Transcript Anatomy & Physiology Unit 6: Human Evolution

Anatomy & Physiology Unit 6:
Human Evolution
Classification Hierarchy
Kingdom
Animal
Phylum
Chordate
Class
Mammal
Order
Primates
Family
Hominids
Genus
Homo
Species
Sapiens
Evolution of Primates
•
The evolution of primates is characterized
by trends towards:
– mobile limbs
– grasping hands (with opposable thumbs)
– a flattened face
– binocular vision
– a large, complex brain (for learned behavior)
– a reduced reproductive rate
Mobile Limbs
•
•
Most primates have flat nails as well as
sensitive pads on the undersides of fingers
and toes.
– Many also have both an opposable big
toe and thumb.
Mobile limbs and clawless opposable digits
allow primates to freely grasp and release
tree limbs.
Primate Hands
Binocular Vision
•
Stereoscopic vision and resultant depth
perception allows primates to make
accurate judgments about distance and
position of adjoining tree limbs.
Evolution of Primates
•
Prosimians were the first type of primate to
diverge from the ancestral primate line.
•
Surviving anthropoids are classified into
three superfamilies.
–
–
–
New World monkeys
Old World monkeys
Hominoids
Hominoid Evolution
•
Proconsul is believed ancestral to hominids.
Evolution of Hominids
•
Phylogenetic tree indicates humans are
most closely related to African apes.
–
Last common ancestor appears to have
lived about 5-7 million years ago (mya)
 Genetic changes used as a molecular
clock to measure relatedness of
different groups.
Hominids
•
To be a hominid, a fossil must have an
anatomy suitable for standing erect and
walking on two feet.
–
Bipedalism
 Human anatomy differs from that of an
ape largely because humans are
bipedal while apes are quadrupedal.
Australopithecines
•
It is possible that one of the
australopithecines that evolved and
diversified in Africa 4 mya is a direct
ancestor of humans.
– Southern Africa
 Australopithecus africanus
– Eastern Africa
 Australopithecus afarensis (Lucy)
Lucy
•
A reconstruction of
Lucy’s skeleton
•
Lucy is ~ 3.5-millionyears-old
– Australopithecus
afarensis
–
adaptations in Lucy’s hip, leg
and foot allowed a fully
bipedal means of locomotion
Hominid Footprints
•
Preserved in volcanic
ash in Tanzania
– Discovered in 1978
– Proved hominids
were bipedal
walkers at least 3.5
million years ago
– Most scientists think
the footprints were
made by A.
afarensis, whose
fossils are found
nearby
Landscape with A. afarensis
Re-creation
of a Pliocene
landscape
showing
members of
A. Afarensis
gathering
and eating
various fruits
and seeds
Evolution of Early Homo
•
Homo habilis, dated between 2.0 an 1.9
mya, may be ancestral to modern humans.
–
Skulls suggest portions of the brain
associated with speech were enlarged.
 Ability to speak may have led to hunting
cooperatively and the advent of culture.
Human Evolution
Skull of Homo erectus
•
A reconstruction
of the skull of
Homo erectus
–
–
a widely
distributed
species
whose remains
have been found
in Africa, Europe,
India, China, and
Indonesia
Homo erectus
•
Homo erectus and like fossils are found in
Africa, Asia, and Europe and are dated
between 1.9 and 0.3 mya.
– Larger brain and flatter face than Homo
habilis.
– Much taller than previous hominids.
– Believed to have first appeared in Africa
and then migrated into Asia and Europe.
– First hominid to use fire.
•
Homo erectus Using Tools
Re-creation of a Pleistocene setting in
which Homo erectus use fire & stone tools
Evolution of Modern Humans
•
Most researchers believe Homo sapiens
evolved from Homo erectus.
– Multiregional Continuity Hypothesis
 Similar evolution occurred in many
different places.
– Out-of-Africa Hypothesis
 H. sapiens evolved from H. erectus only
in Africa, and thereafter migrated to
Europe.
Evolution of Modern Humans
Neanderthals
•
Neanderthal (H. neanderthalensis)
skeletons were first discovered in
Germany’s Neander Valley.
– Skeletons date back 200,000 years.
 Massive brow ridges with protruding
nose, jaws, and teeth.
 Heavily muscled.
 Culturally advanced.
 Manufactured variety of tools.
•
Reconstructed
Neanderthal
skull
characterized
by prominent heavy
brow ridges and week chin
•
Burial Ceremony in a Cave
Neanderthals lived in caves and had
ritual burials, such as this depiction
from Shanidar Cave, Iraq
Neanderthals
(190,000 – 27,000 yrs ago)
Flaked stones
that fit in wood
handles.
Buried their dead
with spices and
bedding.
Built sturdy huts.
Made flutes!
A flute formed from a femur & 4 remaining holes.
Cro-Magnons – Homo sapiens
•
•
Oldest fossils to be designated H. sapiens.
Modern humans who entered Asia and
Europe from Africa 100,000 years ago.
–
–
–
Made advanced stone tools.
Accomplished hunters.
 Hunted cooperatively.
First to have complex language?
Painting From a Cave in France
•
Cro-Magnons were very skilled cave painters
•
Painting of a horse from a cave in France
Homo Floresiensis
(hobbits)
- one meter high
- lived in Flores
12,000 yrs ago
- Upright posture
- 380 cc cranial
size (like a chimp)
The shapes & sizes
of hominid heads
can be seen to
evolve with time.
Australopithecus vs. Modern
Australopithecus, 4-3 myrs ago
Chimpanzee
Modern human
Cranial Comparisons
Homo Erectus
Neanderthal
Homo Sapiens
Cultural Evolution
•
With the appearance of Cro-Magnons,
– human evolution has become almost
entirely cultural rather than biological
•
Humans have spread throughout the world
– by devising means to deal with a broad
range of environmental conditions
Homo Sapiens
100,000 yrs ago
Art: Cave Paintings, Venuses
Oldest paintings: Chauvet (32,000 yrs old)
Peche Merle (15,000 yrs old)
Lascaux (17,000 yrs old)