hominid evolution Flashcards
(166 cards)
1
Q
order
A
Primates:
Primates include tarsiers, lemurs, lorises, monkeys, apes and humans
2
Q
Family
A
Hominidae
Hominids include all modern and extinct orangutans, gorillas, chimpanzees and humans
3
Q
Tribe*
A
Homini:
Hominins include extinct ancestors of humans and modern humans
4
Q
Genus
A
Homo:
Homo includes some extinct ancestors of humans and modern humans
5
Q
Species
A
sapiens:
Homo sapiens are modern humans
6
Q
are there a singular characteristic that can be used to separate the primates from all other mammals
A
no
7
Q
what are most features of a primate a result of?
A
having evolved in an arboreal, or tree-like, environment.
8
Q
primate characteristics: body
A
not specialised for a particular environment
9
Q
primate characteristics: limbs
A
Generally unspecialised
10
Q
primate characteristics: hands/feet
A
Pentadactyl - five fingers or toes
Nails instead of claws
Grasping fingers and toes with friction ridges for gripping
First digit opposable
11
Q
primate characteristics: eyes
A
Forward facing for three-dimensional (stereoscopic) vision
Most are able to distinguish colour
12
Q
primate characteristics: Sense of smell
A
Very poor
13
Q
primate characteristics: Teeth
A
Four incisors in both the upper and lower jaw
14
Q
primate characteristics: Brain
A
Large and complex
Cerebrum size increases as primates become more highly evolved
15
Q
primate characteristics: Reproduction
A
Not restricted to a breeding season
Rhythmical sexual cycle
Usually only one offspring at a time
Long period of parental care for offspring
16
Q
humans are in same family as?
A
great apes (orang, chimp, gorilla, bonobos)
17
Q
characteristics all species in the family Hominidae share
A
- larger, more complex brain than other primates → increase cognitive ability → recognise self in a mirror
- five cusps in the molar teeth of the lower jaw as diet was mainly fruit
- arms that can freely rotate at the shoulder
- wide, shallow chest cavity
- no external tail
- an appendix
- diurnal (active during the day)
18
Q
variations that reflect changes in the DNA nucleotide sequences during evolution
A
- relative size of the cerebral cortex
- mobility of digits
- locomotion – adaptions to bipedalism and quadrupedalism
- prognathism and dentition
19
Q
the cerebrum progressively ___________ in size
A
increased (especially cerebral cortex)
20
Q
change in cerebrum size results
A
- higher-order functions (vision, memory, reasoning, manipulative ability)
- necessary to cope successfully with environmental change
21
Q
why did primates have large brains for their body size
A
- due to tree dwelling environment
- pressure of natural selection in arboreal environ. → favoured more accurate visual and tactile perception, better coordination b/w sensory stimuli + muscular response
- reliance on vision to move, locate and manipulate food → large amount of complex sensory info to be processed and stored (carried out by cerebral cortex)
- pressure of natural selection in arboreal environ. → favoured more accurate visual and tactile perception, better coordination b/w sensory stimuli + muscular response
22
Q
apes average cerebral cortex size
A
b/w 400-500 cm
23
Q
which lobe had the greatest enlargement in surface area and why?
A
frontal lobe; higher functions – thinking, reasoning, planning
24
Q
Pattern of convolutions (folds) purpose
A
Enable surface area of brain to be increased
25
Effect on life of primates due to increase in size of CC
- Move around and locate food
- Develop social skills
- Tool making
- Involves predetermine image of what completed tool should look like (higher skill)
- Greater variety of behavioural responses to meet variety of problems
- Most primate species → daily life involves interactions with relatives, allies, adversaries
- Mutual cleaning and grooming → reinforce relationships
- Threats → lead to fighting → maintain hierarchy of dominance
- Behavioural flexibility taken place of further physical specialisation
26
was the Early hominin brain fossilised
no
27
endocast
an impression of the inside of the brain case, either artificial or natural, made of rock or some other solid material
28
purpose of endocast
determine brain size by measuring volume inside cranium using an endocast = cranial capacity
29
two areas of the brain have become highly developed in modern humans
- broca's area
- wernicke's area
30
broca's area
speech production
Controls the muscles of the lips, jaw, tongue, soft palate and vocal cords during speech
31
wernicke's area
comprehension of language - ability to listen
32
Pentadactyl
5 digits on each limb
33
Digits are highly mobile why?
related to arboreal way of life
34
why are prehensile digits essential?
essential for climbing, wrapping long curved digits around branches of trees
35
Evolutionary trend of the mobility of digits
increasing ability to move digits independently of one another
36
which digits were most highly developed
Thumb and big toe
37
Opposability
first digit can be moved in such a way that it can touch each of the other digits
38
what does opposability depend on
Depends on relative length of the first digital compared to other four
39
how did primates lose opposability
Lost opposability when human foot became weight bearing rather than grasping
40
precision grip
Humans have longest thumb of all primates → allows us to manipulate objects with our hands
41
quadrupedalism
walking on four limbs
42
bipedalism
walking on two legs
43
bipedalism is an adaptation that...
that helps human ancestors to survive → acted as a selective pressure during natural selection
44
Foramen magnum
where the brain joins the spinal cord through a hole in the skill
45
what happened to the foramen magnum due to evolution
Gradually moved forward to become more central (due to evolution of modern humans)
- Allows skull to balance of top of vertebral column
46
Gorilla foramen magnum position
needs large neck muscles to hold head in position
47
humans foramen magnum position
weight of skull is born by vertebral column→ large neck muscles not required
48
Curvature of the SC Evolution (structure)
Smooth C shaped curve (apes like gorillas) → evolved to S shaped curve (double curvature)
49
curvature of the SC Evolution results
allow upright posture
- Improves body balance in upright position
- Enable head to balance on top of neck
50
jaw for apes and humans
- Apes = protruding jaw (prognathism)
- Humans = flatter facial profile
51
evolution effects on the jaw
- Size and protrusion reduced due to evolution
- Allows the skull to balance on the top of the spine (weight in front of FM is = to weight behind it)
- Balanced achieved with min of muscular effort
52
humans pelvis structure
broader, shorter from top to bottom, bowl shaped
53
humans pelvis benefits
- Bowl shaped supports abdominal organs when standing erect
- Provides greater stability for bipedal locomotion
- Supports developing foetus during pregnancy
- Broad hip bones provide space for attachment of large buttock muscles → move legs; keep upper body erect
54
the carrying angle
shape and orientation of the pelvis → hip joint being directly under the trunk and head
55
what does the carrying angle allow for?
- Allows the weight of the body to be transferred from pelvis → legs
- Allows for greater stability in an upright posture
56
changes to femur due to evolution
- Head of femur is larger, fits into acetabulum of pelvis
- Pelvis is broad → hip sockets wide apart→ femurs converge towards knees
- Femur arrangement forms angle to the vertical = carrying angle
57
weight distribution due to changes to femurs
- Ensures the weight distribution remains close to the central axis of the body when walking
- Weight tends to fall through the outside of femur (reverse in apes)
58
what does walking enable?
- enables the body to be rotated about the lower leg and foot; each footstep follows a near straight line
- Allows humans to have a striding gait instead of swaying from side to side like gorillas or chimps when walking on two legs
59
knee adaptation
- Bipedal species = weight of body transmitted down outside of femur → knee
- Knee joint = two-part hinge joint
60
Natural resistance
produces a joint that requires no energy to support body in a standing position
61
Centre of gravity
Centre of gravity of body tends to fall through a line just in front of knees → results in force that tried to bend knee backwards but resisted by knee ligaments
62
how is body weight transmitted at the ankle
From knee joint, most of body weight transferred through tibia → ankle
BW transmitted from tibia through talus (ankle bone) → other tarsal bones → metatarsals → phalanges via arches of foot
63
Human foot distinctive adaptation for bipedal locomotion
- Lost its grasping ability/prehensibility – now a highly specialised locomotory organ
- Seen in big toe
- Metatarsals shapes to form two arches (enabled humans to perfect bipedal locomotion)
- Longitudinal arch (front to back)
- Transverse arch (side to side)
64
effects of humans having longer legs than arms
- Long legs increase length of stride when walking
- Serve to lower centre of gravity of body (point at which all the weight of the body appears to be concentrated) – pelvis level
- Contributes to stability when moving bipedally/standing erect
65
location of centre of gravity for apes and humans
apes: Higher centre of gravity (chest level)
humans: lower centre of gravity (pelvis level)
66
Muscle tone
partial contraction of skeletal muscles
67
muscle tone example
To keep the head, erect and stop it from slumping forward onto chest → muscles in back of neck are partially contracted (have tone)
68
Sustained muscle tone is evident in which muscles?
- muscles that support the body in an upright position
- Muscles in humans = those that bring about movement of the spine, hip, knee and ankle, Abdo muscles
69
Striding gait
walking upright in such a way that the hip and knee are full straightened
70
other apes gait
Even when walking on their hind legs – knees bent, and bodies bent forward at hips
71
Process of locomotion
- Foot hits ground → weight transmitted from heel along outside of foot as far as the ball, crosses the ball of the foot (via transverse arch) → borne by the big toe
- Final moment of striding = whole weight of body propelled by the big toe
72
Reason why hominins lost opposability of the big toe
human foot evolved into a weight-bearing appendage rather than grasping
73
Walking (rotation)
- trunk rotates about the pelvis
- forward swinging of the arms compensates for this natural rotation of the body: right arm naturally swings forward as the left leg is extended
- keeps shoulders at right angles to the direction of travel
- reduces amount of energy expended
- if arms didn’t move → energy wasted in reversing the rotation of the body after each stride
74
Advantages of bipedalism
- more energy efficient means of moving
- leaves hands free to use tools
- leave hands free to carry items e.g. food
- increased size deterring predators
- higher reacher when picking fruit from trees
- upright stance achieved greater height and thus the ability to see further for detecting predators
- upright stance means that less of the body is exposed to sunlight → less overheating
- upright stance increased exposure to breezes, increasing cooling mechanisms
75
primates: two sets of teeth
- deciduous (baby teeth)
- permanent
76
dental formula
number of each type of tooth that a species has
- gives the no. of each type of tooth in ¼ of jaw
77
primitive mammals: dental formula
44 teeth; 3 incisors, 1 canine, 4 pre-molars and 3 molars on each side of jaw
78
Old world monkeys, apes’ humans: dental formula
32 teeth; 2 incisors, 1 canine, 2 premolar, 3 molar
79
teeth - Natural selection
- decrease in no. of other in primates compared to early mammals
- Gradual reduction in the size of the face and jaw that has occurred in primates → allows skill to balance during bipedalism
80
Canines
- Canines are large and sharply pointed, projecting beyond level of other teeth
- Large canines have required modifications to adjacent teeth for mouth to close
- Most primates with large canines have a diastema (gap) b/w upper 2nd incisor and upper canine → accommodate the large lower canine
- Surface of molars have evolved → pattern useful in identifying teeth of fossil apes and humans
- Evolved due to predominantly fruit diet of apes (five cusps in molars)
81
distinctive human dentition
- Canine teeth don’t project beyond level of other teeth and interlock
- More even in size
- Small canine teeth and incisors take up less room in jaw
- Shape of tooth row or dental arcade has evolved into a different shape, instead of U shape of apes → parabolic in shape
82
timelines of human evolution
1. australopithecus afarensis
2. australopithecus africanus
3. paranthropus robustus
4. homo habilis
5. homo erectus
6. homo neanderthalensis
7. homo sapiens
83
how old is australopithecus afarensis
3.9 - 2.5 mya
84
brain size for australopithecus afarensis
375 - 500 cc
85
height: a. afarensis
1 - 1.5m
86
early discovery site: australopithecus afarensis
east africa, ethiopia
87
what two things are assigned to australopithecus afarensis
Lucy, The First Family, and the Laetoli footprints
88
diet: A. afarensis
herbivores (seeds, grains, fruit and roots)
89
skull: A. afarensis
- low forehead
- prominent brow ridge
- sagittal crest present in males
90
teeth and jaw: A. afarensis
- no chin
- prognathic jaw
- diastema
- small canine teeth
91
Limbs: A. afarensis
- non-opposable big toe
- long arms, shorter than legs
- long curved fingers and toes
92
pelvis: A. afarensis
- short and wide
- features of bipedalism
93
how old is australopithecus africanus
3.2 - 2 mya
94
brain size A. africanus
400-500cc
95
height: a. africanus
1 - 1.3m
96
early discovery site: A. africanus
South Africa
97
diet: A. africanus
omnivores
98
skull: A. africanus
- slightly arched forehead
- shorter face
- smaller brow ridge
99
teeth and jaw: A. africanus
- prognathic jaw
- shorter and smaller incisors and canines than a. afarensis
- parabolic tooth row
- no diastema
100
limbs: A. africanus
- non-opposable big toe
- long arms, shorter than legs
- some curvature of fingers and toes
101
pelvis: A. africanus
- short and wide
- features of bipedalism
102
how old is paranthropus robustus
2.5 - 1.5 mya
103
brain size: paranthropus robustus
~ 530 cc
104
height: paranthropus robustus
1.5 - 1.7 m
105
early discovery site: paranthropus robustus
South Africa
106
diet: paranthropus robustus
herbivores (berries, nuts, fruits, roots)
107
build: paranthropus robustus
heavy build
108
skull: paranthropus robustus
- long, broad, flat face
- sagittal crest
109
teeth and jaw: paranthropus robustus
- thick jaws (wide cheekbones)
- small incisors and canines
- large molar like premolars; large molars
110
limbs: paranthropus robustus
- long arms
- moderate sexual dimorphism
111
how old is homo habilis
2.4 - 1.5 mya
112
brain size: H. habilis
500 - 650 cc
113
height: H. habilis
1.2 to 1.5 m
114
early discovery sites: H. habilis
Eastern and Southern Africa
115
diet and food resources: H. habilis
omnivores -> scavengers, hunters/gatherers of catfish, small animals and plants
- diet largely carnivorous, small teeth with narrow back teeth
116
skull: H. habilis
- rounder skull
- central foramen magnum
- bulge in broca's area -> speech production
- smaller face than australo
- no sagittal crest
- flat nose
117
teeth and jaw: H. habilis
- evident prognathism
- modern curve (parabolic)
- smaller jaw than australo
- smaller, narrow molars
- reduced snout
118
limbs: H. habilis
- long arms
- human like feet and hands
- fully bipedal
119
how old is homo erectus
1.8 mya - 200,000
120
height: H.erectus
1.5m to 1.8m
121
brain size: H.erectus
850 - 1000 cc
122
early discovery site: H.erectus
Africa, Asia, Indonesia, possibly Europe
123
diet and food resources: H.erectus
omnivorous -> large groups hunting, largely carnivirous thus massive molars
- Systematic hunting of large game had become a major part of hominid life for the first time. (hunting = major source of food)
124
skull: H.erectus
- shelving forehead
- thick brow ridge
- swelling in the brain (broca's and wernicke's area for speech production and recognition)
- bun like swelling (not super prominent)
125
teeth and jaw: H.erectus
- no chin
- projecting jaw
126
physique: H.erectus
robust but "human" skeleton
127
how old is h. neanderthalensis
160,000 to 32,000 years
128
brain size: H. neanderthalensis
1400-1600 cc
129
height: H. neanderthalensis
1.5 - 1.7m
130
early discovery sites: H. neanderthalensis
europe and western asia (middle east)
131
diet and food resources: H. neanderthalensis
carnivores
These people were hunters.
- Plant food would have been seasonal and unavailable during the cold winter of the glacial period (Europe)
- Possess large molar teeth that are well worn.
132
skull: H. neanderthalensis
- heavy, double-arched brow ridges
- long low skull/long nasal opening
- sloping forehead
- prominent bun like swelling in occipital lobe
133
teeth and jaw: H. neanderthalensis
- smaller teeth than H erectus
- flared zygomatic arches
- weak chin
- larger teeth than h sapiens
- retromolar gap
134
body type: H. neanderthalensis
- shorter, more robust and muscular than modern humans (adapted for cold conditions)
- wider shoulders
135
limbs: H. neanderthalensis
- thick limbs with large joints
- shorter fingers and toes
136
pelvis: H. neanderthalensis
- wider pelvis
137
how old is homo sapiens
300,000 - present
138
brain size: H. sapiens
1350-1400cc
139
height: H. sapiens
1.65-1.85 m
140
early discovery sites: H. sapiens
africa and western asia -> WORLDWIDE
141
diet and food resources: H. sapiens
carnivores
- Exploited numerous food resources as a hunter-gatherer.
- Later a farmer with domesticated animals and cultivated crops.
- Teeth became smaller as food preparation improved.
142
skull: H. sapiens
- no brow ridge, just slight swelling of glabella
- vertical face
- high, vertical forehead
- occipital lobe is rounded and low
143
teeth and jaw: H. sapiens
- reduced teeth size
- sizable jaw with projecting chin
- reduced size of jaw and associated muscles
144
body type: H. sapiens
- short, slender trunks with long limbs
145
limbs: H. sapiens
- long legs compared with arms
- straight fingers and toes
146
which hominin was referred to as handy man
homo habilis
147
selection pressures for H. habilis
- Increases in brain size selected for
- Reduction in sexual dimorphism suggests that increased cooperation is required perhaps due to the adoption of hunting which requires numerous individuals working as a team
148
culture: homo habilis
- Tools made from materials some distance away which suggests that they 'planned' the manufacturing of tools in advance.
- Sharing of food b/w hunters and gatherers → development of communities → development of language
149
tool culture and use: homo habilis
**OLDAWON**
- Pebble tools fashioned from lava cobble.
- Other perishable tools also probably used.
- Choppers and scrapers,
associated with butchering animal bones
- Grinding tough plant
materials
- Digging up edible roots and plants
150
tool manufacture: homo habilis
tools were crudely, fashioned with few hammer blows (simple)
- Stone/pebbles/rocks with one or two pieces chipped off by striking/flaking rocks together/striking one stone with another
151
selection pressures: homo erectus
- A marked increase in brain size and complexity suggests that there were strong pressures for increased intelligence.
- Development of tool technology gives competitive advantage over other predators.
- Selection for improved bipedalism (occupy a range of geographical areas
152
culture: homo erectus
- More advanced tool making required an ability to plan the shape of the tool before it was made.
- Tool making had a specific purpose
- Some evidence of scalping which suggests that some form of ritualism existed.
- Evidence of modifying environment to suit needs
- Use of fire, building and
modifying
shelters, using range of tools
- Cultural changes
- Greater emphasis on cooperation (caring for young)
- Complex lang. dev
153
tool culture and use: homo erectus
**ACHEULIAN**
- Stone tools manufactured with more precision eg.
Hand axes (variety of sizes but using a similar shape for different tasks)
- Characteristic biface shape 'tear drop'.
- Tools tend to be large and unrefined.
- Development of tools linked to increased communication due to social learning
154
tool manufacture: homo erectus
- Shaping of whole stone to a particular design
- Bifaced - chipping from both sides
- Careful repetitive flaking
- Pressure flaking
155
selection pressures: homo neanderthalensis
- Well adapted to the cold glacial climate prevailing - with stout squat body form.
- Food supply was possibly tenuous at times.
- Having to cope with the cold by developing use of clothing, fire and shelters.
- Finally unable to cope with selection pressure of modern humans
(H.sapiens) and became extinct.
- Out competed directly (combat) or indirectly (through hunting and gathering same resources)
156
culture: homo neanderthalensis
- Individuals were buried on their sides with knees up around their chest, covered with acre or flowers, surrounded by skulls or horns → suggests the beginnings of religious ritual/ceremonies
- Cave bear cult involved some spiritual
appreciation of the cave bear.
- Used fire for warmth and cooking.
- Probably made clothing and blankets from animal skins
- Highly developed social system of sharing food and other resources
157
tool culture and use: homo neanderthalensis
**MOUSTERIAN**
- Use of caves as shelters by some groups, others constructed shelters of wood, supported by mammoth tusks, covered with skins.
- Tools of include fine points, sharp knives and scrapers.
- Flake tools → ppl living in colder climates to make clothes
- Scraping tools → preparing animal hides
- Axes with wooden handles
- Some stone points were hafted onto spears.
158
tool manufacture: homo neanderthalensis
- Edges of flakes shaped and reworked (sharpened)
after use
- Pressure flaking
- Flint became a preferred material to produce stone tools because of the very predictable way in which it would chip when struck with another hard object (much finer workmanship was possible).
- The Levallois tool making method involved preparing a core and striking off a large oval flake which was then retouched on one surface only.
159
selection pressures: homo sapiens
- Natural selection favoured increased
intelligence as a means to overcome challenges in the environment (can live anywhere!)
- A strategy to minimise the effect of selection pressures by developing appropriate technology and behaviour patterns
160
culture: homo sapiens
- Very fine tool technology requiring lots of work
- First appearance of cave paintings, bone carvings and clay statues.
- Began hunting selected animals eg. mammoth.
- Animals provided source of meat, clothing, tools, material for shelters
- Musical instruments, finely crafter stone and bone tools, ivory jewellery, paintings = cultural advancements of Cro-Magnon man (artefacts)
- Greater linguistic competence → colonising range of geographical areas → move from nomadic lifestyle to village way of life
(Neolithic or Agricultural revolution)
Planting of crops
Farming and domestication of animals
- Civilisations grew out of agriculture
161
tool culture and use: homo sapiens
- Development of new stone technology characterised by specialised and standardised stone blade tools which replaced the Mousterian technology.
- Long narrow blades were the basis of most tools, adapted for special functions by careful retouching of the edges.
- Use of bone and antler as a tool making material to produce needles, harpoons etc.
**AURIGNACIAN** - Cro-magnon
Formed from prepared cores rather than crude flakes
Made from bone
**SOLUTREAN**
Blades formed in the shape of laurel or willow-leaves
**MAGDALENIAN**
Use of bone and antlers over the use of flint and stone
162
tool manufacture
- Production and use of stone
- Finer detail and smaller tools
163
trends in tool culture and its indications about hominid lifestyle
1. greater variety of materials used/use of stone only to bone, anther, ivory, wood: hominids used resources more effectively/used more variety of resources/understood how to use their environment better
2. greater number of blows/increased workmanship/time into tool production/greater complexity: hominids completed more complex jobs/did finer work/had time to create
3. tools became more specialised/tools used to make tools/hafted tools: hominids had more specialised roles within communities
164
aurignacian
Blade-like tools
Made by removing long, flat rectangles from core stone
Effective in cutting useful as a cutting tool
165
solutrean
Willow-leaf/leaf shaped tools
Made by pressure flaking
No apparent practical purpose/purely ornamental
166
magdalenian
(Mostly) tools of bone and antler
Made from a burin/from a chisel-like cutter tool
Needles/spear points/spear throwers/etc.
