human evolution Flashcards

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1
Q

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

A

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

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2
Q

What selection pressure resulted in quadrepeds moving to bipeds?

A

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

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3
Q

Changes in hallux (big toe)

A

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

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4
Q

Changes in feet

A

Q: flat foot

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

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5
Q

Changes in foramen magnum

A

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

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6
Q

Changes in spine

A

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

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7
Q

Changes in ribcage

A

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

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8
Q

Changes in pelvis

A

Q: narrow and flat

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

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9
Q

Changes in valgus angle

A

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

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10
Q

Changes in arm:leg ratio

A

Q: longer arms for brachiation

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

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11
Q

Changes in fingers

A

Q: longer curved fingers, stronger grip on branches

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

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12
Q

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

A

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.

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13
Q

What are the four changes to the endrocranium?

A
  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
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14
Q

Why is an increase in brain size good?

A

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

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15
Q

What is the cortical tissue (cerebrum) responsible for?

A

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

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16
Q

What is the cerebellum responsible for?

A

Balance and muscle coordination

17
Q

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

A

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

18
Q

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

A

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

19
Q

What are the 4 advantages of bipedalism?

A

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

20
Q

What are the 6 disadvantages of bipedalism?

A
  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

21
Q

Biological evolution

A

The transmission of genetic material from parent to offspring

22
Q

Cultural evolution

A

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

23
Q

What trend did tools show over time?

A
  • more specialised
  • sharper, more refined, longer blades
  • increase in variety and quality of materials
  • more complex, more imagination
  • more blows/strikes
24
Q

Oldowan tools (who, how many blows, description)

A

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

25
Q

Acheulian tools (who, how many blows, description)

A

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

26
Q

Mousterian tools (who, how many blows, description)

A

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

27
Q

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

A

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

28
Q

What are the 5 advantages of tools?

A
  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
29
Q

Who was the first to use fire?

A

Homo erectus

30
Q

What are the advantages of fire?

A
  1. Lengthens day (light source at night)
  2. Cooking
  3. Better weapons/tools
    4.Protection from predators (scare predators away)
  4. Provides warmth (migrate to colder areas)
31
Q

Why is longer day length provided by fire beneficial?

A

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

32
Q

Why is cooking beneficial?

A

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

33
Q

How does fire improve hunting?

A

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

34
Q

What are the disadvantages of fire?

A

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