2. Early Hominins

Question 1

What is a hominid?

Answer 1

Humans, apes, and all great apes that are alive or extinct

Question 2

What is a hominis?

Answer 2

Bipedal hominids

Question 3

What are the skeletal traits that indicate bipedalism?

Answer 3

Foramun Magnum
barrel shaped rib cage
vertebral column
lordosis/sacrum
pelvis
limb proportions
valgus knee
foot arch
toe bones

Question 4

Foramum Magnum

Answer 4

Middle/anterior

Question 5

Barrel shaped rib cage?

Answer 5

wide/bowl shaped

Question 6

vertebral column

Answer 6

curved

Question 7

Lordosis/sacrum

Answer 7

less energy to fall forward & center of gravity over hips

Question 8

Pelvis

Answer 8

shorter/wider and helps support organs in place

Question 9

Limb Proportion

Answer 9

LEgs longer than arms

Question 10

Valgus Knee

Answer 10

angled

Question 11

arch in foot

Answer 11

shock absorber/convergent toes

Question 12

toe bones

Answer 12

straight not curved

Question 13

What were some of the theory models?

Answer 13

Provisioning Model, using tools model, Thermoregulatory model, Climbing Mechanical Model,

Question 14

Provisioning model

Answer 14

Males would gather
food and bring it back
to females – hence,
their hands needed to
be free to carry these
items

But, this would mean that
pair-bonding evolved early
Sexual dimorphism
suggests otherwise…

Question 15

Using Tools Model

Answer 15

Hands needed to be
free to make and use
tools to hunt . . .
But, don’t find evidence of
stone tools until long after
bipedalism

Question 16

Thermoregulatory model

Answer 16

Reduced heat gain
* Increased heat loss.

But, lots of
quadrupedal
animals in
savannas

Question 17

Climbing Mechanical Model

Answer 17

Retention of suspensory
morphology

• Perhaps arboreal habitat
  became patchy and arboreal
  ancestors had to travel on
  the ground and had to walk
  bipedally because of their
  morphology

Question 18

WHAT CAUSED NATURAL SELECTION TO ACT ON THIS TYPE OF LOCOMOTION?

Answer 18

We have no clue!

Question 19

general characteristics of
early hominins

Answer 19

• Bipedal
• Slightly increased cranial capacity (brain
  size)
• Trend toward non-honing premolars

Question 20

What is a honing pre-molar?

Answer 20

pre-molar that sharpens upper canine

Question 21

What are the 4 earliest known hominins?

Answer 21

o Sahelanthropus tchadensis
o Orrorin tugenensis
o Ardipithecus kadabba
o Ardipithecus ramidus

Question 22

Sahelanthropus tchadensis

Answer 22

Found In Chad
live = 6-7 million years ago
Had a premolar
became non honing
Was bidepal
a biforemagnum

Question 23

Orrorin tugenensis

Answer 23

Kenya
6.2-5.8 million years ago
Bipedal because of femur
reduce canine premolar
less honing

Question 24

Ardipithecus kadabba

Answer 24

Ethiopia
5.5-2 million years ago
Long toes
3rd premolar honing molar

Question 25

Ardipithecus ramidus

Answer 25

4.8 – 4.4 Ma Premolar less honing than in Ar. kadabba – Bipedal, but has a divergent big toe – Really long fingers