lecture 4 and 5 human evolution Flashcards
(89 cards)
1
Q
when was the primate ancestor “super order” of euarchonta est?
A
80 MYA
2
Q
when did “super order” of euarchonta split into prosimians and simians
A
50 MYA
3
Q
another name for simians
A
anthropoids
“higher primates”
4
Q
features of prosimians
A
- grasping fingers & toes
- binocular vision
most nocturnal
mostly arboreal
(live in trees)
5
Q
features of simians
A
Direct ancestors of monkeys and hominoids
Originated in Africa or Asia
different adaptive radiations (over 40MYA)
6
Q
where are new world monkeys from and example
A
south america
marmosets squirrel monkey
7
Q
where are old world monkeys from and example
A
africa and asia
macaques, baboons
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)
9
Q
what are the apes
A
group within simians
10
Q
who are the apes
A
All are members of the superfamily Hominoidea (the Hominoids)
Two families of hominoid:
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
12
Q
how similar are we to chimpanzees
A
96% similarity overall
99% similarity in coding DNA
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)
14
Q
hands
A
opposable thumb
15
Q
feet
A
chimp and gorillas feet shaped for trees, human shaped for flat surfaces
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
17
Q
chimp vs hominina anatomy
skull
A
c; posteriorly attatched
h; inferiorly
18
Q
chimp vs hominina anatomy
spine
A
c slighly curved
h s shaped
19
Q
chimp vs hominina anatomy arms
A
c longer than legs and used for walking
h shorter not for walking
20
Q
chimp vs hominina anatomy pelvis
A
c long and narow
h bowl shaped pelvis
21
Q
chimp vs hominina anatomy femur
A
c angled out
h angled in
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
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
24
Q
how many years ago was A. afarensis
A
4.2 - 2.8 mya
25
how many years ago was A. africanus
2.9-2.0 MYA
26
how many years ago was P. robustus
2.2-0.9 mya
27
how many years ago was P. boisei
2.3-1.6mya
28
past desendants had skulls with
flat face
large brow ridge
steepness of skull changing over time
29
example of skeleton A. afarensis
"lucy"
found in ethiopia 3.2 mya old
human teeth
ape like head
30
Australopithecus MAY be a direct ancestor of
the genus Homo
31
many species overlapped in time but...
where were they on space
32
some characteristics of modern humans around 2.5 mya found in skeleton of H. habilis
```
Found with many stone tools
Short stature
Disproportionately long arms
BUT: Larger brain than Australopithecines
50% of current human brain size, ~750cc
Shorter jaw
```
33
homoerectus "replaced" Homo habilis was how long ago
2.0mya
34
homo erectus stats
```
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?
```
35
social development of H. erectus
Used crude tools
Built fires
Social groups
Cave dwellers/wooden shelters
36
neanderthal man stats
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
neanderthals socially develpment
made diverse tools
Stone and wood
lived in huts and caves
took care of injured and sick
buried dead - symbolic thinking
38
what was the cro-magnon man
“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
cro-magnon man developments
Usually 1 offspring
Made cave ‘paintings’
Loss of body hair
Pigmentation (trade off for lost body hair)
Lengthened thumb
- tool use
40
when did they (cmm) spread across siberia and N. america
13,000 years ago
41
newest discovered species?
Homo naledi 2015 south africa
42
what are the two main hypotheses to explain the origin of modern humans
1. (Recent) out-of-Africa (or replacement hypothesis, recent single origin hypothesis…)
2. multiregional (model of parallel evolution)
43
what is a brief outline of the out of africa hypothesis
anatomically modern human evolved within africa first and then left africa to colonise new continents
44
how long ago in the out of africa hyp. did amh evolve and then colonise the rest of the world
200-100KA (thousand years)
45
in the ooa hyp. what happened when the amh colonised
they "replaced" regional descendants of homo erectus
46
if ooa hyp. is correct what would we find was true about global populations today?
they should be more closely related
47
what is a brief explaination of the multiregional hypothesis
homo erectus left africa first, colonized new continents and then AMH evolved outside of africa in multiple different regions
48
for multiregional hypothesis when and where is the last common ancestor?
africa 1.5 million years ago
49
what other evidence involving H. erectus backs up multiregional?
H. erectus was scattered through europe asia and africa widespreadly
50
what explaination is there for similarities of modern people? (multi r )
product of occasional interbreeding between neighbouring populations
51
what hyp. does skeletal remains support?
| hominina fossils 1.2 to 1.1 MYA in spain
multiregional
52
what does molecular genetics support?
mitochondrial dna indicates origins of AMH in africa with a time of genetic divergence 200,000 years ago
53
what is odd about the time of genetic divergence found with mtDNA?
it is inbetween the times hypothesized for either theory
54
why is comparision of y chromosomes useful?
little crossing over during meiosis means diversity in y chromosome is limited to mutations and can act as a marker for examining ancestry
55
what has y chromosome evidence found?
there is divergence from one common male african ancestor 60 KA
56
evidence that neanderthals could be a 'link' between erectus and sapiens
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
what model does neanderthal evidence favour
out of africa
| amhs replaced neanderthals
58
whats the third hypothesis
ASSimilation model
59
brief explaination of assimilation model
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
what recent evidence may support the assimilation model?
neanderthal complete DNA sequecning shows 1 - 4% similarity with europeans and asians but not africans
61
what does this neanderthal dna sequencing suggest
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
what newer evidence contradicts the assimilation theory
denisovan cave girl's little finger
not neanderthal or modern
(found in siberia)
63
how old is the cave girls little finger
30-50KA
64
what is the fourth hypothesis
leaky replacement
65
what is the leaky replacement hypothesis
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
evidence for leaky replacement
2018 – Siberian Cave – “Denny”
| Neanderthal (mom) x Denisovan (dad) hybrid
67
what is the fifth hypothesis
if neanderthals and modern humans shared a common ancestor approx 500,000 years ago then it could be a common ancestor, not interbreeding
68
new discovery opposite of out of afraica
into africa??????? wth lol
69
how much modern african dna can be traced to into africa migrations
25% !!!! wow
70
what distinguishes us from chimps
- bipedalism
- bisexual social groups
- large brain (complex learning)
- language, society culture
- food obtained though dol and shared efforts
71
similarities with other primates
Reproductive strategies
Enhanced communication/social behaviour
Tool use
72
tool use orangutans
use sticks to get insects out of their nests
73
tool use chimps
use rocks to smash open food
| put leaves on their feet to walk over thorns
74
communication, chimps
social structure
not capable of speach
capable of learning sign language
75
possible reasons for human language development
```
Substitute for grooming (was a way to communicate)
Hunting theories
Language as a way of thinking
Motherese (noises to calm infants)
Tool making
```
76
how did language develop theory one
started with manual gestures
| Moved to vocal either because of a conflict with tool use OR through associations of gesture and sound
77
how did language develop theory two
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
evidence for neanderthal speech
kebara 2 is a 60 ka male neand.
| modelling of hyoid bone suggests this man had the capacity for speech
79
what happened at the start of the holocene
cultivation started of cereal grains e.g. wheat & barley
80
where were the agricultural centers
SW Asia, C&S America, SE Asian mainland
81
how long ago was livestock domesticated
9KA
82
what were drivers of human evolution?
fluctuating environments
| vulnerabiltity to predation
83
fluctuating environments how did this drive evolution
changing food sources and environmental conditions, need to be smart and adaptative to survive
84
vulnerable to predation how did this drive evolution
```
had to think ways around this
fire as protection
stone tools as weapons
communication (warnings)
shelter
```
85
what is lamarkism
heritability of acquired characterisitics or instruction by the environment rather than selection by it
86
example of lamarkian evolution
ostritch callus
87
what could be a heritable mechanism for lamarkian evolution
epigenetics (darwinian mechanism)
88
evidence language has a genetic basis
Language and written disorders more highly correlated in monozygotic twins than dizygotic twins
89
what specific gene is related to language
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
