Human Evolution

Question 1

The upper limbs

Answer 1

Primates have very large upper arms, which they can move freely. Primates can also rotate their forearms around the elbow joint.
Primates have flat nails instead of claws. Their bare finger tips are rich in nerve endings which make them very sensitive, allowing for precision work such as in making and using tools.
All primates have thumbs which work in the opposite direction to their fingers. We say that primates have opposable thumbs. The thumb can be pressed against the fingers, and the hands forming a power grip for grasping trees branches and climbing. Apes and humans can also use their fingers and thumbs in a precise grip such as holding a pair of tweezers.

Question 2

The brain

Answer 2

Primates have large brains compared to their body masses. This allows them to make sense of the large amount of information they obtain.

Question 3

Vision

Answer 3

The process of looking at an object with both eyes is referred to as binocular vision, observing the solid nature of an object is called stereoscopic vision. In addition, the eyes of primates have cones (as well as rods) for colour vision and greater clarity for vision.

Question 4

Summary of Similarities between African Apes and Humans

Answer 4

1. Large brains/ skulls compared to their body mass.
   Olfactory brain centers reduced/ reduced sense of smell.
   Parts of the brain that process information from the hands and eyes are enlarged.
2. Eyes in front/ binocular vision/ stereoscopic vision.
   Eyes with cones and rods/ colour vision.
3. Freely floating arms.
4. Long upper arms.
5. Elbow joints allows rotation of the forearm.
6. Flat nails instead of claws/ bare finger tips.
7. Opposable thumbs which work in opposable direction to their fingers.
8. Upright posture.