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Human Evolution Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How are primates “advanced”?

A

more developed features & certain behaviours;

reduced teeth & olfaction

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2
Q

How are primates “primitive”?

A

evolved early in mammalian evolution;

retain features that most other mammals have lost

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3
Q

What features have primates retained that most other mammals have lost?

A

5 digits, clavicle

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4
Q

How do we know what primate features are shared, derived, or primitive?

A

compare to features in a primitive mammal (oppossum)

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5
Q

What are the two large divisions of primates?

A

prosimians & anthropoids

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6
Q

What type of primate are lemurs?

A

prosimians

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7
Q

Which species is the most primitive of the primates?

A

lemurs (prosimians)

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8
Q

What are the characteristics of lemurs/PROSIMIANS?

A

small cranium,
long snout,
long tail

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9
Q

What are the 2 smaller groupings within the anthropoids, from largest/most general to smallest/most specific?

A

hominoids, homonids

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10
Q

What are some characteristics of new world monkeys?

A

noistrils far apart,
prehensile tail (can grasph/hold things),
strictly arboreal,
eat fruits or insects

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11
Q

What are some characteristics of old world monkeys?

A 
nostrils close together,
though seat pad,
quadripedal,
mostly arboreal/some terrestrial,
marked sexual dimorphism
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12
Q

What is sexual dimorphism?

A

phenotypic difference between males and females of the same species

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13
Q

What does arboreal mean?

A

living in trees

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14
Q

What are the unique characteristics of apes?

A

larger,

no tail

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15
Q

What type of ape is a gibbon and what are some of its characteristics?

A

lesser apes;

vocal, brachiate, monogamous

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16
Q

What does brachiate mean?

A

arm swinging - a form of locomotion to swing from tree to tree

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17
Q

What are some species of greater apes?

A

orangutans,
gorillas,
chimpanzees

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18
Q

What species are more closely related to us than to other primates?

A

chimps & bonobos

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19
Q

What are some characteristics of orangutans?

A

herbivores

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20
Q

What are some characteristics of gorillas?

A

herbivores,

strong sexual dimorphism

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21
Q

What are some characteristics of chimpanzees?

A

adaptable,
use tools,
can kill animals for food

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22
Q

Where do nearly all primate species live?

A

tropical places

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23
Q

Why are many primate species endangered?

A

habitat destruction,
hunted for food,
hunted & sold (bush meat),
killed because they eat crops

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24
Q

What body parts of primates have shared derived features?

A

hands & feet, mammary glands,

eyes, nose, teeth, brain (cerebral cortex)

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25
Q

What are some shared derived features of the hands & feet of primates?

A 
adapted for grasping,
manipulating digits,
opposable thumb (pollex),
tactile pads with ridges on palms/soles,
flattened nails instead of claws
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26
Q

What is a pollex?

A

opposable thumb

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27
Q

What is a shared derived feature of the mammary glands of primates?

A

reduced to 2

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28
Q

What are some shared derived features of the eyes of primates and what do they give them?

A

sophisticated vision;
eye socket surrounded by bone,
binocular - forward facing, close-set eyes,
enlarged visual centres in brain

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29
Q

What are some shared derived features of the noses of primates?

A

shortened snout,

reduced olfactory abilities

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30
Q

What are some shared derived features of the teeth of primates?

A

simple cusp design of incisors & premolars,

reduced in number & size

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31
Q

What are some shared derived features of the brains (cerebral cortex) of primates?

A

enlarged in relation to body size,

unique fissures

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32
Q

What does binocular vision entail?

A

forward-facing, close-set eyes

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33
Q

What are the 3 hypotheses of the selective pressures that favoured the evolution of the shared derived features of primates?

A

arboreal theory,
visual predation theory,
angiosperm radiation theory

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34
Q

According to the arboreal theory, what selective pressure favoured the evolution of the shared derived features of primates?

A

life in trees

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35
Q

Are the 3 hypotheses of selective pressures that favoured the evolution of the shared derived features of primates mutually exclusive?

A

no

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36
Q

Which theory is the “classic view” of the evolution of the shared derived features of primates?

A

arboreal theory

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37
Q

What is the problem with the arboreal theory?

A

not all arboreal animals have the traits (the shared derived features of primates)

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38
Q

According to the visual predation theory, what selective pressure favoured the evolution of the shared derived features of primates?

A

improved prey-catching ability

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39
Q

According to the angiosperm radiation theory, what selective pressure favoured the evolution of the shared derived features of primates?

A

new feeding niches appeared with flowering plants (fruits & flowers)

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40
Q

Was the first primate like anything alive today and, if so, why might that be?

A 
perhaps a tree shrew;
convergent evolution (since tree shrews aren't primates)
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41
Q

In what might a tree shrew resemble the ancestor of primates?

A

appearance & ecology (insectivorous, arboreal)

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42
Q

Why must convergent evolution be used to explain why tree shrews might resemble the first primate?

A

tree shrews are NOT primates;

they LACK the shared derived features of primates

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43
Q

What are some extinct anthropoids, and where did they live?

A

Eosimias (Asia),

Aegyptopithecus, Dendropithecus, Proconsul (Africa)

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44
Q

What are some trends seen in anthropoids going from oldest to most recent?

A

larger body size,

more open, drier habitat (more terrestrial)

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45
Q

What selective pressures may have favoured larger body size in Anthropoid evolution?

A

cooling climate,
competition for food,
redator defence,
competition for mates

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46
Q

Why might the cooling climate have favoured larger body size in Anthropoid evolution?

A

larger size = lower surface to volume ratio,

so larger animals lose less heat

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47
Q

Why might competition for food have favoured larger body size in Anthropoid evolution?

A

larger animals can displace smaller ones (especially in groups)

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48
Q

Why might predator defence have favoured larger body size in Anthropoid evolution?

A

larger animals can fight back (especially when in groups)

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49
Q

Why might compeition for mates have favoured larger body size in Anthropoid evolution?

A

males compete for access to females (inrasexual selection);

evidence is seen in sexual dimorphism (body size ratio 5:4 to 2:1 (male:female))

50
Q

When did the last common ancestor of monkeys and apes live?

A

~ 25 mya

51
Q

When did the last common ancestors of humans and apes live, and what is this date based on?

A

~ 6-8 mya;

based on DNA

52
Q

Why are dates of ancestral species very approximate?

A

based on DNA;

get revised with new evidence

53
Q

What is the initial defining physical feature that distinguishes a homonid?

A

bipedalism

54
Q

What are some possible advantages of bipedalism?

A

hands free to carry food & young, make/use tools,
less skin exposed to mid-day sun,
more efficient locomotion in open areas,
better view of surroundings

55
Q

What are some anatomical changes associated with the change from quadripedal to bipedal locomotion?

A

pelvis changed shape/tilted forward to support erect position
femur shifted to support weight out to the side,
grasping foot became walking foot
(?)

56
Q

What changes in the skull have occured with bipedalism?

A

foramen magnum facing downwards,
shortening of jaw & reduction of teeth,
development of chin

57
Q

What is the foramen magnum?

A

“big hole” - where spinal cord enters brain

58
Q

What homonid characteristics followed bipedalism?

A 
decrease in sexual dimorphism,
decrease in tooth size,
reduction of face, nostrils point down, less olfaction,
increase in brain size,
ability to make sophisticated tools,
development of language & culture
59
Q

What finding showed evidence of upright posture and how?

A

the “Toumai” skull (Sahelanthropus tchadensis);

human-like features: walked upright, small canine teeth, short middle part of face, foramen magnum facing downwards

60
Q

Where was the “Toumai” skull found and when did it live?

A

found in Chad, Central Africa;

lived 6-7 mya

61
Q

What ape-like features did the “Toumai” skull exhibit?

A

small brain, sloping face, very prominent brow ridges, elongated skull

62
Q

What lifestyle did “Ardi” (Ardipithecus ramidus) have and what does it suggest

A

lived in woods (not savanna), climbed & walked;

suggests a human-ape common ancestor that was not chimp-like

63
Q

When did the Ardipithecus ramidus live?

A

4.4 mya

64
Q

What species is the likely ancestor of Homo, when did it live, and what human-like characteristic did it have?

A

Australopithecus afarensis;
3.85-2.95 mya;
walked upright

65
Q

What is one of the 3 known “robust” australopithecines?

A

Paranthropus boisei

66
Q

When did the Paranthropus boisei live, and how does that relate with our ancestors?

A

lived 2.3-1.2 mya;

contemporary with our ancestors

67
Q

Which species was an evolutionary dead-end and what does that mean?

A

Paranthropus boisei;

no descendants left

68
Q

How does the structure of Paranthropus boisei relate to its diet?

A

eats tough leaves;

sagittal crest, massive jaw, high-crowned teeth (horse/cow-like)

69
Q

What were sympatric in east Africa for a long time (and what was that time span)?

A

several species of homonids;

from ~1-3 mya

70
Q

What diet is though to be important in human evolution and why?

A

meat:
hunted or scavenged,
more quickly digested,
non-toxic (unlike many plant items),
concentrated food source (calories, protein, fat, nutrients),
accomodation of larger brains (cooked food = reduced dentition = room for them)

71
Q

What may have allowed reduction in dentition, and what would that have accomodated in humans?

A

the habit of cooking food;

accomodation of larger brains

72
Q

Which species was known as the “handy man” and why?

A 
Homo habilis (2.4-1.4 mya);
earliest known hominid to make and use tools
73
Q

What species was the earliest known homonid to make and use tools?

A

Homo habilis

74
Q

What species was the earliest known user of fire, and where did it remain?

A 
Homo ergaster (1.7 mya);
stayed in Africa
75
Q

What species was ancestral to both Homo erectus and Homo sapiences?

A

Homo ergaster

76
Q

Which homonid lost sexual dimorphism, and what does that mean?

A

Homo ergaster;

males and females same size

77
Q

What was unique about Homo erectus?

A

physically better adapted for more efficient bipedal movement;
first homonid to leave Africa

78
Q

When did Homo habilis live?

A

2.4-1.4 mya

79
Q

When did Homo ergaster live?

A

1.7 mya

80
Q

When did Homo erectus live?

A

1.89 mya to 143000 ya

81
Q

When did the first homonid first leave Africa, and which species was this?

A

Homo erectus;

1.8 mya

82
Q

What species was known as “the Hobbit” and why?

A 
Homo floresiensis (95000-17000 ya);
only 1 m tall
83
Q

What were the characteristics of Homo floresiensis?

A 
walked fully upright;
only 1 m tall;
enlarged frontal lobes (but brain only 1/3 size of ours);
no chin;
made and used tools
84
Q

Where were Homo erectus fossils found?

A

in Africa and across Africa

85
Q

Where were Homo floresiensis fossils found?

A

Flores Island, Indonesia

86
Q

When did Homo floresiensis live?

A

95 000 - 17 000 ya

87
Q

What was the likely ancestor of Homo floresiensis?

A

Homo erectus

88
Q

When did Homo heidelbergensis live?

A

700 000 - 200 000 ya (but may reach back to 1.3 mya)

89
Q

Where did Homo heidelbergensis live?

A

Africa, Europe, possibly China

90
Q

What species may be the last common ancestor of Homo sapiens and Homo neanderthalensis?

A

Homo heidelbergensis

91
Q

What does DNA evidence suggest regarding Homo sapiens and Homo neanderthalensis?

A

that the 2 lineages diverged from a common ancestor sometime between 350 000 and 400 000 years ago;
Euorpean branch lead to H. neandethalensis and African brance lead to H. sapiens

92
Q

When did Homo neanderthalensis live?

A

200 000 - 28 000 years ago

93
Q

Which species inhabited Europe during the ice age?

A

Homo neanderthalensis

94
Q

What were the characteristics of Homo neanderthalensis?

A

physically robust,
well-adapted to conditions,
accomplished hunters,
took care of elderly

95
Q

What 2 Homo species overlapped and may have interbred?

A

H. sapiens and H. neanderthalensis

96
Q

What were the Denisovans and what does DNA evidence suggest regarding their interaction with other Homo species?

A

members of a lineage closely related to Neandertals;

Neanderthals & Denisovans interbred with H. sapiens

97
Q

Where and when did Homo sapiens evolve?

A

in Africa;

200 000 ya

98
Q

What behaviours were performed by Homo sapiens?

A

culture, sophisticated tools,

hunting, art, care of injured, sick

99
Q

What are the characteristics of “anatomically modern humans”?

A

slight sexual dimorphism,
globular, voluminous cranium (short, high, domed),
bony elements above eye (brow ridge) are reduced,
flatter face, tucked under cranium,
vertical forehead,
mental iminence (pronounced chin),
gracile skeleton (long slender bones)

100
Q

What does maternal inheritance mean?

A

males do not pass it on in sperm

101
Q

Why is mtDNA helpful compared to nuclear genes?

A

evolves quickly;

in nuclear genes, mutations accumulate more slowly & recombination mixes up genes, obscuring history

102
Q

How does mtDNA differ from nuclear DNA?

A

single circular chromosome,
only 37 genes,
most of the nucleotides are non-coding

103
Q

Who was Eve (according to the Eve hypothesis)?

A

woman to whose mitochondria all living humans can be traced back
(i.e. the 1st female Homo sapiens)

104
Q

What does genetic divergence data suggest regarding Eve?

A

that she lived ~ 200 000 years ago

105
Q

Which human populations are the most divergent, how do we know this, and what does this tell us?

A

sub-Saharan African populations;
highest mtDNA variability;
therefore the oldest

106
Q

What is the FOXP2 gene associated with?

A

speech

107
Q

When did a mutation in the FOXP2 gene occur?

A

near split of homonid-great apes

108
Q

When did the frameshift mutation in genes for chewing muscles occur?

A

~ 2.4 mya

109
Q

What may have allowed expansion of the brain’s cortex?

A

deletions in non-coding regions

110
Q

What do many homonid fossils appear to represent?

A

evolutionary “dead-ends”

111
Q

What are the characteristics of the Homonid evolutionary tree?

A

no evidence of “steady progress”;

no direct path to modern humans

112
Q

What advanced behaviours are exhibited by primates?

A

high level of parental care,
high level of sociality,
cultural evolution

113
Q

What are the characteristics of primates in relation to their high level of parental care?

A

few young, born helpless;
long gestation period, grow slowly;
long dependent period;
relatives often help

114
Q

What are the characteristics of primates in relation to their high level of sociality?

A

most species live in groups,
complex social relationships,
dominance hierarchy,
learn from others, not just family

115
Q

IDENTIFY THE PRIMITIVE AND THE SHARED, DERIVED FEATURES OF PRIMATES AND OF HOMONIDS

A

(learning outcome)

116
Q

CLASSIFY PRIMATES AND PLACE THEM ON A PHYLOGENETIC TREE

A

(learning outcome)

117
Q

IDENTIFY SPECIES OR GROUPS OF SPECIES OF NON-HUMAN PRIMATES AND ALSO HOMONIDS FROM A DESCRIPTION OF THEIR CHARACTERISTICS

A

(learning outcome)

118
Q

DESCRIBE TRENDS IN THE EVOLUTION OF ANTHROPOID PRIMATES AND HOMONIDS, AND INIDCATE WHAT SELECTIVE PRESSURES MAY HAVE FAVOURED THE OBSERVED CHANGES

A

(learning outcome)

119
Q

PLACE THE SPECIES OF HOMONIDS, AND THEIR NOVEL CHARACTERISTICS, IN RELATIVE CHRONOLOGICAL ORDER

A

(learning outcome)

120
Q

INDICATE WHICH HOMINIDS WERE LIKELY DEAD ENDS AND WHICH MAY BE ANCESTRAL TO US

A

(learning outcome)

121
Q

EXPLAIN WAHT MOLECULAR EVIDENCE HAS REVEALED ABOUT OUR EVOLUTION

A

(learning outcome)

DISP Biology (12 decks)

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