Download - Hominid Evolution. Early Primates 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
1. Australopithecus afarensis Cranium
2. Australopithecus africanus Cranium
3. Homo habilis Cranium
4. Homo erectus Cranium
5. Neandertal Cranium
Some major characteristics of hominid evolution
•Jaw shape
•Bipedal posture
•Reduced size difference between the sexes
•Brain size
•Family structure
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In the course of primate evolution,there has been a trend toward longer periods of juvenile dependency
AdultJuvenileInfancyGestation
Two main groups of hominids
Homo (2.5 mya)Australopithecines (4 mya) (Australopithecus, Paranthropus)
Gracile
small boned ape-like forms(A. africanus, A. afarensis)
Robust
ape-like forms(A. boisei, A. robustus)
A. boiseiA. africanus
Australopithecines are divided into two groups
A. robustus
Skull specialized for heavy chewing
large cheek teeth
large jaw
robust zygomatic arches
prominent saggital crest
Skull morphology suggests a more generalized approach to food
A. africanus
smaller molars
absence of bony crests for heavy chewing
•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
Australopithecus africanus 3 – 2.3 mya
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
3.5 my old Hominin footprints in the volcanic ash in Laetoli, Tanzania
Lucy skeleton
paleoanthropologists have found hominid species that predate A. afarensis
1994A. anamensis was
discoveredby Maeve Leakey in KenyaLived just over 4.2 – 3.9
mya
Found:Upper/lower jawsCranial fragmentsUpper and lower parts of leg bone
1995, Ardipithecus (possibly predates A. afarensis)
2001, Kenyanthropus platyops (3.5 – 3.2 mya)
Australopithecus garhi
Discovered 1996
Berhane Asfaw & Tim White
Ethiopia Afar Basin
Garhi means “surprise”
Prehominid Evolution
Reconstruction of Australopithecine
• 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
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)
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
Ardipithecus ramidus
Discovered by Tim White 1995
Oldest known hominid (about 4.4 million years ago)
Fragments of skull remains and skeleton found in theAfar 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?
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
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
Artist’s representation of a Homo habilis band as it might have existed two million years ago.
• 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
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 industryPhotograph 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
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
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-aux-Saints.
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 caveBottom: Mousterian tools
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– 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
Cave paintings from 20,000 years ago at Vallon-Pont-d’Arc in southern France (left) and from Lascaux, in southwest France
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
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– 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:– 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?)