Anatomy changes - quadraped to biped

Question 1

Feet

Answer 1

Changes
- Opposable big toe to big toe in line
- Flat foot to arched foot
Reason
- Linear motion, absorbs shock of bipedal motion
- More efficient

Question 2

Spine

Answer 2

Changes
- Curved C-shaped spine to S-shaped spine
Reason
- Absorbs shock of bipedal motion, acting as a spring

Question 3

Pelvis

Answer 3

Changes
- Long and narrow to short and wide
Reason
- Supports organs above, allows for a bigger head, provides better muscle attachment and balance for bipedalism

Question 4

Knee

Answer 4

Changes
- Femur has become buttressed
- Femur attached to knee vertically now angled to lower leg (increased valgus angle)
Reason
- Support of vertical mass (down on knee joint)
- Allows better weight distribution, balance and more efficient locomotion

Question 5

Arms

Answer 5

Changes
- Long arms to short
Reason
- No longer needed for brachiating

Question 6

Cranial capacity

Answer 6

Changes
- 450cc to approx 1450cc
Reason
- Increased brain development - could be due to tool use, better developed hunting techniques etc.

Question 7

Skull changes

Answer 7

Changes
- Loss of sagittal crest
- Decreased jaw size
- Decreased zygomatic arch
- Smaller teeth and jaw size
- Loss of brow ridge
Reasons
- More refined diet, no need for strong chewing muscles, muscle attachment points or teeth

Question 8

Nuchal crest and foramen magnum

Answer 8

Changes
- Loss of nuchal crest
- Foramen magnum shifted to the centre of the skull
Reason
- Bipedalism, head verticle on spine and less muscle attachment needed

Question 9

Broca’s and Wernicke’s areas

Answer 9

Changes
- Appearance of these areas
Reason
- Used for language - production and comprehension

Question 10

Cerebral cortex

Answer 10

Change
- More folding
Reason
- Related to ‘higher order’ functions such as memory, attention, language etc. developed as a social structure allows more time, ie. hands free to carry out tasks

Question 11

Cerebellum

Answer 11

Change
- More developed
Reason
- Balance, coordination and tool use

Question 12

Hand

Answer 12

Changes
- Thumb more elongated and opposable
- Curved and long fingers to shorter and straight fingers
Reason
- No longer need to grip branches to brachiate
- Precision grip important for tool use

Question 13

Biological evolution definition

Answer 13

biological evolution refers to the changes in heritable characteristics such as skeletal and endocrnial changes occurring through genetic change and the transmission of DNA from one generation to the next

Question 14

AA of bipedalism

Answer 14

More efficient locomotion - energy and time efficient that favoured long distances
Seeing over tall grass - spotting predators and prey
Thermoregulation - less surface area exposed to heat with less trees so cooler
Freeing hands - can do other functions such as using tools and carrying offspring and food

Question 15

Disadvantages of bipedalism

Answer 15

Narrowed birth canal = harder childbirth
Flat feet = pain walking
Slipped discs in spine due to S shape making us more prone to damage