Transcript Slide 1

Hominid Evolution
Early Primates
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•
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Prosimians (65mya)
Monkeys (35mya)
Apes (23mya)
Hominids (5mya)
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
Primate Family Tree
Crown lemur
Orangutan
1. Australopithecus
afarensis Cranium
2. Australopithecus
africanus Cranium
3. Homo habilis Cranium
4. Homo erectus Cranium
5. Neandertal Cranium
Hominid Evolution
Gorilla
Pan
Homo
5 – 7 mya
What features distinguish humans from the other apes?
Gorilla
Pan
Homo
Some major characteristics of
hominid evolution
•Jaw shape
•Bipedal posture
•Reduced size difference between the sexes
•Brain size
•Family structure
1400
Range
1200
In the course of hominid
evolution, there is an
increase in brain volume
Brain volume (cm3)
1000
800
600
400
200
0
In the course of primate evolution,
there has been a trend toward longer
periods of juvenile dependency
Adult
Juvenile
Infancy
Gestation
Two main groups of hominids
Australopithecines (4 mya)
(Australopithecus, Paranthropus)
Homo (2.5 mya)
Australopithecus
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)
Skull specialized for heavy chewing
large cheek teeth
large jaw
robust zygomatic arches
prominent saggital crest
A. robustus
Skull morphology suggests a more
generalized approach to food
smaller molars
absence of bony crests for heavy chewing
A. africanus
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
human’s brain
Taung Child
Were human ancestors hunted by birds?
Research provides a break in the case of a famous
hominid’s death
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.
Upright posture predates an enlarged brain in human evolution
Lucy skeleton
3.5 my old Hominin footprints in the
volcanic ash in Laetoli, Tanzania
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)
Australopithecus
anamensis
Australopithecus garhi
Discovered 1996
Berhane Asfaw & Tim White
Ethiopia Afar Basin
Garhi means “surprise”
Prehominid Evolution
• Ardipithecus ramidus
4.4 - ?
• 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
mya
Reconstruction of Australopithecine
Why Bipedalism?
Evolution of Bipedalism
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Anatomical changes
– Neck (1), chest (2), lower back (3), hips and pelvis
(4), thighs (5), knees (6), feet (7)
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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)
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
Femur not angled in quadrupeds
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
Which of the australopithecines were
evolutionary dead ends and which were
close to or on the lineage that eventually
sprouted the Homo branch?
evolutionary
dead end?
Australopithecus aethiopicus
2.5 mya
-Found in 1985 by Richard Leaky &
Alan Walker
-Lake Turkana in Northern Tanzania
-Commonly called the black skull
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
Australopithecus robustus
Discovered 1938
- Robert Broom
- Often referred to as Paranthropus robustus
- Lived 2-1 mya
And now…
the Hominids
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)
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
Artist’s representation of a Homo
habilis band as it might have existed
two million years ago.
• no speech
Oldowan tools
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.
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
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
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.
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
Homo erectus
Most fossils found in the Lake Turkana
region of northern Kenya
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.
Homo Erectus
1st to control use of fire which lead to:
• Better health
• Better hunting
• Warmth in colder climates
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
When and where did anatomically
modern humans originate?
Figure 34.41 Two hypotheses for the origin of anatomically modern humans
(emerge btwn. 160,000-154,000 ya,)
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.
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
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
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-auxSaints.
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
Neanderthals
vs
Cro Magnons
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
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
Artist’s reconstruction of a Cro-Magnon man
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
Archaic H. sapiens Culture
Cave paintings from 20,000 years ago at
Vallon-Pont-d’Arc 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
Upper Palaeolithic –
Hotbed of Culture
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40 – 10k yBP
Shelters
– 15,000 yBP Ukraine
– Some made with mammoth bones
– Wood, leather working;
carpentry
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Tools
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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
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.
Social Organization
• Hunter-gatherer analogy
– Small group, low population density, nomadism, kinship
groups
• Migration
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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
Hominid Evolution
• Major Homo advances:
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Brain size
Better bipedalism
Hunting
Fire (H. erectus)
Tools
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Oldowon (H. habilis)
Acheulean (H. erectus)
Mousterian (H. heidelbergensis)
Solutrean (H. sapiens)
– Built shelters (H.
heidelbergensis)
– Clothing (H. neandertalensis)
– Language (Neandertals?)
Thomas Sutikna (the Indonesian Centre for Archaeology)
and Homo floresiensis