Hominid Evolution

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Hominid Evolution
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Early Primates

• Prosimians (65mya)
• Monkeys (35mya)
• Apes (23mya)
• Hominids (5mya)

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Early Primate Traits

• Common physical primate traits
• Dense hair or fur covering
• Warm-blooded
• Live young
• Suckle
• Infant dependence
• Common social primate traits
• Social life
• Play
• Observation and imitation
• Pecking order

Common Primate Traits
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Primate Family Tree
Orangutan
Crown lemur
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1. Australopithecus afarensis Cranium
2. Australopithecus africanus Cranium
3. Homo habilis Cranium
4. Homo erectus Cranium
5. Neandertal Cranium
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Hominid Evolution
Gorilla Pan Homo
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What features distinguish humans from the other
apes?
Gorilla Pan Homo
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Some major characteristics of hominid evolution

• Jaw shape
• Bipedal posture
• Reduced size difference between the sexes
• Brain size
• Family structure

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1400
Range
1200
In the course of hominid evolution, there is
an increase in brain volume
1000
800
600
Brain volume (cm3)
400
200
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Homo neanderthalensis
Homo habilis
Homo erectus
Australopithecus
Homo sapiens
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In the course of primate evolution, there has
been a trend toward longer periods of juvenile
dependency
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Two main groups of hominids
Homo (2.5 mya)
Australopithecines (4 mya) (Australopithecus,
Paranthropus)
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Australopithecus



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Australopithecines are divided into two groups
A. boisei
A. africanus
Gracile small boned ape-like forms (A.
africanus, A. afarensis)
Robust ape-like forms (A. boisei, A. robustus)
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Skull specialized for heavy chewing
large cheek teeth large jaw robust zygomatic
arches prominent saggital crest
A. robustus
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Skull morphology suggests a more generalized
approach to food
smaller molars absence of bony crests for heavy
chewing
A. africanus
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Australopithecus africanus 3 2.3 mya

• Discovered in 1924 by Raymond Dart
• in S. Africa
• Probably walked fully erect
• Humanlike hands and teeth
• The brain was only about
• 1/3 the size of modern
• humans brain

Taung Child
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Were human ancestors hunted by birds? Research
provides a break in the case of a famous
hominids death
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Australopithecus afarensis 4 - 2.7 mya
Afar region of Ethiopia (Donald Johansen,
1974) Lucy complete skeleton of adult
female Diet Soft fruit, nuts, seeds, tubers and
bird eggs. Size M 152cm / 45kg F 107cm / 28
kg.
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Upright posture predates an enlarged brain in
human evolution
3.5 my old Hominin footprints in the volcanic
ash in Laetoli, Tanzania
Lucy skeleton
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paleoanthropologists have found hominid species
that predate A. afarensis
1994 A. anamensis was discovered by Maeve Leakey
in Kenya Lived just over 4.2 3.9
mya Found Upper/lower jaws Cranial
fragments Upper and lower parts of leg bone
1995, Ardipithecus (possibly predates A.
afarensis) 2001, Kenyanthropus platyops (3.5
3.2 mya)
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Australopithecus anamensis
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Australopithecus garhi
Discovered 1996 Berhane Asfaw Tim
White Ethiopia Afar Basin Garhi means surprise
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Prehominid Evolution

• Ardipithecus ramidus 4.4 - ? mya
• A. anamensis 4.2 - 3.9
• A. afarensis 4.2 - 2.5
• A. bahrelghazali 3.5 - 3.0
• A. africanus 3.5 - 2.5
• P. aethiopicus 2.7 - 2.3
• A. garhi 2.5 - ?
• P. boisei 2.3 - 1.3
• P. robustus 2.0 - 1.0

Reconstruction of Australopithecine
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Why Bipedalism?
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Evolution of Bipedalism

• Anatomical changes
• Neck (1), chest (2), lower back (3), hips and
  pelvis (4), thighs (5), knees (6), feet (7)
• Theories
• Tool use and bipedalism (Darwin/Washburn)
• Energy efficiency and bipedalism (Isbell/Young)
• Body temperature and bipedalism (Wheeler)
• Habitat variability and bipedalism (Potts)
• Reproduction and bipedalism (Lovejoy)
• Canine reduction and bipedalism (Jolly)

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Muscle Functions Gluteus maximus Straightens
supports the hip joint involved in
walking Gluteus medius Rotate balance the
trunk over the single supporting limb
foot Quadruceps femoris extend straighten the
knee joint
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Femur not angled in quadrupeds
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Ardipithecus ramidus
Discovered by Tim White 1995 Oldest known
hominid (about 4.4 million years ago) Fragments
of skull remains and skeleton found in the Afar
Depression in Ethiopia ramid root (Afar),
ardipithecus ground, floor (Afar) Possibly
bipedal Heavily forested, flood plain environment
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Which of the australopithecines were
evolutionary dead ends and which were close to
or on the lineage that eventually sprouted the
Homo branch?
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evolutionary dead end?
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Australopithecus aethiopicus

• 2.5 mya
• Found in 1985 by Richard Leaky
• Alan Walker
• Lake Turkana in Northern Tanzania
• Commonly called the black skull

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Australopithecus boisei
Discovered 1959 Mary Leakey East Africa at the
Olduvai Gorge in Tanzania Also found in Ethiopia
and Kenya Lived 2.6 - 1.2 mya Called
Zinjanthropus boisei, but later changed to
Australopithecus boisei. Often referred to as
Paranthropus boisei
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Australopithecus robustus

• Discovered 1938
• - Robert Broom
• Often referred to as Paranthropus robustus
• Lived 2-1 mya

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And nowthe Hominids
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The earliest fossils that anthropologists place
in Homo are classified as Homo habilis

• Discovered by the Mary Louis Leaky in 1964
• Existed from 2.5 1.6 mya in E. Africa
• Teeth were smaller and the brain was
• significantly larger
• 5 feet tall 100 lbs average
• Less prognathic jaws and larger brains
• than australopithecines
• Sharp stone tools have been found with
• these fossils (Oldowan tools)

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Homo habilis

• 612 cc brain
• 2.3 - 1.6 mya
• first toolmaker
• prognathic face, brow ridge
• probable meat-eater
• possibly arboreal
• discovered in 1960 by Leakeys
• no speech

Artists representation of a Homo habilis band as
it might have existed two million years ago.
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Oldowan tools
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H. habilis v. H. erectus

• Finds in east Africa indicate that Homo habilis
  was not very different from the
  australopithecines in terms of body size and
  shape.
• The earliest Homo erectus remains indicate rapid
  biological change.
• The fossil record for the transition from H.
  habilis to H. erectus supports the punctuated
  equilibrium model of evolution.
• H. erectus was considerably taller and had a
  larger brain than H. habilis.

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Anatomical characters unique in Homo

• An increase in cranial vault height and thickness
  
• Reduced lower facial prognathism
• Reduction in the size of premolars and molars and
  the length of the molar row
• Increase in brain size

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Homo erectus was the first hominid to migrate
out of Africa

• Lived from 1.8 mya 500,000 ya
• Discovered by Eugene Dubois in 1891
• Fossils from Asia are known as
• Beijing man and Java Man
• Compared to H. habilis, H. erectus
• was taller, had a larger brain,
• and were less sexually dimorphic

Nature, 2002
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Homo erectus

• 1891 - Eugene Dubois discovers H. erectus in Java
• Dubois calls it Pithecanthropus erectus
  initially, also dubbed Java Man
• finds in China called Sinanthropus
• dates from 1.9 mya to 27,000 years B.P.
• 994 cc brain size (compare to 612 for H. habilis)
• Acheulean tool industry

Photograph of Nariokotome boy, an early Homo
erectus found near Lake Turkana, Kenya.
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Homo erectus 1.9mya to 27k yBP

• Why was H. erectus so successful?
• Less sexual dimorphism possible pair bonds,
  marriage
• Less hair on body wearing of furs, other
  clothing
• Wearing of furs ability to live further north

• Quick adaptation to environment without physical
  changes
• Culture is main reason H. erectus was so
  successful
• organization for hunting
• ability to protect against predators
• control of fire?
• possible campsites
• tools (Acheulean industry)

Distribution of H. erectus
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Homo erectus
Most fossils found in the Lake Turkana region of
northern Kenya
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trends linking erectus with sapiens includes

• An increase in brain size (erectus approximately
  900 cc., sapiens approximately 1350 cc.)
• A reduction in postcanine dentition, and a
  correlated decrease in jaw size
• Vertical shortening of the face
• Shortening of arm-bones (especially the forearm)
  to come to a very humanlike limb proportions
• The development of a more barrel-shaped chest.
• The formation of an external nose.
• Reached modern human size in terms of height.

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Homo Erectus

• 1st to control use of fire which lead to
• Better health
• Better hunting
• Warmth in colder climates

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In Europe Homo erectus gave rise to the
Neanderthals
Neanderthals (200,000 - 30,000 ya) settled
throughout Europe, Middle East, and parts of N.
Africa
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When and where did anatomically modern humans
originate?
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Figure 34.41 Two hypotheses for the origin of
anatomically modern humans
(emerge btwn. 160,000-154,000 ya,)
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Multiregional vs Out of Africa

• How exactly hominids spread into the rest of the
  world from Africa, is still unknown. The two
  possible theories for this occurrence are
  discussed in more detail in The Multiregional
  Hypothesis and the "Out of Africa" Hypothesis.
• Multiregionalism defends the side that represents
  no single origin for modern humanity, whereas the
  "Out of Africa" hypothesis states that humans
  originated in Africa and then slowly developed
  their modern forms in every area of the Old World
  some 200,000 years ago.

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How are Neanderthals related to us
If Neanderthals and Cro Magnons encountered one
another in Europe (30,000 ya), and they
interbred, Neanderthal MtDNA Sequences would
have entered the modern human gene pool. There
is no genetic evidence of interbreeding.
Genetic studies have shown that we are
genetically distinct from Neanderthals
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How are Neanderthals related to us
Anatomical evidence corroborates the genetic
results that Neanderthals did not contribute to
the ancestry of modern Europeans MtDNA
sequence variation supports single-origin theory
of modern human evolution Fossil evidence
indicates modern human morphology emerged in
Africa long before the Neanderthals vanished
from Eurasia
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Homo neanderthalensis

• discovered in the Neander Valley (Tal) near
  Dusseldorf, 1856
• massive brain--about 1,400cc on average
• large torso, short limbs, broad nasal passages
• later remains show decrease in robustness of the
  front teeth and face, suggesting use of tools
  replaced teeth
• mid-facial prognathism

The skull of the classic Neandertal found in 1908
at La Chapelle-aux-Saints.
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Neandertal Culture

• Homesites In caves, also in the open (near
  rivers, framed with wood and covered with skins)
• Burial Is there evidence of purposeful burial
  and ritual?
• Language Could Neandertals talk or not?
• Tools Mousterian tradition

Top Reconstruction of Neandertal burial from
Shanidar cave Bottom Mousterian tools
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Neanderthals vs Cro Magnons
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Homo sapiens

• Archaic 100,000 to 35,000 years BP
• Sometimes called Homo sapiens and Homo sapiens
  neanderthalensis
• Modern 35,000 years BP to present
• Anatomically modern
• Sometimes called Homo sapiens sapiens

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Cro-Magnon Man

• Cro-Magnon humans
• 35,000 years B.P. in western Europe to 17,000
  years B.P.
• 1,600 cc cranial capacity
• Name comes from a hotel in France
• Not a different species, just old Homo sapiens
  from Europe

Artists reconstruction of a Cro-Magnon man
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Archaic H. sapiens Culture

• Art
• Traces of art found in beads, carvings, and
  paintings
• Cave paintings in Spain and southern France
  showed a marked degree of skill
• Female figurines
• 27,000 to 22,000 years B.P.
• Called venuses, these figurines depicted women
  with large breasts and broad hips
• Perhaps it was an example of an ideal type, or
  perhaps an expression of a desire for fertility

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Archaic H. sapiens Culture
Cave paintings from 20,000 years ago at
Vallon-Pont-dArc in southern France (left) and
from Lascaux, in southwest France

• Cave paintings
• Mostly animals on bare walls
• Subjects were animals favored for their meat and
  skins
• Human figures were rarely drawn due to taboos and
  fears that it would somehow harm others

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Upper Palaeolithic Hotbed of Culture

• 40 10k yBP
• Shelters
• 15,000 yBP Ukraine
• Some made with mammoth bones
• Wood, leather working carpentry
• Tools
• From cores to blades
• Specialization
• Composite tools
• Bow and arrow
• Domestication of dogs
• Gathering rather than hunting became the mainstay
  of human economies.

Top Straw Hut Left Mammoth bone hut Bottom
Tool progression
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Modern Homo Sapiens

• Regional-Continuity Model (Milford Wolpoff,
  UMich)
• Humans evolved more or less simultaneously across
  the entire Old World from several ancestral
  populations.
• Rapid-Replacement Model (Chris Stringer, NHM
  London)
• Humans evolved only once--in Africa from H.
  heidelbergensis ancestors--and then migrated
  throughout the Old World,

• replacing their archaic predecessors. Also
  called the Out of Africa and Killer Ape
  hypothesis.

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Social Organization

• Hunter-gatherer analogy
• Small group, low population density, nomadism,
  kinship groups
• Migration
• North America was the last colonized by hominids.
• Beringia (land bridge) between Russia and Alaska
• Asian origin of Native Americans
• 30,000 to 12,000 years B.P. was first migration

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Hominid Evolution

• Major Homo advances
• Brain size
• Better bipedalism
• Hunting
• Fire (H. erectus)
• Tools
• Oldowon (H. habilis)
• Acheulean (H. erectus)
• Mousterian (H. heidelbergensis)
• Solutrean (H. sapiens)
• Built shelters (H. heidelbergensis)
• Clothing (H. neandertalensis)
• Language (Neandertals?)

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Thomas Sutikna (the Indonesian Centre for
Archaeology) and Homo floresiensis
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