Primate Evolution

Question 1

What are primates?

Answer 1

Primates have retained many mammalian traits. Primates are generalists. They are not specialized for a particular environment.

Question 2

List 5 general characteristics of primates.

Answer 2

1. Erect posture.
2. Prehensability in the hands and feet.
3. Forward facing eyes.
4. Longer lifespan and slower maturation.
5. Flexible and general limb structure.

Question 3

Describe the evolution of digits. (5)

Answer 3

1. Increase in mobility.
2. Increased ability to move digits independently.
3. The first digit has become opposable.
4. The first digit has increased in length.
5. Claws gave way to nails.

Question 4

Define prehensile.

Answer 4

Grasping refers to the digits of a hand or a foot that can grasp an object.

Question 5

Define opposability.

Answer 5

This means that the first digit can be moved in such a way that it can reach the other digits.

Question 6

Define precision grip.

Answer 6

The grasping of an object between the thumb tip and fingertip.

Question 7

What is an example of a precision grip?

Answer 7

Writing or holding a pencil.

Question 8

Define power grip.

Answer 8

The force applied by the fingers and thumb towards the palm to transmit force to an object.

Question 9

Describe the evolution of dentation. (6)

Answer 9

1. There has been a reduction in the number of teeth (36 to 32)
2. Increased number of cusps on premolars and molars (4 to 5)
3. Monkeys and apes have large projecting canines with diastema.
4. The diastema has been lost in humans.
5. Jaw has become more parabolic.
6. Tooth size has decreased leading to a flatter face.

Question 10

What is the diastema?

Answer 10

A gap in a row of teeth. It usually refers to a gap next to the canine teeth in primates.

Question 11

Describe the evolution of the sense of smell. (4)

Answer 11

1. Reduction in olfaction.
2. Reduction in snout length.
3. Reduced prognathic jaw.
4. Increasingly flat face.

Question 12

Describe the evolution of vision. (5)

Answer 12

1. Increasingly forward-facing eyes.
2. Increased efficiency of eyes.
3. Increased protection of eyes by bony sockets
4. Increased visual area in the brain.
5. Increased stereoscope vision (overlap and depth deception)

Question 13

Describe the evolution of the brain. (5)

Answer 13

1. Increase in size.
2. Increase in convolutions.
3. Increased size of the cerebral cortex.
4. Increased size of the cerebrum.
5. The frontal lobe has experienced the greatest enlargement in surface area.

Question 14

Describe the evolution of gestation and development. (2)

Answer 14

1. Increased length of time the offspring depend on the parents.
2. Increasingly later arrival of sexual maturity.