Evolution - Chapter 12

Question 1

Order (classification)

Answer 1

Primates - tarsiers, lemurs, lorises, monkeys, apes and humans

Question 2

Suborder (classification)

Answer 2

Haplorrhini - tarsiers, monkeys, apes and humans

Question 3

Infraorder (classification)

Answer 3

Simiiformes - monkeys, apes and humans

Question 4

Parvorder (classification)

Answer 4

Catarrhini - old world monkeys, apes and humans

Question 5

Superfamily (classification)

Answer 5

Hominoidea - apes and humans

Question 6

Family (classification)

Answer 6

Hominidae - Humans and great apes

Question 7

Subfamily (classification)

Answer 7

Homininae - all modern humans and extinct chimpanzees, gorillas and humans

Question 8

Genus (classification)

Answer 8

Homo - extinct humans and modern humans

Question 9

Species (classification)

Answer 9

Sapiens - modern humans

Question 10

Cerebrum size in lemurs vs humans

Answer 10

In primates, the cerebrum has progressively increased in size, lemurs = 24cm^3 and humans = 1350cm^3

Question 11

Frontal lobe in humans vs apes

Answer 11

In humans the frontal lobe makes up 47% of the total cortical surface vs apes it makes up 33%.

frontal lobe - higher functions of thinking, reasoning, planning and processing take place

Question 12

Convolutions in brains of hominids

Answer 12

have strong patterns of convolutions which enable surface area of brain to increase. they have results in a 50% increase in SA of human brain compared to without them.

• has effects on how primates live, e.g, tool making involves a predetermined image of what the completed tool should look like.

Question 13

How is cranial capacity found?

Answer 13

determined by measuring the volume inside the cranium using an enbocast.

Question 14

Pentadactyl

Answer 14

have 5 digits on each limb.
- highly mobile, which is a feature related to the arboreal way of life of primate ancestors.

Question 15

Prehensile

Answer 15

(grasping) refers to the digits of a hand or foot that can grasp an object - essential for climbing.

Question 16

Evolutionary trends towards increasing mobility

Answer 16

• thumb and big toe and highly developed in this respect
• they’re independent and opposable

Question 17

Opposability

Answer 17

the ability to use the thumb to touch the tips of each of the other digits on the hand.
- degree of opposability varies and depends on the length of the first digit compared with the other four.
- opposability was lost in the big toe when the human foot became a weight bearing rather than a grasping.
- having highly mobile digits has enabled humans to manipulate objects with great skill.

Question 18

Precision grip

Answer 18

the grasping of an object between thumb and fingertip, e.g, holding a pen when writing.

Question 19

Power grip

Answer 19

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

Question 20

Adaptations to locomotion

Answer 20

1. position of the foramen magnum
2. curvature of the spinal column
3. the jaw
4. the pelvis
5. the knee
6. the foot
7. centre of gravity
8. muscle tone
9. striding gate
10. advantages of bipedalism

Question 21

Position of the foramen magnum

Answer 21

The opening between the cranium through which the spinal cord passes.
- moved forward to become more central
- this allows the skull to balance on top of the vertebral column
- ape/gorilla - needs large neck muscles to hold head up
- in humans, the weight of the skull is borne by the vertebral column - so no large neck muscles necessary

Question 22

Curvature of the spinal cord

Answer 22

• curvature has changed to allow upright posture
• smooth ‘c-shaped’ curve has evolved to a ‘s-shaped’ curve in humans
• this improved body balance and enables head to balance on top of spine/neck
• humans have double curvature achieved by the lower vertebrae in lumbar region
• cervical curvature - brings vertebral column directly under centre of gravity of skull

Question 23

The jaw

Answer 23

• from ape-like ancestor, size and protrusion of jaw is reduced
• apes show prognathism (protruding jaw). humans have flatter facial profile mainly due to softer food, large jaw for chewing tough plant material not needed.
• change allows skull to balance on top of spine because weight in front of foramen magnum is equal to the weight behind.

Question 24

The pelvis

Answer 24

gorilla = taller, narrower pelvis and is a long shape

human = broader and shorter pelvis (from top to bottom.
- bowl shaped supports abdominal organs when standing, provides greater stability for bipedal walking and supports developing foetus during pregnancy.
- broad hip bone provides an attachment for large buttock muscles, important in leg movement and keeping upper body erect.

Question 25

The knee

Answer 25

• in bipedal species: weight of body transferred down the outside of the femur to the knee
• ## knee joint = 2 part hinge joint, with one hinge on either side of the cruciate ligaments in the middle of the joint. weight is transmitted to outer hinge