Biology
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32-3 Primates and
Human Origins
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32-3 Primates and Human Origins
What Is a Primate?
What characteristics do all primates
share?
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32-3 Primates and Human Origins
What Is a Primate?
What Is a Primate?
In general, primates have binocular
vision, a well-developed cerebrum,
relatively long fingers and toes, and
arms that can rotate around their
shoulder joints.
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32-3 Primates and Human Origins
What Is a Primate?
Fingers, Toes, and Shoulders
Flexible digits enable primates to run along tree
limbs and swing from branch to branch with ease.
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32-3 Primates and Human Origins
What Is a Primate?
Primates’ arms are well adapted to climbing because
they can rotate in broad circles around a strong
shoulder joint.
In most primates, the thumb and big toe can move
against the other digits. This characteristic allows
primates to hold objects in their hands or feet.
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What Is a Primate?
Well-Developed Cerebrum
The large cerebrum of primates enables them to
display more complex behaviors than many other
mammals.
Many species have social behaviors that include
adoption of orphans and even warfare between
rival primate troops.
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32-3 Primates and Human Origins
What Is a Primate?
Binocular Vision
Many primates have a flat face, so both eyes face
forward with overlapping fields of view. This facial
structure allows for binocular vision.
Binocular vision is the ability to merge visual
images from both eyes, providing depth perception
and a three-dimensional view of the world.
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32-3 Primates and Human Origins
Evolution of Primates
What are the major evolutionary groups of
primates?
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32-3 Primates and Human Origins
Evolution of Primates
Evolution of Primates
The two main groups of primates are
prosimians and anthropoids.
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32-3 Primates and Human Origins
Evolution of Primates
Hominoids
New
Lorises and
WorldOld World
bush babies
monkeys
LemursTarsiers
Gibbons
Gorillas
monkeys
Orangutans
Chimpanzees
Humans
Prosimians
Primate ancestor
Anthropoids
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32-3 Primates and Human Origins
Evolution of Primates
Prosimians
Most prosimians alive today are small, nocturnal
primates with large eyes that are adapted to
seeing in the dark.
Living prosimians include bush babies, lemurs,
lorises, and tarsiers.
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32-3 Primates and Human Origins
Evolution of Primates
Lorises and
bush babies Lemurs Tarsiers
Prosimians
Primate ancestor
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32-3 Primates and Human Origins
Evolution of Primates
Anthropoids
Humans, apes, and most monkeys belong to a
group called anthropoids, which means
humanlike primates.
This group split early in its evolutionary history into
two major branches.
These branches separated as drifting continents
moved apart.
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32-3 Primates and Human Origins
New World Old World
monkeys monkeys Gibbons
Evolution of Primates
Orangutans
Gorillas ChimpanzeesHumans
Anthropoids
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32-3 Primates and Human Origins
Evolution of Primates
One branch of anthropoids is the New World
monkeys. New World monkeys:
•
live almost entirely in trees.
•
have long, flexible arms to swing from
branches.
•
have a prehensile tail, which is a tail that can
coil around a branch to serve as a “fifth hand.”
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32-3 Primates and Human Origins
Evolution of Primates
The other group of anthropoids includes Old World
monkeys and great apes.
•
Old World monkeys live in trees but lack
prehensile tails.
•
Great apes, also called hominoids, include
gibbons, orangutans, gorillas, chimpanzees,
and humans.
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32-3 Primates and Human Origins
Hominid Evolution
Hominid Evolution
Between 6 and 7 million years ago, the hominoid
line gave rise to hominids. The hominid family
includes modern humans.
As hominids evolved, they began to walk upright
and developed thumbs adapted for grasping.
They also developed large brains.
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32-3 Primates and Human Origins
Modern human
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Hominid Evolution
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32-3 Primates and Human Origins
Hominid Evolution
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32-3 Primates and Human Origins
Hominid Evolution
The skull, neck, spinal column, hipbones, and leg
bones of early hominid species changed shape in
ways that enabled later hominid species to walk
upright.
Evolution of this bipedal, or two-foot, locomotion
freed both hands to use tools.
Hominids evolved an opposable thumb that enabled
grasping objects and using tools.
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32-3 Primates and Human Origins
Hominid Evolution
Hominids displayed a remarkable increase in brain
size, especially in an expanded cerebrum—the
“thinking” area of the brain.
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32-3 Primates and Human Origins
Hominid Evolution
Early Hominids
At present, the hominid fossil record includes these
genera:
•
•
•
•
•
Ardipithecus
Australopithecus
Paranthropus
Kenyanthropus
Homo
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32-3 Primates and Human Origins
Hominid Evolution
There are as many as 20 separate hominid species.
This diverse group of hominid fossils covers roughly
6 million years.
All are relatives of modern humans, but not all are
human ancestors.
Questions remain about how fossil hominids are
related to one another and to humans.
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32-3 Primates and Human Origins
Hominid Evolution
Australopithecus
An early hominid species, Australopithecus, lived
from about 4 million to 1 million years ago.
The structure of Australopithecus teeth suggests a
diet rich in fruit.
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32-3 Primates and Human Origins
Hominid Evolution
The best known species is Australopithecus
afarensis—based on a female skeleton
named Lucy, who was 1 meter tall.
Members of the Australopithecus species
were bipedal and spent some time in trees.
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32-3 Primates and Human Origins
Hominid Evolution
Paranthropus
The Paranthropus species had huge, grinding back
teeth.
Their diets probably included coarse and fibrous
plant foods.
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32-3 Primates and Human Origins
Hominid Evolution
Recent Hominid Discoveries
In 2001, a team had discovered a skull in Kenya.
• Its ear resembled a chimpanzee’s.
• Its brain was small.
• Its facial features resembled those of Homo
fossils.
• It was put in a new genus, Kenyanthropus,
which lived at the same time as A. afarensis.
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32-3 Primates and Human Origins
Kenyanthropus platyops
Hominid Evolution
Homo erectus
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32-3 Primates and Human Origins
Hominid Evolution
In 2002, paleontologists working in the desert in
north-central Africa discovered another skull.
•
Called Sahelanthropus, it is nearly 7 million
years old.
•
If it is a hominid, it would be a million years
older than any hominid previously known.
•
It had a brain like a modern chimp and a flat
face like a human.
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32-3 Primates and Human Origins
Hominid Evolution
Sahelanthropus tchadensis
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32-3 Primates and Human Origins
Hominid Evolution
What is the current scientific thinking
about hominid evolution?
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32-3 Primates and Human Origins
Hominid Evolution
Rethinking Early Hominid Evolution
Researchers once thought that human evolution
took place in steps, in which hominid species
became gradually more humanlike.
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32-3 Primates and Human Origins
Hominid Evolution
Hominid evolution did not proceed by the
simple, straight-line transformation of one
species into another.
Rather, a series of complex adaptive
radiations produced a large number of
species whose relationships are difficult
to determine.
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32-3 Primates and Human Origins
Millions of years ago
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Hominid Evolution
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32-3 Primates and Human Origins
Hominid Evolution
The hominid fossil record dates back 7 million years,
close to the time that DNA studies suggest for the
split between hominids and the ancestors of modern
chimpanzees.
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32-3 Primates and Human Origins
The Road to Modern
Humans
The Road to Modern Humans
Paleontologists still do not completely understand
the history and relationships of species within our
own genus.
Other species in the genus Homo existed before
Homo sapiens.
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32-3 Primates and Human Origins
The Road to Modern
Humans
The Genus Homo
The first fossils in the genus Homo are about 2.5
million years old.
These fossils were found with tools, so
researchers called the species Homo habilis,
which means “handy man.”
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The Road to Modern
Humans
2 million years ago, a species called Homo ergaster
appeared. It had a bigger brain and downward-facing
nostrils that resembled those of modern humans.
At some point, either H. ergaster or a related species
named Homo erectus began migrating out of Africa
through the Middle East.
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32-3 Primates and Human Origins
The Road to Modern
Humans
Out of Africa—But Who and When?
Evidence suggests that hominids left Africa in
several waves, as shown in the following diagram.
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32-3 Primates and Human Origins
The Road to Modern
Humans
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32-3 Primates and Human Origins
The Road to Modern
Humans
It is not certain where and when Homo sapiens
arose.
One hypothesis, the multi-regional model, suggests
that modern humans evolved independently in
several parts of the world from widely separated
populations of H. erectus.
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32-3 Primates and Human Origins
The Road to Modern
Humans
Another hypothesis, the out-of-Africa model,
proposes that modern humans evolved in Africa
between 200,000–150,000 years ago, migrated out
to colonize the world, and replaced the descendants
of earlier hominid species.
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32-3 Primates and Human Origins
Modern Homo sapiens
Modern Homo sapiens
The story of modern humans over the past
500,000 years involves two main groups.
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32-3 Primates and Human Origins
Modern Homo sapiens
The earliest of these species is called Homo
neanderthalensis.
Neanderthals lived in Europe and Asia 200,000–
30,000 years ago.
They made stone tools and lived in organized social
groups.
The other group is Homo sapiens—people whose
skeletons look like those of modern humans.
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32-3 Primates and Human Origins
The Road to Modern Humans
50,000–40,000 years ago some populations of H.
sapiens seem to have changed their way of life:
•
They made more sophisticated stone blades
and elaborately worked tools from bones and
antlers.
•
They produced cave paintings.
•
They buried their dead with elaborate rituals.
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32-3 Primates and Human Origins
The Road to Modern Humans
About 40,000 years ago, a group known as CroMagnons appeared in Europe.
By 30,000 years ago, Neanderthals had disappeared
from Europe and the Middle East.
Since that time, our species has been Earth’s only
hominid.
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32-3
Click to Launch:
Continue to:
- or -
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The ability to merge visual images from both
eyes is called
a. monocular vision.
b. binocular vision.
c. overlapping vision.
d. color vision.
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Which of the following is true about hominid evolution?
a. The development of a large brain happened before
bipedal locomotion.
b. There is a straight line of descent from the earliest
hominid species to Homo sapiens.
c. The genus Homo appeared before the genus
Australopithecus.
d. Hominid evolution took place as a series of adaptive
radiations that produced a large number of species.
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The evolution of bipedal locomotion was
important because it
a. increased brain size.
b. made it easier to see.
c. freed both hands to use tools.
d. allowed easier escape from predators.
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The multi-regional model hypothesizes that
a. Homo sapiens evolved independently in
several parts of the world.
b. Modern humans evolved in Africa, then
migrated to various parts of the world.
c. Neanderthals produced cave drawings.
d. Homo habilis descended from Homo erectus.
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The oldest known Homo sapiens skeletons are
about
a. 6,000 years old.
b. 100,000 years old.
c. 3 million years old.
d. 30 million years old.
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