chapter 19 - human ancestors

Question 1

describe characteristics of australopithecus gracile (africanises / afarenses)

Answer 1

• 3-3.6 million (southern africa), slender
• 480 cm3 (brain)
• thumb is shorter less mobile, bigger heavier fingers, powerful
• projecting jaw, large canines, thick molars, vegetarian, no diastema
• low forehead, no sagittal crest, brain development, more rounded skull
• foramen magnum more forward
• s shaped curve
• more like human pelvis, underdeveloped striding gait
• carrying angle evident
• longitudinal arch, big toe parallel, strong big toe not prehensile

Question 2

describe characteristics of paranthropus robustus

Answer 2

• 1-2 million (southern africa), head build
• 480 cm3 (brain)
• greater precision grip, bigger molars, large jaw, brow ridge, low forehead, vegetarian, small incisors / canines
• sagittal crest present

Question 3

describe characteristics of homo habilus

Answer 3

• 1.75 million (western and southern africa)
• tool / handy man (oldowan)
• 775 cm3 (brain)
• molar and premolars smaller and narrower, flat nose brow ridge
• no sagittal crest, increased awareness of surrounding and reasoning (FL)
• ate more meat
• more of skull behind foramen magnum
• stood more erect (striding gait)

Question 4

describe characteristics of homo erectus

Answer 4

• 1.5 million - 200000 years (left africa, asia, europe indonesia)
• 1075 cm3 (brain)
• fire, shelters, hand axe (acheulian)
• noticeable forehead, flatter face (brain expansion), decrease pragmatism / jaw, thick brow ridge
• increased convolutions, FL, cranial capacity
• no chin, occipital bun rounded
• shorter toes like humans

Question 5

describe characteristics of homo neanderthals

Answer 5

• 250 000 - 300 000 years (europe, asia, north africa)
• 1485 cm3 (brain)
• ice ages (adapted to harsh climate), shorter limbs
• rounded skull, nose projected more than modern humans, very large brow ridge, large teeth
• prominent forehead, strong muscles
• wider pelvis, larger joints
• legs are 1/2 body, centre of gravity further up at pelvis
• larger calcaneus bone

Question 6

describe characteristics of homo sapiens (cro-magnum)

Answer 6

• 100 000 - present (africa, west asia, europe, global)
• 1350 cm3 (brain)
• only opposable thumb, precision grip well developed, decrease in power grip, less brow ridge, flat facial profile, smaller jaw, shorter snout, non-projecting canines
• separated eye socket, increased convolutions (50%), chin developed
• foramen magnum central under skull, no large neck muscles
• double curvature, forward jutting curve
• broad, short bowl shaped pelvis
• lost prehensility of foot, longitudinal and traverse arch, large calcaneus / tallis bone
• hips / knee fully straightened

Question 7

reasoning for locomotion

Answer 7

• free hands: carry food, tools, offspring
• increased visibility: detect prey / predators at greater distance
• increased size (deter predators)
• higher reach (picking fruit)
• thermoregulation: decrease SA to sun if standing upright (increases cooling)

Question 8

what changed in the environment

Answer 8

• 5-6 million years ago
• woodlands / forests became open grasslands
• temperature dropped (killed trees and food)

Question 9

summarise when major changes of digits, dentition / prognathism, skull / cranium, FM and S shaped curve, pelvis, knee / CA / COG and foot occurred

Answer 9

• digits: homo habilus and neanderthals
• dentition / prognathism: homo erectus and neanderthals
• skull / cranium: homo habilus and neanderthals
• FM / S: australopithecus
• pelvis: australopithecus
• knee / CA / COG: australopithecus and homo habilus
• foot: australopithecus and homo sapiens