Homework
Guided Reading – Hominids Through
Time (#12-21)
Learning Target
I can explain how hominids evolved and
what caused them to evolve.
What characteristics do they have in common?
What characteristics are different?
Characteristics of All Primates

Binocular vision:
◦ Eyes both on the front of the head.
◦ Each eye sees a slightly different view of the
same scene and the brain merges them to allow
depth perception.
Flat finger nails
 Five flexible fingers (four fingers and an opposable
thumb)

◦ Most primates (besides humans) also have opposable big toes
◦ Gorilla Foot
How are humans different from other primates?

Bipedal (2 legs)  skeleton is adapted for walking
upright
◦
◦
◦
◦

Human pelvis is vertical (holds skeleton upright)
Gorilla pelvis tips ribcage, head, and neck forward
Human spine is “S” shaped
Gorilla spine is “C” shaped
What else?
Make a prediction…
 What
are several advantages
of being bipedal?
Which are bipedal advantages?
A. Easier birth
B. Less heat absorbed
C. Walk further
D. Can climb trees better
E. Faster
F. No back problems
G. Use of hands for carrying
H. Greater field of vision
Which are bipedal advantages?
Bipedal Advantages
Bipedal Disadvantages
1. Walk further
1. More difficult births
2. Use hands for carrying
2. Slower
3. Greater field of vision
3. Back problems with age
4. Less heat absorbed
4. Can not climb trees as well
What came first bipedalism or large
brains?
Originally thought that large brain size came first,
followed by things like bipedalism, changes in diet,
and changes in behavior
 The fossil evidence shows that bipedalism came
first. The oldest fossils of hominids had cranium
sizes similar to the size of apes but showed evidence
of walking upright.

◦ Bipedalism ~4mya
◦ Big brains and tool use ~2.5mya
What is a hominid?

Hominid
◦ Group of bipedal primates that includes humans and their
extinct ancestors
◦ Missing links between humans and apes

Homo sapiens
◦ Modern human species dating back to 100,000/200,000
years ago
We did NOT come from Chimps
We share a common ancestor
 We share about 99% DNA with chimps, which
means they are our closest PRIMATE relative.
 Common ancestor is predicted to have existed
around 6-7 mya

From “Lucy” to us!
Most hominins in the last 4
million years fit into one of
two genera (plural of genus):
Australopithecus or Homo.
Lucy was one of the first
Australopithecines and her
descendants eventually gave
rise to other species of
Australopithecus.
Homo
sapiens
Lucy
At some point, around 2 million years ago, one of Lucy’s descendant
species gave rise to a new genus, Homo, with significantly larger and
much more advanced brains. This is the branch that led to
Neanderthals and modern humans!
Two Main Hominid Groups
Genus: Australopithecus
example:
A. afarensis
(“Lucy”)
• Earlier (4 – 1.5 MYA)
• More ape-like
• Brain size: similar to
the size of chimpanzees
• First bipedal primates
• Found in Africa
Genus: Homo
example:
H. erectus
• More recent
(2 MYA – present)
• More human-like
• Much larger brain
• Completely bipedal
• Found in Africa, Asia,
and Europe
Two Main Hominid Groups
Relative size of humans
compared to the
Australopithecine genus.
Australopithecus
afarensis
3.9-3.2 MYA
The Oldest of the bunch! This is “LUCY”
Homo
neanderthalensis
200,000 - 28,000
years ago
• Predate Homo sapiens
• Coexisted alongside humans
• Some paleo-anthropologists consider
Neanderthals to be a sub-species of Homo
sapiens
• Think they may even have been able to
interbreed
Homo
sapiens
100,000-200,000
to present
Homo sapiens evolved
about 100,000-200,000
years ago
1 blade of grass
To put that into
perspective:
Noon = 1st hominids
11 pm = Neanderthals
11:30 pm = Homo sapiens
Where did hominids first evolve?
East Africa
How did hominids evolve?
•
•
5-10 mya—Eastern Africa becomes cooler and drier
Unbroken tropical forests become a patchwork of
woodland and savannah (grassland)
Western and Central Africa remain more densely
wooded
◦ Primates in Western and Central Africa remain in
the trees
◦ **Some primates in Eastern Africa become
Bipedalism made it easier to…
•
Spot predators
•
Travel long distances
•
Pick fruit off trees
•
Freed up 2 limbs
•
*Carry food from one location to another
•
**Use tools!
If bipedalism came first, what caused
brains to increase in size?
•
•
Use of 2 free limbs
Constant climate change
◦ Had to be able to adapt quickly as a species or die
•
Change in diet
◦ Early members of the Homo genus began to eat more meat
 Many more calories for the body than plant material
◦ Scientists propose Homo erectus was probably the first hominid to “cook” food using fire
 Helps unlock additional nutrients to be digested easier
**The more calories and nutrients consumed, the more the brain can grow**
When and where did Homo sapiens evolve?

Roughly 100,000-200,000 years ago, most likely in Africa
When and where did Homo sapiens
evolve?
So far fossil
evidence
also points to
East Africa
Genetic
evidence also
points to East
Africa as our
origin.
The Great Rift Valley
Remember: There have been hundreds
of fossilized hominin specimens found
since the mid 1800s.
The earliest hominins
(Australopithecines) are only
found in Africa, while
members of our own genus
(Homo) migrated into Europe
and Asia.
Place events in order under their correct
change: Geologic; Climate; Habitat &
Species
1.
Savanna grasslands form in East Africa
2.
Central Africa is all tropical (apes are diverse)
3.
East Africa became cooler & drier due to mountain range
and change in ocean currents
4.
West Africa remained a tropical rainforest
5.
Bipedal primates evolve in East Africa
6.
Great Rift Valley forms isolating East Africa &
connection of North & South America