Human Evolution

Question 1

Fossil Evidence: Bipedalism

Answer 1

Bipedalism offers the animal the following advantages:
The hands become free for carrying food, tools and babies.
A better view of the surroundings.
Movement from place to place becomes more efficient.
Faster cooling of the body, which was essential in their original hot tropical environment.
Display of the male sex organ as part of courtship behaviour.

Question 2

Foramen magnum

Answer 2

The opening that allows the spinal cord to leave the skull (foramen magnum) must change from the back of the skull in animals that walk on all four legs (quadrupeds) to a forward position at the bottom of the skull in bipedal animals.

Question 3

Fossil Evidence: A Flat Face

Answer 3

Our faces appear flat because:
Our foreheads do not slope backwards as much s those of ape men.
Our lower jaws have a well-developed chin.
The bones of the nose and jaws do not stick out as much as those as ape men. i.e. we are not prognathous.

In addition to our flat faces, our brow and cranial ridges are not as pronounced as those of ape men.

Question 4

Fossil Evidence: Shape of Jaws

Answer 4

The jaws of apes are U-shaped with parallel sides and a slightly rounded front. The incisors are in front while the cranium, premolars and molars are on the sides.
The sides and front of human jaws are slightly curved.

Question 5

Fossil Evidence: Dentition

Answer 5

The oldest primates have the dental formula 1:2:3:3/ 1:2:3:3 whereas humans have the same dental formula as apes which is 2:1:3:3/2:1:3:3. However, humans have very small canines.

Question 6

Fossil Evidence: An enlarged brain

Answer 6

In primates, the ratio of the brain size to body mass is greater than in other organisms. Modern humans have the larger brain size of all primates.