human evolution

Question 1

What did the diet of chimpanzees mainly comprise of? And how did this affect their facial structure?

Answer 1

Tough fibrous plant material so required powerful chewing forces generated by large muscles

Question 2

What selection pressure resulted in quadrepeds moving to bipeds?

Answer 2

Climate change - Africa became cooler and drier, reduced forestation to more grasslands, deserts and savannah ecosystems.

Climbing biped was advantageous as they could live in both habitats and occupy a wider niche. Gather more food, less competition for resources (outcompete other species that cannot carry out bipedalism), increase chances of survival and reproductive success

Question 3

Changes in hallux (big toe)

Answer 3

Q: opposable hallux to allow grasping during tree climbing, aid arboreal lifestyle

B: hallux in-line and non-opposable, provides forward thrust for bipedalism and aids with balance

Question 4

Changes in feet

Answer 4

Q: flat foot

B: arched foot, acts as a shock absorber and spring to propel forward

Question 5

Changes in foramen magnum

Answer 5

Q: positioned back of the skull, positions head forwards when moving quadrupedally

B: centralised, head balanced on top of spine over the centre of gravity so less energy required to support the head

Question 6

Changes in spine

Answer 6

Q: C-shaped spine, weight of abdomen supported on arched spine while on four limbs

B: S-shaped spine, acts as shock absorber, centre of gravity positioned above pelvis so less energy to support head

Question 7

Changes in ribcage

Answer 7

Q: cone shaped, house large gut and allow wide range of motion for brachiation

B: barrel shaped, allow arms to swing side to side to assist with balance when walking

Question 8

Changes in pelvis

Answer 8

Q: narrow and flat

B: shorter and broader, bowl shaped, allows for bigger head during birth

Question 9

Changes in valgus angle

Answer 9

Q: large valgus angle

B: smaller valgus angle, places feet directly below centre of gravity, allows for stable bipedal locomotion and conservation of energy whilst standing

Question 10

Changes in arm:leg ratio

Answer 10

Q: longer arms for brachiation

B: longer legs to cover more ground per stride, travel longer distances and increase energy efficiency

Question 11

Changes in fingers

Answer 11

Q: longer curved fingers, stronger grip on branches

B: shorter straight fingers, increases ability for power and precision grips for tool making

Question 12

Explain the selection pressure for finer motor control and precise manipulation of objects

Answer 12

More developed hand/wrist muscles have an adaptive advantage → create more sophisticated tools → more sophisticated hunting techniques → larger success rate of collecting food → greater chance of survival

Positive feedback loop between bipedalism and hand dexterity.

Question 13

What are the four changes to the endrocranium?

Answer 13

1. Increase in brain size
2. Increase in cortical tissue (cerebrum)
3. Increase infolding of cerebellum
4. Development of Broca’s and Wornicke’s areas

Question 14

Why is an increase in brain size good?

Answer 14

Tool making abilities increase → improved hunting efficiency → greater food supply and resources for a larger brain

Question 15

What is the cortical tissue (cerebrum) responsible for?

Answer 15

Higher brain function (abstract thought, finer motor control, complex thinking and actions)

Question 16

What is the cerebellum responsible for?

Answer 16

Balance and muscle coordination

Question 17

What are the Broca’s and Wornicke’s areas responsible for?

Answer 17

Broca’s = production of speech
Wornicke’s = comprehension of speech

Question 18

Why are the Broca’s and Wornicke’s areas beneficial?

Answer 18

Increase speech and language ability → improve communication → greater efficiency during group hunting + elders can pass down knowledge and experience to younger ones

Question 19

What are the 4 advantages of bipedalism?

Answer 19

Hands free → able to carry items eg. young or bring food back to home base + make tools

More energy efficient locomotion
- travel longer distances → outcompete other primates for resources
- more energy available for other activities

Easier to locate food and predatorss (disadvantage easier to be seen by predators)

60% less surface area exposed to the sun + stronger air currents above ground → keep cool → better thermoregulation on hot African grasslands

Question 20

What are the 6 disadvantages of bipedalism?

Answer 20

1. Childbirth is a risky process
2. Increased chance of hernias
3. Back ache + slipped discs (S-shaped spine → larger load on lower back)
4. Strain standing on two legs → arched feet collapse
5. Varicose veins (veins become enlarged and twisted) → susceptible to cuts and grazes

Reduced ability to travel distances + decreased speed (painful) → gather less resources for survival + increased chance of predation

Question 21

Biological evolution

Answer 21

The transmission of genetic material from parent to offspring

Question 22

Cultural evolution

Answer 22

The change in human culture through the transmission of learned behaviour, ideas and knowledge from one generation to another

Question 23

What trend did tools show over time?

Answer 23

• more specialised
• sharper, more refined, longer blades
• increase in variety and quality of materials
• more complex, more imagination
• more blows/strikes

Question 24

Oldowan tools (who, how many blows, description)

Answer 24

Homo habilis
~ 6 blows
Stone tools with several flakes knocked off one side by heavy blows by another rock

Question 25

Acheulian tools (who, how many blows, description)

Answer 25

Homo erectus ~ 50 blows Stone tools with flakes struck off both sides (biface), long sharp edges

Question 26

Mousterian tools (who, how many blows, description)

Answer 26

Homo neanderthalensis ~ 150 blows Levallois technique used to sharpen flakes Specialised tools eg. spears and axes

Question 27

Upper Paleolithic tools (who, how many blows, description)

Answer 27

Homo sapiens ~ 250 blows Specialised, finer and composite tools Huge range of tools, very job specific

Question 28

What are the 5 advantages of tools?

Answer 28

1. Skin animals for clothes and shelter → live in cold places/new environments + less sickness 2. Hunt bigger animals → more meat/energy 3. Access to wider variety of food sources → higher quality diet eg. meat 4. Better able to manipulate materials → more complex shelters made → large groups to live together 5. Change in skull (don’t need big teeth/jaws) → increased brain size + cognitive ability

Question 29

Who was the first to use fire?

Answer 29

Homo erectus

Question 30

What are the advantages of fire?

Answer 30

1. Lengthens day (light source at night) 2. Cooking 3. Better weapons/tools 4.Protection from predators (scare predators away) 5. Provides warmth (migrate to colder areas)

Question 31

Why is longer day length provided by fire beneficial?

Answer 31

Enables activities to continue after dark -more time to make tools, learn language, teach others Time to socialise - binds group together for cooperation

Question 32

Why is cooking beneficial?

Answer 32

Soften foods and easier to chew → no need to grow large jaw/teeth/ muscles → energy can be used to run a bigger brain Detoxifies food and kills pathogens in meat → prevent illness and death Makes food more digestible → greater energy intake from same amount of food Preserve meat (smoking) → lower chance of starvation when food is scarce Poisonous foods when raw can be eaten when cooked → wider variety of food

Question 33

How does fire improve hunting?

Answer 33

Fire hardened spear tips → sharper Hunt with fire → stampede animals → more efficient and successful hunting → more food

Question 34

What are the disadvantages of fire?

Answer 34

Lots of energy to make May burn yourself Destroys ecology Attracts predators (beacon) Smoke/fire (tuberculosis)