Chapter 32-3
Mammals
32-3 Primates and Humans
Copyright Pearson Prentice Hall
32-3 Primates and Human
Origins
Copyright Pearson Prentice Hall
Mammals: Primates
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Evolution of Primates
Evolution
of Primates
The
two main groups of primates are
prosimians and anthropoids.
Copyright Pearson Prentice Hall
Evolution of Primates
Hominoids
Lorises and
Bush Babies
Lemurs
New
Old World
World
Monkeys Orangutans Chimpanzees
Monkeys
Gibbons
Gorillas
Humans
Tarsiers
Prosimians
Primate ancestor
Copyright Pearson Prentice Hall
Anthropoids
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.
Copyright Pearson Prentice Hall
Order Primates
Prosimian: A Lemur
Monkeys are Anthropoids
Order Primates
Evolution of Primates
Lorises and
Bush Babies Lemurs Tarsiers
Prosimians
Primate Ancestor
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Evolution of Primates
New World Old World
Orangutans
Gorillas Chimpanzees Humans
monkeys
monkeys Gibbons
Anthropoids
Copyright Pearson Prentice Hall
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.”
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Hominid Evolution
Modern human
Copyright Pearson Prentice Hall
Hominid Evolution
Modern human
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Hominid Evolution
Hominids
displayed a remarkable increase in
brain size, especially in an expanded
cerebrum—the “thinking” area of the brain.
Copyright Pearson Prentice Hall
Hominid Evolution
Early
Hominids
At present, the hominid fossil record includes
these genera:
 Ardipithecus
 Australopithecus
 Paranthropus
 Kenyanthropus
 Homo
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Hominid Evolution
Paranthropus
The
Paranthropus species had huge, grinding
back teeth.
Their diets probably included coarse and fibrous
plant foods.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Hominid Evolution
Kenyanthropus platyops
Homo erectus
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Hominid Evolution
Sahelanthropus tchadensis
Copyright Pearson Prentice Hall
Hominid Evolution
Rethinking Early Hominid Evolution
Researchers once thought that human
evolution took place in steps, in which hominid
species became gradually more humanlike.

Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Hominid Evolution
Millions of years ago
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Known or Suspect Hominids
Simplified Tree
Australopithicus afarensis
Homo habilis
Homo erectus
 H. erectus lived from approximately 1.8
to 0.5 million years ago and perhaps
even longer
 H. erectus was the most successful of the
the genus Homo lineages in terms of
time on Earth
 H. erectus spread her kind throughout
the old world
H. erectus
Homo erectus
Pan
Homo
erectus
H. sapiens
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.
Copyright Pearson Prentice Hall
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.”
Copyright Pearson Prentice Hall
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.

Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
The Road to Modern Humans
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Modern Homo sapiens
Modern
Homo sapiens
The
story of modern humans over the past 500,000 years
involves two main groups.
Copyright Pearson Prentice Hall
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.
Copyright Pearson Prentice Hall
Modern Homo sapiens
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.
Copyright Pearson Prentice Hall
Modern Homo sapiens
About
40,000 years ago, a group known as
Cro-Magnons 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.
Copyright Pearson Prentice Hall
32-3 Quiz
Copyright Pearson Prentice Hall
32-3





The ability to merge visual images from both
eyes is called
monocular vision.
binocular vision.
overlapping vision.
color vision.
Copyright Pearson Prentice Hall
32-3

a.
b.
c.
d.
Which of the following is true about hominid
evolution?
The development of a large brain happened
before bipedal locomotion.
There is a straight line of descent from the
earliest hominid species to Homo sapiens.
The genus Homo appeared before the genus
Australopithecus.
Hominid evolution took place as a series of
adaptive radiations that produced a large
number of species.
Copyright Pearson Prentice Hall
32-3





The evolution of bipedal locomotion was
important because it
increased brain size.
made it easier to see.
freed both hands to use tools.
allowed easier escape from predators.
Copyright Pearson Prentice Hall
32-3





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.
Copyright Pearson Prentice Hall
32-3





The oldest known Homo sapiens skeletons are
about
6,000 years old.
100,000 years old.
3 million years old.
30 million years old.
Copyright Pearson Prentice Hall
END OF SECTION