps as recently as 100,000 years ago
  • and populated Europe and Asia,
  • driving the earlier hominid populations to
    extinction

62
The "Multiregional" View
  • On the other side are those supporting the
    "multiregional" view
  • According to this hypothesis,
  • early modern humans did not have an isolated
    origin in Africa,
  • but rather established separate populations
    throughout Eurasia
  • Occasional contact and interbreeding
  • between these populations enabled our species to
    maintain its overall cohesiveness,
  • while still preserving the regional differences
  • in people we see today

63
Homo sapiens Evolved From H. erectus
  • Regardless of which theory turns out to be
    correct,
  • our species, H. sapiens
  • most certainly evolved from H. erectus

64
Neaderthals
  • Perhaps the most famous of all fossil humans are
    the Neanderthals,
  • who inhabited Europe and the Near East
  • from about 200,000 to 30,000 years ago
  • Some paleoanthropologists regard the Neanderthals
  • as a variety or subspecies of our own species
    (Homo sapiens neanderthalensis),
  • whereas others regard them as a separate species
    (Homo neanderthalensis)

65
Neanderthal Skull
  • Reconstructed Neanderthal skull
  • The Neanderthals were characterized
  • by prominent heavy brow ridges and weak chin

66
Cold Adapted
  • The Neanderthal body was
  • somewhat more massive
  • and heavily muscled
  • than ours,
  • with rather short lower limbs,
  • much like those
  • of other cold-adapted people of today

67
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

68
Took Care of Their Injured
  • The remains of Neanderthals
  • are found chiefly in caves
  • and hutlike rock shelters,
  • which also contain a variety
  • of specialized stone tools and weapons
  • Furthermore, archaeological evidence indicates
  • that Neanderthals commonly
  • took care of their injured and buried their dead,
  • frequently with such grave items
  • as tools, food, and perhaps even flowers

69
Cro-Magnons
  • About 30,000 years ago,
  • humans closely resembling modern Europeans
  • moved into the region inhabited
  • by the Neanderthals and completely replaced them
  • Cro-Magnons, the name given to
  • the successors of the Neanderthals in France,
  • lived from about 35,000 to 10,000 years ago
  • during this period the development of art and
    technology
  • far exceeded anything the world had seen before

70
Nomadic Hunters
  • Highly skilled nomadic hunters,
  • Cro-Magnons followed the herds
  • in their seasonal migrations
  • They used a variety of specialized tools
  • in their hunts, including perhaps the bow and
    arrow
  • They sought refuge in caves and rock shelters
  • and formed living groups of various sizes

71
Cave Painters
  • Cro-Magnons were also cave painters
  • Using paints made from manganese and iron oxides,
  • Cro-Magnon people painted hundreds of scenes
  • on the ceilings and walls of caves
  • in France and Spain,
  • where many of them are still preserved today

72
Painting From a Cave in France
  • Cro-Magnons were very skilled cave painters
  • Painting of a horse
  • from the cave of Niaux, France

73
Cultural Evolution
  • 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
  • Since the evolution of the Neanderthals
  • about 200,000 years ago,
  • humans have gone from a stone culture
  • to a technology that has allowed us
  • to visit other planets with space probes
  • and land astronauts on the Moon

74
Future
  • It remains to be seen
  • how we will use this technology in the future
  • and whether we will continue as a species,
  • evolve into another species,
  • or become extinct as many groups have before us

75
Summary
  • The primates evolved during the Paleocene
  • Several trends help characterize primate
  • and differentiate them from other mammalian
    orders,
  • including a change in overall skeletal structure
    and mode of locomotion
  • an increase in brain size
  • stereoscopic vision
  • and evolution of a grasping hand with opposable
    thumb

76
Summary
  • The primates are divided into two suborders
  • the prosimians and the anthropoids
  • The prosimians are the oldest primate lineage
  • and include lemurs, lorises, tarsiers, and tree
    shrews
  • The anthropoids include
  • the New and Old World monkeys,
  • apes,
  • and hominids, which are humans
  • and their extinct ancestors

77
Summary
  • The oldest known hominid is Sahelanthropus
    tchadensis,
  • dated at nearly 7 million years
  • then two subspecies of Ardipithecus at 5.8 and
    4.4 million years respectively
  • These early hominids were succeeded by the
    australopithecines
  • a fully bipedal group that evolved in Africa 4.2
    million years ago

78
Summary
  • Currently, five australopithecine species are
    known
  • Australopithecus anamensis, A. afarensis, A.
    africanus, A. robustus and A. boisei
  • The human lineage began
  • about 2.5 million years ago in Africa
  • with the evolution of Homo habilis,
  • which survived as a species
  • until about 1.6 million years ago
  • Homo erectus evolved from habilis
  • about 1.8 million years ago
  • and was the first hominid to migrate out of Africa

79
Summary
  • Between 1 and 1.8 million years ago, H. erectus
  • had spread to Europe, India, China, and Indonesia
  • H. erectus used fire, made tools, and lived in
    caves
  • Sometime between 200,000 and 100,000 years ago
  • Homo Sapiens evolved from H. erectus
  • These early humans may be ancestors of Neaderthals

80
Summary
  • Neanderthals were not much different
  • from present-day humans,
  • only more robust
  • and with differently shaped skulls
  • They made specialized tools and weapons,
  • apparently took care of their injured,
  • and buried their dead
  • The Cro-Magnons were the successors
  • of the Neanderthals
  • and lived from about 35,000-10,000 years ago

81
Summary
  • Cro-Magnons were highly skilled nomadic hunters,
  • formed living groups of various sizes,
  • and were also skilled cave painters
  • Modern humans succeeded the Cro-Magnons
  • about 10,000 years ago
  • and have spread throughout the world

82
New Hypotheses About Our Ancestry
  • In this section we examine the various primate
    groups,
  • in particular the origin and evolution of the
    hominids,
  • the group that includes our ancestors
  • However, we must point out
  • that new discoveries of fossil hominids,
  • as well as new techniques for scientific analysis
  • are leading to new hypotheses about our ancestry

83
Exciting Study
  • Even as we speak, therefore,
  • new discoveries may have changed
  • some of our conclusions
  • based on what we currently know
  • Such is the nature of paleoanthropology
  • and one reason why the study of hominids
  • is so exciting

84
Variations
  • In fact, some primates
  • have retained certain primitive features,
  • whereas others show all
  • or most of these trends

85
Classification of Primates
  • Order Primates
  • Suborder Prosimii (lower primates) Lemurs,
    lorises, tarsiers, tree shrews
  • Suborder Anthropoidea (Higher primates) Monkeys,
    apes, humans
  • Superfamily Cercopithecoidea Macaque, baboon,
    proboscis monkey
  • Superfamily Ceboidea Howler, spider, and
    squirrel monkeys
  • Superfamily Hominoidea Apes, humans
  • Family Pongidae Chimpanzees, orangutans,
    gorillas
  • Family Hylobatidae Gibbons, siamangs
  • Family Hominidae Humans

86
Larger Reorganized Brain
  • In addition, hominids show a trend
  • toward a large and internally reorganized brain
  • An increase in brain size and organization
  • is apparent in comparing the brains of
  • a great ape

87
Larger Reorganized Brain
  • In addition, hominids show a trend
  • toward a large and internally reorganized brain
  • An increase in brain size and organization
  • is apparent in comparing the brains of
  • a present-day human

88
Ring-Tailed Lemur
  • Ring-Tailed Lemur are also prosimians

89
New World Monkey
  • New World Monkeys constitute a superfamily
    belonging to the suborder Anthropoidea
    (anthropoids)

90
Old Word Monkey
  • Another superfamily of the anthropoids
  • the Old World monkeys

91
Chimpanzee
  • Chimpanzees

92
Early History of Anthropoids
  • Much of our knowledge about
  • the early evolutionary history of anthropoids
  • comes from fossils found in the Fayum district,
  • a small desert area southwest of Cairo, Egypt
  • During the Late Eocene and Oligocene,
  • this region of Africa was a lush, tropical rain
    forest
  • that supported a diverse and abundant fauna and
    flora
  • Within this forest lived many different
  • arboreal anthropoids as well as various prosimians

93
Thousands of Fossil Specimens
  • In fact, several thousand fossil specimens
  • representing more than 20 species of primates
  • have been recovered from rocks of this region
  • One of the earliest anthropoids,
  • and a possible ancestor of the Old World monkeys,
  • was Aegyptopithecus,
  • a small, fruit-eating, arboreal primate
  • that weighed about 5 kg

94
Response to Climatic Changes
  • Many anthropologists think
  • these hominid features evolved in response
  • to major climatic changes
  • that began during the Miocene
  • and continued into the Pliocene
  • During this time, vast savannas
  • replaced the African tropical rain forests
  • where the lower primates
  • and Old World monkeys had been so abundant

95
Mixed Forests and Grasslands
  • As the savannas and grasslands
  • continued to expand,
  • the hominids made the transition
  • from true forest dwelling
  • to life to an environment
  • of mixed forests and grasslands

96
No Clear Consensus
  • At present, no clear consensus exists
  • on the evolutionary history of the hominid
    lineage
  • This is due in part
  • to the incomplete fossil record of hominids
  • as well as new discoveries,
  • and also because some species
  • are known only from partial specimens
  • or fragments of bone
  • Because of this, scientists even disagree
  • on the total number of hominid species

97
Some Current Theories
  • A complete discussion
  • of all the proposed hominid species
  • and the various competing schemes of hominid
    evolution
  • is beyond the scope of this course
  • However, we will discuss the generally accepted
    taxa
  • and present some of the current theories
  • of hominid evolution

98
Evolutionary Scheme
  • Many paleontologists accept
  • the evolutionary scheme in which
  • 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

99
Oldest Known Australopithecine
  • The oldest known australopithecine
  • is Australopithecus anamensis
  • and was discovered at Kanapoi,
  • a site near Lake Turkana, Kenya,
  • by Meave Leakey
  • of the National Museums of Kenya
  • and her colleagues

100
Similar Yet More Primitive
  • A. anamensis, a 4.2-million-year-old bipedal
    species,
  • has many features in common
  • with its younger relative, A. afarensis,
  • yet is more primitive in other characteristics,
  • such as its teeth and skull
  • A. anamensis
  • is estimated to have been
  • between 1.3 and 1.5 m tall
  • and weighed between 33 and 50 kg

101
Australopithecus afarensis
  • Australopithecus afarensis,
  • which lived 3.93.0 million years ago,
  • was fully bipedal
  • and exhibited great variability in size and
    weight
  • Members of this species ranged
  • from just over 1 m to about 1.5 m tall
  • and weighed between 29 and 45 kg

102
Hominid Footprints
  • Most scientists think the footprints
  • were made by Australopithecus afarensis
  • whose fossils are found at Laetoli

103
A. africanus Lived 3.02.3 mya
  • A. afarensis was succeeded by
  • Australopithecus africanus,
  • which lived 3.02.3 million years ago
  • The differences between the two species are
    relatively minor
  • They were both about the same size and weight,
  • but A. africanus had a flatter face
  • and somewhat larger brain

104
Specimens Found in Neander Valley
  • In any case, their name comes
  • from the first specimens found in 1856
  • in the Neander Valley near Düsseldorf, Germany

105
Neanderthals Difference
  • The most notable difference between Neanderthals
  • and present-day humans is in the skull
  • Neanderthal skulls were long and low
  • with 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

106
First Humans in Cold Climates
  • 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 country

107
Understanding in Flux
  • So where does this leave us, evolutionarily
    speaking?
  • At a very exciting time as we seek to unravel the
    history of our species
  • Our understanding of our genealogy
  • is presently in flux,
  • and each new fossil hominid find
  • sheds more light on our ancestry

108
Human Evolution
  • Apparently human evolution
  • is just like that of other groups
  • Just as with non-hominid predecessors,
  • our ancestors followed an uncertain path
  • As new species evolved,
  • they filled ecologic niches
  • and either gave rise to descendants
  • better adapted to the changing environment
  • or became extinct

109
Continuing Discoveries Change Our Ideas
  • As recently as 2000,
  • the earliest fossil evidence of hominids
  • was from 4.4-million-year-old rocks in eastern
    Africa
  • Since then, as just noted, discoveries have
    pushed
  • that age back to almost 7 million years

110
Anthropoid Superfamilies
  • Anthropoids are divided into three superfamilies
  • Old World monkeys,
  • New World monkeys,
  • and hominoids

111
Next Oldest Hominid
  • The next oldest hominid is Orrorin tugenensis,
  • whose fossils have been dated at six million
    years
  • and consist of bits of jaw, isolated teeth,
  • finger, arm, and partial upper leg bones
  • At this time, debate continues
  • as to exactly where Orrorin tugenensis fits in
    the hominid lineage

112
Ardipithecus ramidus
  • Sometime between 5.8 and 5.2 million years ago,
  • another hominid was present in eastern Africa
  • Ardipithecus ramidus kadabba is older
  • than its 4.4 million year old relative
  • Ardipithecus ramidus ramidus
  • Ardipithecus ramidus kadabba is very similar
  • in most features to Ardipithecus ramidus ramidus
  • but in certain features of its teeth
  • is more apelike than its younger relative

113
Geologic Age Ranges
  • The geologic age ranges
  • for the commonly accepted species of hominids

114
Bushy Model of Human Evolution
  • For instance, paleoanthropologists now think
  • that human evolution branched many times
  • rather than evolving in a somewhat straight line
  • leading to modern humans
  • According to this bushy model
  • of human evolution,
  • such key traits as
  • upright walking,
  • manual dexterity
  • and a large brain
  • evolved more than once,
  • and produced many evolutionary dead-ends

115
When Humans and Chimpanzees Diverged
  • Presently, most paleoanthropologists accept
  • that the human-chimpanzee stock separated
  • from gorillas about 8 million years ago
  • and humans separated from chimpanzees
  • about 5 million years ago
  • Thus Sahelanthropus tchadensis is
  • at or near the point in time
  • when humans and chimpanzees diverged

116
Oldest Known Hominid
  • Discovered in northern Chad's Djurab Desert
  • in July, 2002,
  • the nearly 7-million-year-old skull
  • and dental remains of Sahelanthropus tchadensis
  • make it the oldest known hominid yet unearthed
  • and very close to the time
  • when humans diverged
  • from our closest-living relative, the chimpanzee

117
Habitual Bipedal Walkers
  • Although many paleoanthropologists think
  • both Orrorin tugenensis and Ardipithecus ramidus
    kadabba
  • were habitual bipedal walkers
  • and thus on a direct evolutionary line to humans,
  • others are not as impressed with the fossil
    evidence
  • and are reserving judgment
  • Until more fossil evidence is found and analyzed,
  • any single scheme of hominid evolution presented
    here would be premature

118
Global Climatic Cycles in Geologic Time
from L E Waite (2002), modified from Fischer
(1984)
119
Temperature change last 2000 years
http//dels.nas.edu/dels/rpt_briefs/Surface_Temps_
final.pdf
120
Temperature change _at_ different time scales
Glacial and Interglacial Periods
http//dels.nas.edu/basc/Climate-LOW.pdf
121
Leg Bones and Feet Needed
  • Sahelanthropus tchadensis may have been
  • bipedal in its walking habits,
  • but until bones from its legs and feet are found,
  • that supposition remains conjecture

122
Tarsier
  • Tarsiers are prosimian primates

123
Eocene Prosimian
  • Notharctus, a primitive Eocene prosimian
  • from North America

124
Prosimians Declined in Cooler Climate
  • As the continents moved northward
  • during the Cenozoic
  • and the climate changed from warm tropical
  • to cooler mid-latitude conditions,
  • the prosimian population decreased
  • in both abundance and diversity

125
Old Word Monkey
  • Superfamily Cercopithecoidea
  • the Old World monkeys

126
New World Monkey
  • New World Monkeys are members of the superfamily
    Ceboidea

127
Great Apes
  • The third superfamily is the great apes,
  • which include Gorillas and...

128
Proconsul
  • Probable appearance of Proconsul, a dryopithecine

129
Hope of Life
  • In fact, a skull found in the African nation of
    Chad,
  • in 2002 and named Sahelanthropus tchadensis
  • but nicknamed Tourmaï,
  • which means "hope of life"
  • in the local Goran language,
  • has pushed back the origins of humans
  • to nearly 7 million years ago
  • Instead of simplifying our ancestry, however,
  • its discovery has raised more questions
  • than it answered

130
Cro-Magnon Camp
  • Re-creation of a Cro-Magnon camp in Europe
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