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Human Biology > Chapter 16-20 > Flashcards

Chapter 16-20 Flashcards

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1
Q

Define fossil

A
  • anything that is evidence of life that lived long ago

- any preserved remains/traces of organisms

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2
Q

General ways fossils are formed (4)

A
  • drifting sand
  • mud deposits (river)
  • volcanic ash
  • buried by another organism (burial)
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3
Q

What are fossils generally made of? why/how do they consist of these materials?

A

limestone
ion oxide
- flesh rots away leaving a cast - minerals are deposited into the poor replacing the organic material
- becomes petrified and turned to rock

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4
Q

Define petrified

A

Organic material that has turned into stone by replacing

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5
Q

What are the (4) conditions for a fossil to be formed?

A
  1. buried quickly - to delay decay and deposits
  2. alkaline soils - ideal, means that minerals in bone don’t dissolve
  3. lack of oxygen - oxygen needed to decompose
  4. hard body parts
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6
Q

General (3) locations for fossils

A
  1. edge of lakes, rivers - build up of sediments from flooding/flowing water over fossil to bury it
  2. caves - limestone containing of calcium carbonate - collapsed roof eg
  3. ash - volcanic eruptions which burry humans/animals
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7
Q

Name of ppl who discover fossils

A

anthropologists

- find fossils of artefacts (tools, beads, carvings…)

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8
Q

List 4 types of absolute dating

A
  1. potassium-argon dating
  2. carbon-14 (radiocarbon) dating
  3. Accelerator mass spectrometry (AMS) radiocarbon dating
  4. Dendrochronology (tree-ring dating)
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9
Q

Potassium-argon dating use and description (what/process)

A
  • volcanic rock only
  • Isotope - different forms of the same element with different neutron numbers in nucleus of atoms
  • potassium (K) - mixture of three different forms with different atomic weights
  • isotope potassium-40 is radioactive and decays at a fixed rate - forms carbon-40 and argon-40
  • determining amount of potassium-40 and argon-40 - can calculate age
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10
Q

Limitations/restrictions/conditions for potassium-argon dating

A
  1. only volcanic rock
  2. older than 100,000-200,000 years - anything younger would have too little decay to determine
  3. require suitable rock of same age as fossil to be found
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11
Q

Carbon-14 (radiocarbon) dating use and description (what/process)

A
  • is the decay of the radioactive isotope (carbon-14 to nitrogen)
  • young samples
  • organic materials
  • carbon-14 is produced in upper atmosphere where by cosmic radiation, turns to nitrogen at same rate it decays
  • plants take in carbon (1 carbon-14 for every million -12) and animals eat plants
  • when dead, -14 decays at a fixed rate, no more is taken in
  • HALF LIFE - decays to half the amount after 5730 years)
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12
Q

Limitations/restrictions/conditions for Carbon-14 (radiocarbon) dating

A
  1. younger samples
  2. up to 60,000-70,000 years
  3. 3g at least
  4. organic material
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13
Q

Accelerator mass spectrometry (radiocarbon) dating use and description (what/process)

A
  • more refined
  • dates small samples - as small as 100 micrograms
  • breaks up sample into its atoms so they can be counted
  • for cave paintings eg - pigments, honey, charcoal, oil, blood
  • for artefacts - tools, fire charcoal
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14
Q

Limitations/restrictions/conditions for Accelerator mass spectrometry (radiocarbon) dating

A
  • very small fossils
  • 100 micrograms +
  • recent - younger than 60,000 years
    must contain carbon - organic material
    -14, -12 ratio is not constant
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15
Q

Dendrochronology (tree-ring dating)

A
  • Using tree rings to determine years
  • Each ring represents one years growth
  • Rings vary in width compared to favourability of growing season
  • Correlate marker rings with timber taken from ancient human structures - determined age of these human structures
  • Small sample drilled from trunk and counting rings
  • Combined by radiocarbon dating
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16
Q

Dendrochronology (tree-ring dating) limitations/restrictions/conditions

A
  • Only determine age of tree/wood
  • Timber is rarely preserved for more than a few thousand years
  • Necessary conditions rarely occur
  • Up to 9000 years old
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17
Q

List 3 types of relative dating methods

A
  • fluorine dating
  • phylogenetic trees
  • stratigraphy
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18
Q

What is stratigraphy

A
  • study of layers of strata
    1. Principe of superposition - assuming that top layers are youngest - are complications though
    2. Correlation of rock strata - matching layers of rocks from different areas - examining rock itself first then fossils in it
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19
Q

Define index fossil

A

widely distributed - on earth for a limited period of period

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20
Q

Materials found with stratigraphy

A

bones, teeth, petrified wood/log, coral, insects, trilobite

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21
Q

Limitations of stratigraphy

A
  • Natural disasters - tsunamis
  • Earth plate movements
  • caution because sometimes layers are turned upside down - sometimes humans or animals are buried after deposition - may actually be younger than layers above
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22
Q

What is fluorine dating

A
  • When bone is left in soil, fluoride ions present in the water in the soil, replace the ions in the bone
  • The older the fossil, the more fluoride it contains
  • Not absolute because fluoride in water in soils varies from place to place
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23
Q

Define binomial system

A
  • use generic (genus) and specific (species) name
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24
Q

Define

A

evolutionary trends - gradual change in characteristics that occurred as primates became more highly evolved

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25
Q

Define hierarchy

A
  • series of groups of species from broad to specific

- divided into orders/ groups known as phyla

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26
Q

2 types of primates

A

primitive and anthropoids

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27
Q

Define arboreal

A

living in a tree environment

28
Q

List 8 general characteristic of all primates

A
  • BODY - not specialised for anything particular
  • LIMBS - unspecialised
  • HANDS/FEET - pentadactyl (five fingers), nails instead of claws, prehensile (grasp), first digit opposable,
  • EYES - 3D, forward facing, colour
  • SMELL - poor
  • TEETH - four incisors in upper and lower jaw
  • BRAIN - large and complex, cerebrum size is larger
  • REPRODUCTION - not restricted to a breeding cycle, rhythmic sexual cycle - month, year, One offspring at a time , Long period of parental care
29
Q

List 5 evolutionary trends (NOT for erect posture)

A
  • digits, dentition, smell, vision, brain, gestation/development
30
Q

Digits - list 6 evolvements

A
  1. pentadactyl
  2. prehensile
  3. opposability
  4. nails
  5. friction ridges
  6. precision grip
31
Q

Describe ‘prehensile’ as a trend

A
  • grasping fingers

- Evolutionary trend is to be able to move them freely of each other

32
Q

Describe opposability as a trend

A
  • thumb can touch each finger - longest in humans
  • Toe is opposable in primates – BESIDES humans - lost due to weight baring
  • Degree varies between species
33
Q

Describe nails as a trend

A
  • shorter and flattened instead of claws
  • Secure grip on trees
  • Better grip on objects
  • Some have single claw - toilet claw for scratching
  • Receptors on tips
34
Q

Describe friction ridges as a trend

A
  • small pads with tiny ridges/folds to increase grip
35
Q

Describe precision grip as a trend

A
  • only in humans
  • For holding pencils and sewing etc
  • Precise, delicate movement
36
Q

List 5 dentition evolvements

A
  1. change in dental formula
  2. dental comb
  3. number of teeth
  4. diastema
  5. cusps
37
Q

Describe dental forumula as a trend

A
  • number of each type of tooth
  • Primitive mammals - 3:1:4:3 (3 incisors, 1 canine, 4 premolars, 3 molars) - Total of 44 teeth
  • 36 teeth in lemurs, lorises and new world monkeys
  • Human teeth - 2:1:2:3
  • Total of 32 teeth
38
Q

Describe ‘number of teeth’ as a trend

A
  • Decrease in number of teeth - smaller face/head

- Large, sharp, pointy canines in old world monkey - humans are similar to other teeth

39
Q

Describe diastema as a trend

A
  • human don’t have anymore - change I diet and survival requirements
  • gap between large upper and lower canines
  • makes room for large incisors
  • Premolar slants to give room for large incisors
40
Q

Describe cusps as a trend

A
  • evolve from 3 cusps to 4 in top molars (+ shape)
    5 cusps in humans now
  • 5 cusps in lower molar (Y shape)
  • Evolved due to change in diet - fruits
  • Layer of had enamel covering teeth for protection from decomposition
41
Q

Describe dental comb as a trend

A
  • horizontal tooth bottom for grooming

- has disappeared now

42
Q

List and describe 4 trends in vision

A
  1. olfaction - decreased smell segment and increase emphasis on vision section in brain
  2. Stereoscopic vision - eyes at from of head - moved forward
    - was mandatory when arboreal - judge distance between trees
  3. Eye socket - become enclosed to protect the larger nerve
  4. Rods and cones - night vision and colour - Improved nerves between rods, cones, and brain
43
Q

Discuss ‘relative size of cerebral cortex’ as an evolutionary trend

A
  • increased in size
  • SIZE, CONVOLUTIONS, CEREBRAL SIZE
  • Involved with higher functions - vision, memory, reasoning…
  • Human average size - 1350cm3
  • Larger brains in primates for;
  • coordination as arboreal
  • Special/social skills
  • Finding food
  • Identifying threats
  • Larger and rounder with bigger brain and intelligence
  • Convolutions - stronger pattern/more in humans
44
Q

Discuss ‘Gestation and parental care’ as a trend

A
  • Increased length between fertilisation and brith
  • Increasing length that offspring is dependent off parent
  • sexual maturity increasingly later development
45
Q

State name for walking stance /motion

A

upright bipedal locomotion

46
Q

Define tribe

A

given to relatively new level of classification

47
Q

Brief order of primates (5) oldest to youngest

A
  1. Australopithecus africanus
  2. Australopithecus afarensis
  3. Homo erectus - standing upright
  4. Homo neanderthalensis
  5. Homo sapiens - humans
48
Q

List 8 adaptations/trends for erect posture

A
  1. foramen magnum
  2. curvature of the spine
  3. jaw
  4. pelvis
  5. carrying angle
  6. knee
  7. foot
  8. centre of gravity
49
Q

Compare the foramen magnum position / neck between apes and humans as a adaptation for erect posture

A

APE

  • sits at back of skull - horizontal stance
  • have large, strong neck/muscles to carry/support head

HUMANS

  • sits in the centre of the bottom of the cranium
  • in line with centre of gravity
  • supported by vertebrae column
  • has gradually moved forward because of erect posture
50
Q

Compare the curvature spine between apes and humans as a adaptation for erect posture

A

APE

  • flat, slight curved spine
  • straight
  • head protrudes off

HUMAN
- double curvature (two curves)
- S - shape
- CTLS / “STILTS” - cervical, thoracic, lumbar, sacral
- wedge of the lumber gives from froward to back - gives jutting curve
^ enables balance on neck
- brings vertical column directly under centre of gravity of skull

51
Q

Compare the jaw between apes and humans as a adaptation for erect posture

A

APE

  • protruding
  • large size
  • U shape

HUMAN

  • flatter facial profile
  • to balance head in the centre - so that head isn’t sticking out front/back more
  • parabolic shape
52
Q

Compare the pelvis between apes and humans as a adaptation for erect posture

A

APE

  • elongated
  • narrow
  • consists of scrum, acetabulum, pelvis

HUMAN

  • broader and shorter
  • bowl shaped
  • supports abdominal organs
  • larger in women for passageway in birth
  • space for bone and muscle attachment
53
Q

Compare the carrying angle between apes and humans as a adaptation for erect posture

A

APE

  • swayed walking
  • acetabulum in light with inner knee joint

HUMAN

  • tip of hip joint (hook) is directly above the centre of the knew joint - so busy weight can be transferred from pelvis to leg
  • wider acetabulum = femur converges towards inside
  • weight falls on outside of knee
  • centre of gravity crosses over femur
  • striding gate - hips and knee can be fully extended
54
Q

Compare the knee between apes and humans as a adaptation for erect posture

A
  • knee is a hinge joint with ligaments on either side
  • centre of gravity is in line with front of knee and down the outside
  • therefore force is trying to pull knee back but ligaments restrict bending in opposite direction
    = hinge wants to bend forward - force wants to bend back = equals out for no energy
55
Q

Compare feet between apes and humans as a adaptation for erect posture

A

APE

  • able to grasp with foot
  • opposability of big toe
  • lower down and smaller big toe - not as big and important as humans for balance

HUMAN

  • lost prehensility (grasping)
  • big toe is large and aligned with others - for balance
  • metatarsals for arch’s -longitudinal (front to back) and transverse arch (side to side)
56
Q

Compare centre of gravity between apes and humans as a adaptation for erect posture

A

APES

  • longer arms than legs - brings upper body down/slouched
  • higher centre of gravity - chest region

HUMAN

  • longer legs - concentrates gravity, increases length of stride/steps
  • lower centre of gravity - hips/pelvis
57
Q

Describe muscle tone in 3 areas

A
  1. striding gate - weight transferred from heel, along outside, crossing the ball and finishing at big toe
    - foot is now weight baring not gripping
  2. arm swinging - compensates for trunk rotations around pelvis
    - Right arm swings at left step etc.
    - Reduced energy expended
  3. carrying angle - weight distribution towards central axis
    Rotation of body at lower leg and foot - each footstep is more straight
58
Q

Describe relative size of cerebral cortex as an evolutionary trend

A
  • 1350cm3 - average human
  • frontal lobe in humans is very large - think, planning, processing, reasoning
    ^ functions that don’t occur hugely in app
  • absence of forehead in apes & protruding brow bone
  • cranium capacity measures brain size by endocasts
59
Q

Prognathism & dentition as an evolutionary trend - APE VS HUMAN

A

APE

  • protruding canines which are large and pointy
  • dental arcade = U - shape
  • diastema
  • 2:1:2:3
  • large brow ridge - instead of frontal lobe

HUMANS

  • small canines - look like incisors
  • parabolic shape
  • 2:1:2:3
  • small brow ridge
60
Q

List 5 advantages of bipedal locomotion

A
  1. increase range of vision - food/predators
  2. increase in height - scaring predators
  3. hands free for carrying (food)
  4. higher reach
  5. improved body cooling
61
Q

Why was there evolution from ape to bipedal locomotion/erect posture? (general)

A
  • cooling
  • 5 survival advantages
  • change in climate
  • change in environment - thinning of forests etc
  • avoid over heating - less sun contacts with vertical stance
62
Q

Australopithecine first fossil origin and time period

A

Southern Africa

Early 1920s

63
Q

Australopithecine - first noticeable changes (8)

A
  1. brow ridge / lower forearm head
  2. rounder head
  3. less protruding jaw
  4. . less protruding teeth
  5. foramen magnum moving forward
  6. bipedal locomotion
  7. canine
  8. pelvis/femur
64
Q

Name/ briefly describe two variants of australopithecines

A
  1. robust - taller and heavier
    - large, broader molars & jaw
    - bony crests in skull
  2. Gracile - shorter, lighter
    - proportioned head & jaw
    - Australopithecus afarensis and Africanus
65
Q

What is the other name for homo habilis - why that?

A

handyman

66
Q

Features of homo habilis (5)

A
  1. larger brain
  2. smaller teeth
  3. taller
  4. stood more erect
  5. powerful grasp- still spent time in trees

Human Biology (2 decks)

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