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Chapter 26.3:
Primates and Human Origins
Mrs. Bertolotti
Essential Question
How have humans descended
from earlier forms during the
process of evolution?
What characteristics do all
primates share?
What is a primate?

Primates have:

A) Binocular visionvision- the ability to merge visual
images from both eyes

Thus results in depth perception and a 33-D view of the
world
B) A wellwell-developed cerebrumcerebrum- results in more
complex behaviors
 C) Relatively long fingers and toestoes- typically 5 and are
flexible



What characteristics do all
primates share?
Opposable thumb
D) Arms that can rotate around their shoulder joints
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Evolution of Primates


What are the major evolutionary
groups of primates?

Humans & other primates evolved from a common ancestor
that lived more than 65 million years ago
Early in the history of primates, primates split into two
groups.
 Primates in one of these groups look very little like
typical monkeys.
 This group consists of lemurs and lorises
 The other group includes tarsiers and the anthropoids,
the group that includes monkeys, great apes and humans
Therefore, primates evolved from 2 of the earliest branches:
 1. prosimians
 2. anthropoids
Prosimians



Are alive today
Small, nocturnal primates with large eyes that are
adapted to seeing in the dark
Example: lemurs of Madagascar
Anthropoids


Humans, apes, and most monkeys belong to this category
 Smaller eyes-eyes--day
day active primates
 Color vision
 Larger brains
Split into 2 categories early in evolutionary history and became separated
during continental drift
 1. New World monkeys
 Found in North and South America
 Examples: Squirrel and spider monkeys
 Live almost entirely in trees (arboreal)
 Possess a prehensile tailtail- a tail that can coil tightly enough around a
branch to serve as a ―fifth‖ hand
 2. Old World monkeys
 found in Africa and Asia
 Example: Macaques
 Spend time in trees but lack a prehensile tail.
 Great apes called hominoids
hominoids-- ex. Chimpanzees and humans
 Chimps share approximately 99% of human DNA
A New World Monkey
using his prehensile tail
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Anthropoids

Anthropoids—
Anthropoids
—3 categories

Monkeys
Have tails
Old World—
World—Asia and Africa
 New World—
World—Central and S. America



Apes
NO TAILS
Larger brains than monkeys
 Chimps, gibbons, orangutans,
bonobo,, etc.
bonobo



Humans


Our closest genetic primate relative is?
THE CHIMPANZEE
What are the major evolutionary
groups of primates?
What adaptations enabled later
hominine species to walk
upright?
Hominid evolution
Hominid evolution
Between 66-7 million years ago, the lineage that led to
humans split from the lineage that led to chimpanzees.

Adaptive radiation may be responsible for the evolution of early
hominids

The hominoids in the lineage that led to humans
are called hominines
hominines..
 Hominines include humans and other species
closely related to us than chimpanzees.
 Example:
Neanderthals.
 Hominines
evolved the ability to walk
upright, use grasping thumbs, and large
brains.

The skull, neck, spinal column, hip bones,
and leg bones of early hominine species
changed shape in ways that enabled later
species to walk upright.
 Being bipedal (ability to walk on two feet)
was important as it freed up both hands to
use tools.
 The opposable thumb allowed the tips of
the fingers to touch the thumb, enabling
the grasping of objects and the use of tools.
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Hominid vs. chimpanzee
Human vs. gorilla
Features
Skull
Spinal cord
Arms and
hands
Pelvis
Thigh bones
Human
Atop S-shaped spine
Exits at bottom of
skull
Arms shorter than legs;
hands don’t touch
ground when walking
Bowl-shaped
Angled inward, directly
below body
Gorilla
Atop C-shaped spine
Exits near back of the
skull
Arms longer than legs;
hands touch ground
when walking
Long and narrow
Angled away from
pelvis

Chimps most closely related primate to
humans—
humans
—99% similarity in the sequence of our
genes!
Human’s jaw more arc shaped with smaller
canines; chimps’ U with larger canines and larger
gaps.
 Hominid spine S–
S– chimps’ is C shaped
 Hominid pelvis is bowlbowl-shaped, chimps’ long
 Hominid thigh bones taper in—
in—chimps’ out
 The hominine hand evolved an opposable
thumb that could touch the tips of the fingers,
enabling the grasping of objects and the use of
tools.

Hominine Evolution
What adaptations enabled later
hominine species to walk
upright?
What is the current scientific
thinking about the evolution of
humans?
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Early Hominids

Genus Australopithecus
LUCY
3.5 million years old
Lucy Australopithecus afarensis
Lucy
 Fossil found in Africa
 Hominids
Hominids—
—shape of pelvis and femurs showed they
were bipedal.
 Short
Short—
—3’6’’
 Brain size of chimps
 Jaws more rounded than apes
 Teeth like humans

40% complete
Female
SKULLS
Lucy had a small skull like an ape, but
she wasn’
wasn’t one.
 LUCY
APE

•Showed us:
•walked upright
first
•brain size grew
AFTER.
SKULLS
A. afarensis (Lucy)
Homo sapien
LUCY
 She
walked upright
 She was a bipedal hominid
 Bowl
Bowl--shaped
pelvis
 Thigh bones taper in
 Locking knee joint
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LUCY VS. APE
Early Hominids
•
Genus Australopithecus
A. afarensis
•
Genus Homo
Homo habilis
H. erectus
H. sapiens
Time
NOT A COMPLETE LIST! THERE ARE OTHERS!
Homo habilis
Homo sapiens
APES
Homo erectus
Homo habilis
transitional species



Australopithecus afarensis


Means: Handy man
Small structure like Lucy
Skull 2X’s the size of Lucy
2- 1.8 mya in Africa
Tools made of bone and stone.
common ancestor to
ape and H. sapiens
Where Did H. sapiens evolve?
Homo erectus

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Java man / Peking man
Africa / Asia / Europe
Larger than H. habilis
Larger brain
Excellent tools, used fire
1.5 mya – ―immediate‖ ancestor
Two hypotheses:

Out of Africa:

states H. sapiens evolved IN Africa and spread to rest of
world

Multiregional

Out of Africa hypothesis supported by most
evidence.

H. erectus left Africa and THEN evolved into H. sapiens
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Neanderthals
Out of Africa - But When and Who?



Researchers agree that our genus originated in Africa and
migrated from there to populate the world.
Some current hypotheses about when hominines first left
Africa and which species made the trip are shown in the
figure..
figure
More recent DNA data suggest that a small subset of
those African ancestors left northeastern Africa between
65,000 and 50,000 years ago to colonize the world,
supporting the outout-of
of--Africa hypothesis.


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
Newsflash!



A comparison of DNA sequences of humans and Neanderthals, the
species of hominid that existed from roughly 400,000 to 30,000 years
ago, revealed some intriguing findings, indicating, for instance, that at
some point after early modern humans migrated out of Africa, they
mingled and mated with Neanderthals, possibly in the Middle East or
North Africa as much as 80,000 years ago.
ago. If that is the case, it occurred
significantly earlier than scientists who support the interbreeding
hypothesis would have expected.
Comparisons with DNA from modern humans show that some
Neanderthal DNA has survived to the present. Moreover, by analyzing
ancient DNA alongside modern samples, the team was able to identify a
handful of genetic changes that evolved in modern humans sometime
after their ancestors and Neanderthals diverged, 440,000 to 270,000 years
ago.
The absence of Neanderthal DNA in the genomes of the two presentpresentday Africans indicates that interbreeding occurred after some root
population of early modern humans left Africa but before the species
evolved into distinct groups in Europe and Asia.
Read more:
http://www.time.com/time/health/article/0,8599,1987568,00.html#ixzz0p2EmJ8Pc
Homo neanderthalensis
discovered in Neander Valley
Went extinct
Massive skulls, protruding brows
Great controversycontroversy- did they die off (genes no
longer present in gene pool) or did they
evolve with us (interbred so genes still in our
gene pool)? Data indicates that interbreeding
occurred in certain populations.
Modern H. sapiens probably evolved in Africa
and replaced Neanderthals.
Neanderthals are closely related to us but we
are not descended from themthem- instead we
share a common ancestor.
NEWSFLASH!!!!!

2009 Recent analysis of
Ardipithecus ramidus
ramidus…
… aka ―Ardi
―Ardi‖‖
found in 1994.



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Lived 4.4 million years ago in what is
now Ethiopia
The last common ancestor shared by
humans and chimpanzees is thought to
have lived six or more million years ago.
A hominid with opposable big toes like
chimps and apes
1.2 million years OLDER than Lucy, and
our oldest known common ancestor
with other primates (4.4 mya
mya)!
)!
47 inches tall
Show that chimps have actually evolved
MORE than humans since our common
ancestor
APES
Mated????
Homo neanderthalensis Homo sapiens
“ARDI”
Ardipithecus
ramidus
transitional species
Homo erectus
Homo habilis
Australopithecus afarensis
common ancestor to
ape and H. sapiens
ARDI?????
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“Race” and evolution

What is the current scientific
thinking about the evolution of
humans?


The considerable range of observed phenotypic variation in
human populations may reflect, in part, distinctive processes of
natural selection and adaptation to variable environmental
conditions.
Race is characterized by the color of an individual’s skin color
and their ancestry. The former, most widely recognized as an
indication of one’s race, is accompanied by the presumption that
the genetic and biological causes responsible for it, originate
from people with a great degree of genetic variations within the
human species. The development of varying skin pigmentation is
not an influential enough of a difference to divide the human
species into races. Skin color is merely a reaction to an
environment. Race is a concept of society that insists there is a
genetic significance behind human variations in skin color that
transcends out ward appearance.
However, race has no scientific merit outside of sociological
classification. There are no significant genetic variations
within the human species to justify the division of “ races.”
Essential Question
How have humans descended
from earlier forms during the
process of evolution?
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