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Hominid

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Title: Hominid


1
Hominid EvolutionOn The Origin of Humans
2
What is a Hominid?
  • The term hominid is also used in the more
    restricted sense as hominins
  • Humans and relatives of humans closer than
    chimpanzees
  • Bipedal
  • Modern man is the only member of this group alive
    today

3
Hominid Sites
  • Earliest fossil hominid sites are in Africa
  • They now span the latest Miocene to the early
    Pleistocene from about 6-7 mya to about 1.6 mya
  • The major groups of sites are
  1. Ethiopia Middle Awash valley Hadar
    (Australopithecus afarensis)
  2. Kenya Lake Turkana
  3. Tanzania Olduvai Gorge
  4. South Africa various sites in limestone caverns
    centered around Sterkfontein

4
What Makes A Hominid? - Bipedalism
  • Primary feature distinguishing hominids from
    other hominoids is walking erect on two legs
    erect bipedalism
  • Adaptations for bipedalism in the partial
    skeleton of Lucy, an australopithecine ( 3.2
    mya) clearly seen in the hip, spine and leg bones

5
Why did bipedalism become the primary adaptation
of hominids?
  • Climate Change resulting in forest habitat being
    replaced
  • by grasslands.

6
Advantages of Bipedalism
  • 1. Carrying behavior
  • 2. Reduction of overall heat stress -
    facilitates heat loss through convection by
    exposing body to air currents, only humans have
    sweat glands that produce moisture to cool body
  • 3. Most energy efficient way to travel long
    distances
  • 4. Allows for better vision in open
    environments defensive action against predators
    by freeing hands to throw objects

7
Evidence for Early Bipedalism
  • The record of bipedalism is most graphically
    preserved in the fossilized footprints at
    Laetoli, Tanzania, 3.6 mya
  • Tracks of 2 individuals were uncovered in
    volcanic ash by Mary Leakey (1978-79)
  • Footprints were left by 2 australopithecines in
    damp volcanic ash of Laetoli
  • Notice how close the tracks are!

8
Laetoli Footprints
  • Laetoli footprints clearly show that the
    creatures who made them were fully bipedal
  • Big toe hardly diverges from the rest of the
    foot, unlike in apes
  • Gait heel-strike followed by toe-off the
    way modern humans walk

9
Laetoli Reconstruction
  • 2 early hominids walk bipedally across an open
    ash field produced by an erupting volcano.
  • Rain wet the volcanic ash footprints filled up
    with more ash, and were thus preserved.
  • Footprints reveal that our ancestors walked
    upright with a gait very similar to our own.

10
First Adaptive Radiation
  • 7-6 mya in the late Miocene, potential last
    common ancestors between humans and apes
  • 1. Sahelanthropus tchadensis
  • 7-6 mya in Chad (North Central Africa)
  • 2. Orrorin tungenensis
  • 6 mya in Kenya (East Africa)
  • Note These organisms were forest adapted.

11
1. Sahelanthropus tchadensis
  • Discovered in Chad (7-6 mya)
  • Most complete cranium from this time period
  • Mosaic of ape human-like features, but at the
    ape grade of evolution
  • Cranial capacity (320-380 cc)
  • U-shaped upper jaw
  • Very wide distance between the orbits
  • Large, thick continuous brow ridge
  • Human-like flat face
  • Human-like dentition

12
2. Orrorin tungenensis
  • Fossils from Tugen Hills in Kenya have been
    dated to about 6 mya
  • Earliest Evidence for
  • Walking on Two Legs?

13
Orrorin tungenensis (cont.)
  • Fossils Include upper portion of a femur, lower
    portion of the humerus, some lower jaw fragments,
    teeth
  • Arm bone virtually identical to that of a
    chimpanzee
  • Femur more human-like, most important for
    showing adaptations for walking on 2 legs
  • Was Orrorin a direct human ancestor, or a
    common ancestor of chimps and humans?

14
Second Adaptive Radiation
  • 5-4 mya in early Pliocene, first true hominids
  • 1. Ardipithecus ramidus
  • 5.5-4.5 mya in Ethiopia (East Africa)
  • 2. Australopithecus anamensis
  • 4.2-3.9 mya in Kenya (East Africa)
  • Note These organisms were forest adapted and
    fully bipedal.

15
1. Ardipithecus ramidus
Earliest True Hominid or Last Common
Ancestor? LAST COMMON ANCESTOR OF CHIMPS HUMANS
MOST LIKELY HAD A MIX OF FEATURES SOME RETAINED
IN CHIMPS, OTHERS RETAINED IN HUMANS!
16
Ardipithecus ramidus (cont.)
  • Between 4.5 and 5.5 mya from the Middle Awash
    valley site in Ethiopia
  • Fossil Remains very fragmentary limb bones, toe
    bones, jaws teeth
  • Straight toe bones suggest it may have been
    bipedal
  • A mosaic of features seen in later hominids
    modern chimpanzees

17
2. Australopithecus anamensis
  • Lake Turkana Region of Kenya
  • 4.2-3.9 mya
  • Probably walked upright
  • Teeth enamel thicker than Ardipithecus ramidus,
    so diet included hard foods

18
Australopithecus anamensis (cont.)
  • Fossil Remains very fragmentary
  • Those shown here include
  • Jawbone
  • part of the front of the face
  • parts of an arm bone (radius)
  • fragments of a lower leg bone (tibia)

19
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20
Third Adaptive Radiation
  • 4-3 mya in middle Pliocene, many hominids
  • 1. Australopithecus afarensis (Lucy)
  • 4-3 mya in East Africa
  • 2. Australopithecus africanus
  • 4-2.5 mya in South Africa
  • 3. Kenyanthropus platyops
  • 3.5-3.2 mya in Kenya
  • Note These organisms lived in open woodlands
    along wooded streams in the savannas, ate fruits
    and soft foods, maybe had a tool-culture like
    modern chimps

21
1. Australopithecus afarensis
  • 4-3 mya in East Africa
  • Pelvis leg bones resemble modern humans
  • Sexual dimorphism (males larger with sagittal
    crest)
  • Tree climbers (curved fingers toes)
  • Ape-like Features
  • Small brain case (430 cc.)
  • Prognathic (jutting out) face
  • U-shaped palate (v. parabolic shape)

22
Australopithecus afarensis
23
A. afarensis Skeleton - Lucy
24
2. Australopithecus africanus
  • 4-2.5 mya in Transvaal region of South Africa
  • 1924 1st Australopithicine to be described by
    Raymond Dart!
  • Globular cranium, slightly higher ratio of brain
    to body size than A. afarensis
  • Face less prognathic than A. afarensis
  • Proportions of arm to leg lengths may be more
    ape-like than A. afarensis

25
Australopithecus africanus
Australopithecus africanus
best known A. africanus cranium (front lateral
views)
Most complete A. africanus skull
Taung Child
26
A. afarensis
A. afarensis verses A. africanus
Australopithecus afarensis
Australopithecus africanus
27
3. Kenyanthropus platyops
  • 3.5-3.2 mya found in 2001 west of Lake Turkana
    in Kenya
  • Ape-like features small ear canal, small brain
    case
  • Human-like features flat face, small molars
  • Importance flat face appeared early in
    evolution, alongside the range of other facial
    forms. Evidence that evolution is not linear or
    progressive.

28
Kenyanthropus platyops
29
Fourth Adaptive Radiation
  • 3-1 mya in late Pliocene, more robust hominids
  • 1. Paranthropus boisei
  • 2.2-1.2 mya in East Africa
  • 2. Paranthropus robustus
  • 2-1 mya in South Africa
  • 3. Australopithecus garhi
  • 3-2 mya in East Africa
  • Note Lived in open dry woodlands savannas.
    The robust species are famous for eating hard-to-
    chew food, like seeds, nuts, and roots. May have
    used tools to dig for roots in dry seasons.

30
1. Paranthropus boisei
  • 2.2-1.2 mya in East Africa Ethiopia, Kenya,
    Tanzania
  • Largest teeth found in any hominid!
  • Referred to as hyper-robust due to massive
    molars and premolars
  • Skull broad, short face with flaring cheek
    bones, relatively small brain, pronounced
    sagittal crest in males
  • Skull and dental features are adaptations for
    heavy chewing!

31
Paranthropus boisei (KNM-ER 406)
32
Paranthropus boisei (KNM-ER 406)
33
2. Paranthropus robustus
  • 2-1 mya in South Africa
  • Short, broad face with deep zygomatic arches
    (cheek bones). Larger individuals have sagittal
    crests.
  • Large molars covered with thick enamel
  • Wear patterns on teeth herbivorous diet of hard
    resistant foods such as seeds, nuts, roots
  • Lived in grasslands near rivers and wetlands

34
Paranthropus robustus
35
3. Australopithecus garhi
  • 3-2 mya in East Africa spotty fossil record,
    cranial dental remains found in 1999 in Bouri,
    Ethiopia
  • Bones of antelopes, horses, and other animals
    with cut marks made by stone tools butchering
    animals smashing bones for marrow. First meat
    eaters?
  • Molars too large to be early Homo genus
  • Ape-like long lower arm, human-like upper arm
    leg
  • Mixed traits classified as a new species, maybe
    ancestor of early Homo genus

36
Australopithecus garhi
37
Australopithecus garhi
One surprise in the A. garhi skull was enormous
back teeth, instead of smaller ones seen in later
Homo species
38
Australopithecus garhi
  • EARLIEST BUTCHERS
  • Signs that hominids scraped smashed animal
    bones, like this antelope tibia, 2.5 mya
  • Earliest documented percussion marks made by
    hominids, presumably extracting fatty marrow from
    these bones

39
Rise of the Genus Homo
  • Homo habilis Handy Man
  • Homo erectus or Homo ergaster in Africa
  • Homo heidelbergensis Archaic Homo sapiens
  • Homo sapiens neanderthalensis - Neanderthal
  • Homo sapiens sapiens Modern Man

40
Homo habilis
2.4 1.4 MYA
  • Slightly larger braincase and smaller face and
    teeth than Australopithecus
  • Still retains ape-like features of long arms and
    moderately prognathic face
  • Average height 34 to 45
  • Average weight 70 lbs.

41
Homo habilis
  • Thick tooth enamel suggests they had an
    omnivorous diet, but were capable of eating
    fairly tough foods like leaves and woody plants

By this time, the feet of early humans had a
modern-type arch
42
Homo erectus
1.89 MYA 143,000 years ago
  • Modern human-like body proportions indicate
    adaptations for living exclusively on the ground
  • Expanded braincase relative to the size of the
    face
  • Left Africa and spread into Asia
  • Longest lived early human relative (9 times
    longer than we have been around so far)
  • Used fire (warmth, cooking)
  • Evidence they cared for the sick and old (see
    skull to left)
  • Average height 49 to 61
  • Average weight 88-150 lbs.

43
Homo erectus
Turkana boy fossil
Hand axe first major innovation in stone tool
technology
44
Homo heidelbergensis
  • Very large brow ridge
  • Larger braincase and flatter face than earlier
    human ancestors
  • Short, wide bodies adapted to living in colder
    climates
  • Most likely candidate to have been common
    ancestor between Neanderthals and modern humans
  • Average height males 59, females 52
  • Average weight males 136 lbs., females 112 lbs.

700,00 200,00 years ago
45
Homo heidelbergensis
  • Used wooden spears to routinely hunt large
    animals
  • Built shelters out of wood and rock

46
Homo sapiens neanderthalensis
  • Short, stocky bodies and huge noses were
    adaptations for living in cold environment
  • Larger braincase than modern man
  • Sophisticated tools, used shelters, wore clothing
  • First human ancestor to bury their dead and mark
    the graves
  • Modern humans led to their extinction but unclear
    as to exactly how
  • Average height males 55, females 51
  • Average weight males 143 lbs., females 119 lbs.

200,000 28,000 years ago
47
Homo sapiens neanderthalensis
Ornamental jewlery
La Ferrassie 1 Most complete Neanderthal skull
ever found
48
Homo sapiens sapiens
  • Originated in Africa 200,000 years ago
  • Highly vaulted, thin-walled skull led to more
    developed frontal lobe of brain
  • Flat forehead and face
  • Less heavily developed jaws and small teeth

49
Homo sapiens sapiens
50
Homo sapiens sapiens
Many advancements in art, culture and tool making
technology
51
Map of Hominid Evolution
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