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LEC 141 evolutionary biology > lecture 4 and 5 human evolution > Flashcards

lecture 4 and 5 human evolution Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

when was the primate ancestor “super order” of euarchonta est?

A

80 MYA

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2
Q

when did “super order” of euarchonta split into prosimians and simians

A

50 MYA

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3
Q

another name for simians

A

anthropoids

“higher primates”

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4
Q

features of prosimians

A
  • grasping fingers & toes
  • binocular vision
    most nocturnal
    mostly arboreal
    (live in trees)
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5
Q

features of simians

A

Direct ancestors of monkeys and hominoids
Originated in Africa or Asia
different adaptive radiations (over 40MYA)

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6
Q

where are new world monkeys from and example

A

south america

marmosets squirrel monkey

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7
Q

where are old world monkeys from and example

A

africa and asia

macaques, baboons

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8
Q

how do simsians differ from prosmians

A

overlapping fields of vision
opposable thumbs (not all genera)
lived in groups (social)
Mostly diurnal (active during the day)

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9
Q

what are the apes

A

group within simians

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10
Q

who are the apes

A

All are members of the superfamily Hominoidea (the Hominoids)
Two families of hominoid:

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11
Q

what are the Two families of hominoid

A

Hylobatidae (e.g., gibbons)
the ‘Lesser Apes’

Hominidae - the ‘Great Apes’
(eg orangatan, chimps, humans

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12
Q

how similar are we to chimpanzees

A

96% similarity overall

99% similarity in coding DNA

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13
Q

key new characteristics of apes

A

Larger brain relative to their body size compared to other primates

Flexible behaviour

Tail-less

Some highly social (social interactions)

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14
Q

hands

A

opposable thumb

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15
Q

feet

A

chimp and gorillas feet shaped for trees, human shaped for flat surfaces

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16
Q

human ancestsry

A 
Hominoid the ‘Apes’ superfamily
		Hominid the ‘Great Apes’ family
			Hominine gorilla, chimp & human subfamily
				Hominin human & chimp tribe
					Hominina ‘human’ subtribe
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17
Q

chimp vs hominina anatomy

skull

A

c; posteriorly attatched

h; inferiorly

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18
Q

chimp vs hominina anatomy

spine

A

c slighly curved

h s shaped

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19
Q

chimp vs hominina anatomy arms

A

c longer than legs and used for walking

h shorter not for walking

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20
Q

chimp vs hominina anatomy pelvis

A

c long and narow

h bowl shaped pelvis

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21
Q

chimp vs hominina anatomy femur

A

c angled out

h angled in

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22
Q

who is Ardipithecus ramidus

A 
A key step towards human evolution?
Dated to around 4.4 MYA
Chimp sized brain 
Broader diet than modern chimps
At least partly bipedal
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23
Q

what did all austalopithicus have

A

Round jaw

Brain size 35% of modern humans

Stocky build

Large teeth and jaws

Various ways of moving,
but can walk upright

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24
Q

how many years ago was A. afarensis

A

4.2 - 2.8 mya

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25
Q

how many years ago was A. africanus

A

2.9-2.0 MYA

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26
Q

how many years ago was P. robustus

A

2.2-0.9 mya

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27
Q

how many years ago was P. boisei

A

2.3-1.6mya

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28
Q

past desendants had skulls with

A

flat face
large brow ridge
steepness of skull changing over time

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29
Q

example of skeleton A. afarensis

A

“lucy”
found in ethiopia 3.2 mya old
human teeth
ape like head

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30
Q

Australopithecus MAY be a direct ancestor of

A

the genus Homo

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31
Q

many species overlapped in time but…

A

where were they on space

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32
Q

some characteristics of modern humans around 2.5 mya found in skeleton of H. habilis

A 
Found with many stone tools 
Short stature
Disproportionately long arms 
BUT: Larger brain than Australopithecines
50% of current human brain size, ~750cc
Shorter jaw
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33
Q

homoerectus “replaced” Homo habilis was how long ago

A

2.0mya

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34
Q

homo erectus stats

A 
About 5 feet tall
Long straight legs 
– excellent walkers
Thick skull with steep forehead
Larger brain – 1000 c.c.’s (similar to modern human)
But still prominent brow ridge
Rounded jaw
- Ability to talk?
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35
Q

social development of H. erectus

A

Used crude tools
Built fires
Social groups
Cave dwellers/wooden shelters

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36
Q

neanderthal man stats

A

Appeared 600,000 years ago in Europe & W/C Asia
12-14cm shorter than modern humans
Large skulls, heavy bony ridges over brows
Bigger brains than modern humans
Common in Europe and Asia 70,000 years ago

37
Q

neanderthals socially develpment

A

made diverse tools
Stone and wood
lived in huts and caves

took care of injured and sick

buried dead - symbolic thinking

38
Q

what was the cro-magnon man

A

“Anatomically Modern Humans” = AMH
“Early Modern Humans” = EMH
Half way between Neanderthals and modern humans?

Looked like us, but lacked complete suite of modern human behaviours

Replaced Neanderthals by 30,000 years ago, but may have evolved 200,000 years ago (overlap in time)

Sophisticated tools
Complex social organisation
Facial expressions
Language

39
Q

cro-magnon man developments

A

Usually 1 offspring
Made cave ‘paintings’
Loss of body hair

Pigmentation (trade off for lost body hair)

Lengthened thumb
- tool use

40
Q

when did they (cmm) spread across siberia and N. america

A

13,000 years ago

41
Q

newest discovered species?

A

Homo naledi 2015 south africa

42
Q

what are the two main hypotheses to explain the origin of modern humans

A
  1. (Recent) out-of-Africa (or replacement hypothesis, recent single origin hypothesis…)
  2. multiregional (model of parallel evolution)
43
Q

what is a brief outline of the out of africa hypothesis

A

anatomically modern human evolved within africa first and then left africa to colonise new continents

44
Q

how long ago in the out of africa hyp. did amh evolve and then colonise the rest of the world

A

200-100KA (thousand years)

45
Q

in the ooa hyp. what happened when the amh colonised

A

they “replaced” regional descendants of homo erectus

46
Q

if ooa hyp. is correct what would we find was true about global populations today?

A

they should be more closely related

47
Q

what is a brief explaination of the multiregional hypothesis

A

homo erectus left africa first, colonized new continents and then AMH evolved outside of africa in multiple different regions

48
Q

for multiregional hypothesis when and where is the last common ancestor?

A

africa 1.5 million years ago

49
Q

what other evidence involving H. erectus backs up multiregional?

A

H. erectus was scattered through europe asia and africa widespreadly

50
Q

what explaination is there for similarities of modern people? (multi r )

A

product of occasional interbreeding between neighbouring populations

51
Q

what hyp. does skeletal remains support?

hominina fossils 1.2 to 1.1 MYA in spain

A

multiregional

52
Q

what does molecular genetics support?

A

mitochondrial dna indicates origins of AMH in africa with a time of genetic divergence 200,000 years ago

53
Q

what is odd about the time of genetic divergence found with mtDNA?

A

it is inbetween the times hypothesized for either theory

54
Q

why is comparision of y chromosomes useful?

A

little crossing over during meiosis means diversity in y chromosome is limited to mutations and can act as a marker for examining ancestry

55
Q

what has y chromosome evidence found?

A

there is divergence from one common male african ancestor 60 KA

56
Q

evidence that neanderthals could be a ‘link’ between erectus and sapiens

A

Neanderthals ‘split’ from descendants of African Homo migrants, but then extinct ~30 KA

Neanderthals ‘co-existed’ with AMHs for at least 1000 years

mtDNA typing shows sharp differences between AMHs and Neanderthals

57
Q

what model does neanderthal evidence favour

A

out of africa

amhs replaced neanderthals

58
Q

whats the third hypothesis

A

ASSimilation model

59
Q

brief explaination of assimilation model

A

Important contribution of a recent common ancestor from Africa (~ out of Africa model)
But emphasises assimilation rather than replacement as colonised rest of world
Predicted that archaic people (e.g. Neanderthals) contributed about 10% of living people’s genome

60
Q

what recent evidence may support the assimilation model?

A

neanderthal complete DNA sequecning shows 1 - 4% similarity with europeans and asians but not africans

61
Q

what does this neanderthal dna sequencing suggest

A

EMH evolved into modern day humans but ALSO

left africa and cross bread with neanderthals and also evolved into modern day humans outside of africa

62
Q

what newer evidence contradicts the assimilation theory

A

denisovan cave girl’s little finger
not neanderthal or modern
(found in siberia)

63
Q

how old is the cave girls little finger

A

30-50KA

64
Q

what is the fourth hypothesis

A

leaky replacement

65
Q

what is the leaky replacement hypothesis

A

Neanderthals and Denisovan populations split about 200,000 years ago – share some DNA
When modern humans left Africa, interbred with Neanderthals, approx 100,000 years ago – these then evolved into modern day Asians and Europeans
A subset of this group went east, and interbred with the Denisovians – these form the basis of modern-day Melanesians
Interbreeding still limited

66
Q

evidence for leaky replacement

A

2018 – Siberian Cave – “Denny”

Neanderthal (mom) x Denisovan (dad) hybrid

67
Q

what is the fifth hypothesis

A

if neanderthals and modern humans shared a common ancestor approx 500,000 years ago then it could be a common ancestor, not interbreeding

68
Q

new discovery opposite of out of afraica

A

into africa??????? wth lol

69
Q

how much modern african dna can be traced to into africa migrations

A

25% !!!! wow

70
Q

what distinguishes us from chimps

A
  • bipedalism
  • bisexual social groups
  • large brain (complex learning)
  • language, society culture
  • food obtained though dol and shared efforts
71
Q

similarities with other primates

A

Reproductive strategies
Enhanced communication/social behaviour
Tool use

72
Q

tool use orangutans

A

use sticks to get insects out of their nests

73
Q

tool use chimps

A

use rocks to smash open food

put leaves on their feet to walk over thorns

74
Q

communication, chimps

A

social structure
not capable of speach
capable of learning sign language

75
Q

possible reasons for human language development

A 
Substitute for grooming  (was a way to communicate)
Hunting theories
Language as a way of thinking 
Motherese (noises to calm infants)
Tool making
76
Q

how did language develop theory one

A

started with manual gestures

Moved to vocal either because of a conflict with tool use OR through associations of gesture and sound

77
Q

how did language develop theory two

A

night is too dark for gestures
speach may derive from how we use our mouths to eat or swallow
changes in brain for walking changed for speech too

78
Q

evidence for neanderthal speech

A

kebara 2 is a 60 ka male neand.

modelling of hyoid bone suggests this man had the capacity for speech

79
Q

what happened at the start of the holocene

A

cultivation started of cereal grains e.g. wheat & barley

80
Q

where were the agricultural centers

A

SW Asia, C&S America, SE Asian mainland

81
Q

how long ago was livestock domesticated

A

9KA

82
Q

what were drivers of human evolution?

A

fluctuating environments

vulnerabiltity to predation

83
Q

fluctuating environments how did this drive evolution

A

changing food sources and environmental conditions, need to be smart and adaptative to survive

84
Q

vulnerable to predation how did this drive evolution

A 
had to think ways around this
fire as protection
stone tools as weapons
communication (warnings)
shelter
85
Q

what is lamarkism

A

heritability of acquired characterisitics or instruction by the environment rather than selection by it

86
Q

example of lamarkian evolution

A

ostritch callus

87
Q

what could be a heritable mechanism for lamarkian evolution

A

epigenetics (darwinian mechanism)

88
Q

evidence language has a genetic basis

A

Language and written disorders more highly correlated in monozygotic twins than dizygotic twins

89
Q

what specific gene is related to language

A

FoxP2 gene found in many species (including humans) and removal/mutation in it usually associated with impaired communication.
So some genetic basis, but not necessarily all

LEC 141 evolutionary biology (7 decks)

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