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HUMAN EVOLUTION
Classification Hierarchy
Kingdom AnimalPhylum ChordateClass MammalOrder Primates Family Hominids
Genus Homo
Species Sapiens
Important Vocabulary
Paleoanthropologist Scientist who studies
fossil evidence of human evolution.
Homininds Group that includes
humans and their immediate ancestors.
Background
It is very rare to find a complete skeleton of a fossilized hominid. Scientists need to look at many different things to try
and piece together the puzzle of human evolution.
Background Cont’d When hominid fossils are found, several important
characteristics can help determine origin and lifestyle of the species. Did organism walk upright?
Curvature of spine, position where spine attaches to skull and shape of pelvis
Brain size? Examine skull fragments
Diet? Wear and tear on fossilized teeth
How and where did it live? Fossils found in same area & environment found
Primates 2 Divisions of
Primates 1. Anthropoid
primates 2. Prosimean
primates Characteristics:
Flat Nails (no claws) Prehensile hands and
feet (grasping) Color vision and
depth perception
Anthropoid Primates Include:
marmosets Monkeys Apes Humans
Brain size Large relative
to their body size
Opposable thumbs
Similar dental formula number and
arrangement of teeth
HUMANS Bipedalism – Ability to walk on
2 feet Aligned toes = Bipedalism Enlarged brain =Vertical face Areas for speech in the brain S- shaped spine Bowl-shaped pelvis
Prosimean primates
Include: Lemurs Lorises Tarsiers
Tarsier Skeleton
Hominids
Hominids include humans and extinct humanlike primates
The oldest known hominid fossils are between 6 and 7 million years old
First fossils found in Africa
Australopithecus
Oldest known genus of hominids Lived more than 4 million years ago Knee joints- Allow bipedalism! Australopithecus anamensis Australopithecus afarensis – believed to have
given rise to: A. africanus A. robustus A. boisei
more than 1 million years ago
NOT ancestral to modern humans!
Australopithecus vs. Modern
Australopithecus, 4-3 myrs ago Modern human
Chimpanzee
A. africanus
!
A. boiser
!
Discovery of Lucy!
Fossils of nearly half complete early hominid Australopithecus afarensis
suggests hominids became bipedal before their brains began to dramatically enlarge
Ardipithecus ramidus
Recent discovery Not clear whether it was bipedal 4.4 million years old
Existence of hominid species not ancestral to modern humans implies…
Hominid phylogenetic tree is very branchy in appearance
Representing species died out, leaving no descendants.
Early Members of the genus HomoH. habilis & H. erectus
Ancestors to modern humans Larger brains than australopithecines May have had speech Started to develop tools
Homo habilis Homo erectus
Cranial Comparisons
Neanderthal Homo Erectus Homo Sapiens
Neanderthals
For years, the thinking among anthropologists was that homo sapiens, being superior to Neanderthal man, ran him off the planet. More recently, that view has been discarded and the picture become more complicated. For one thing, Neanderthals may have mixed with the ancestor of modern man, which means that we could be carrying Neanderthal genes.
Reconstructed Neanderthal skull
characterized by prominent heavy
brow ridges and week chin
Cro-Magnons
Cro-Magnons coexisted with Neanderthals in Europe and the Middle East for as many as 50,000 years
Cro-Magnons had domed heads, smooth brows, and prominent chins
30,000-year-old Cro-Magnon artifacts include: Bone flutes Ivory sculptures Evidence of elaborate burial
ceremonies
Cro-Magnon Cave Painting
Homo sapiens
Evolved about 800,000 years ago A) Neanderthals
Were early Homo sapiens They may be ancestral to modern humans OR They may have died out and been replaced by
modern humans
Some hypotheses:
1. some anthropologist think H. sapiens evolved in PARALLEL from populations of H. erectus all over the world. (interbreeding)
2. some anthropologists propose that H. sapiens DESCENDED from H. erectus in Africa and then dispersed across Earth.
Evolution of Modern Humans
Human Evolution
Piltdown Man (1912)Charles Dawson fake 1953
preceding Neanderthals
*
Waves of Hominid Emigration
Two hypotheses have been proposed for the evolution of Homo sapiens “African replacement” hypothesis
Also called Out of Africa, Recent-African-Origin “Multiregional origin” hypothesis
“African Replacement” Hypothesis
Members of the genus Homo made repeated long-distance migrations out of Africa beginning 1.8 million years ago
H. sapiens emerged from Africa about 150,000 years ago and spread across the Near East, Europe, and Asia
The dispersing H. sapiens populations replaced all other hominids
Evolution of Modern Humans
“Multiregional Origin” Hypothesis
H. erectus emerged from Africa 1.8 million years ago and spread across the Near East, Europe, and Asia
Continued migrations and interbreeding occurred among widespread H. erectus populations
Regional populations of H. erectus evolved into H. sapiens
Evolution of Modern Humans