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Forensic Genetics > Population Genetics > Flashcards

Population Genetics Flashcards

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Biology 101 flashcards
1
Q

When did the hominid separate from apes?

A

7 million years ago - separated from apes

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2
Q

Why are our chromosomes different to those of apes?

A

There are inversions, translations and as humans we have many more function genes

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3
Q

How many chromosomes do chimpanzees have?

A

48 (we have 46)

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4
Q

Why have apes declined even more?

A

Hunting and disease (Ebola)

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5
Q

When did the bipedal hominids become apparent?

A

6 million years ago - had small canines

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6
Q

What are the main differences between hominins and apes?

A
  • We have a greater dependence on adults during childhood
  • We also have a longer life after menopause
  • Humans have reduced diversity in some parts of the genome (part of X chromosome and mtDNA)
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7
Q

Where have examples of early hominins been found?

A

Chad, Kenya, Ethiopia

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8
Q

What was present in 4 million BCE?

A

Australopithecus

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9
Q

What were the four different hominid lineages that co-existed around 2 -1 million BCE?

A

Australopithecus
Homo Neanderthalensi
Homo floresiensis
Homo habilis

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10
Q

What type of ancestor was Lucy the fossil skeleton?

A

Australopithecus - unclear whether Lucy is a direct ancestor to the homo species

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11
Q

What were the characteristics of homo florensiensis?

A

Tiny Hobbit like

Found on an isolate island in Indonesia

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12
Q

What was the sequential developmental route for homo habilis into homo sapiens?

A

Ergaster (Turkana boy) - erectus (Java and Peking man) - heidelbergenesis - sapiens (Knowing man)

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13
Q

Where have other homo erectus remains been found?

A

Around the Black Sea and in the Kalahari desert

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14
Q

When did the appearance of the Neanderthal man happen?

A

500,000 - 8000 BCE

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15
Q

When were homo sapiens seen in East Africa?

A

170,000 BCE

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16
Q

When were homo sapiens seen in Mediterranean?

A

125,000 BCE

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17
Q

When were homosapiens seen out of Africa?

A

85,000 BCE

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18
Q

What is it believed died out and were replaced by homo sapiens?

A

Homo erectus

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19
Q

What is the difference between erectus and sapiens?

A
  • Larger brains (not as large as neanderthals)
  • Greater cerebral cortex and testes
  • Dependent childhood
  • Faster weaning
  • Better at endurance running
  • Loss of hair to thermoregulate
  • Can impose the thumb
  • Shoulder girdle anatomy
  • Use fire and cook
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20
Q

When was the mesolithic era and why is this important?

A

12000 - 8000 BC
There was a Sumatra volcano that erupted for 6 years in 71,000 BCE and this lead to the last glacial period - only around 1000-10000 breeding pairs survived and a genetic bottleneck is proposed to of happened

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21
Q

What happened in 8000 BCE?

A

Neolithic farming

  • Metal tools
  • Wheel
  • Domestication of animals
  • Social groups and sheltering
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22
Q

When was the Bronze age?

A

3000 BCE

  • Copper and bronze working
  • Weaving
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23
Q

When was the iron age?

A

800 BCE

- Iron and Steel

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24
Q

When was ancient Egypt?

A

800 BCE up until 500 AD

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25
Q

What do palaeontologists study and how far back an they go?

A

Fossils

7 MYA

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26
Q

What do palaeclimatologists study and how far back an they go?

A

Isotopes and gases

1 MYA

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27
Q

What do geologists study and how far back an they go?

A

Rocks

4000 MYA

28
Q

What do genetics study and how far back an they go?

A

Ancient DNA - very limited and based towards females due to mitochondrial DNA
Also look at living DNA

29
Q

What do historical experts study and how far back an they go?

A

Written tests and oral history

5000 Y

30
Q

What do linguists study and how far back an they go?

A

3000 Y

31
Q

What do archaeologists study and how far back an they go?

A

Tools, ornaments, pottery - 2.5MYA

32
Q

When did the first movement out of Africa happen?

A

Around 1.9 MYA

33
Q

In the first move out of Africa what ancestors moved?

A

Probably heidelbergenesis and erectus

34
Q

What were the two main routes taken 1.9 MYA?

A

Up the Nile Valley

Across the red sea

35
Q

When did the ancestors arrive in SE Asia?

A

About 1.7 MYA

36
Q

When did the ancestors arrive in Europe?

A

About 1.2 MYA

37
Q

What did the first migration out of Africa cause?

A

Probably the origin of Neanderthal man - the nearest human relative

38
Q

Describe neanderthal origin

A
  • mtDNA is very different to that of humans (202 substitutions opposed to 20 between hominins)
  • No mtDNA contribution to modern humans
  • Low diversity compared to modern humans/apes
39
Q

Why were doubts raised about neanderthals and humans being very different species that did not interbreed?

A
  • mtDNA differences are associated with known artefacts
  • The Neanderthal characteristic genes could have been lost in genetic drifts in last 30000 years (as they were a relatively small group)
  • Research based on small fragments of recent fossils from only a few sites
  • Evidence of difference does not reach statistical significance in pair-wise analysis with humans
40
Q

What is the overall consensus around neanderthals and humans?

A

They were distinct species (neanderthals arrived in Eurasia first) that co-existed for around 5000 years before neanderthals died out

41
Q

Could Neanderthals of interbreed with Homosapiens?

A
  • 1-4% of DNA from non-africans appears to have an ancient neanderthal ancestry
  • Very crude analysis as there is a common ancestor between neanderthal and humans
  • There is anatomical evidence of skeletons with neanderthal and human features
  • mtDNA can’t show interbreeding mediated through males
  • Whole genome analysis shows more similarity to Europeans than Africans
42
Q

What examples are there of mixed ancestry/interbeeding from only studying the mtDNA?

A
  • Out of Asia expansion only identified through Y analysis

- Lemba people of SA - Y analysis shows interbreeding of Jews and Bantu that was not revealed by mtDNA

43
Q

What is the mutliregional theory of human evolution?

A

After Homo erectus left Africa and dispersed into other portions of the Old World, regional populations slowly evolved into modern humans
- In africa: homo dragster through heidelbergenesis into sapiens
- Out of africa: homo heidelbergenesis/erestus evolved to neanderthalensis and then into sapiens
Evidence favouring heidelbergenesis exists as they has larger brains and were better with tools

44
Q

What is the out of Africa model?

A

Asserts that modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus

45
Q

What support is there for the out of africa model?

A
  • Multiregional model of HE to HS would have required a large gene flow
  • Human anatomical features were discovered in Africa 130 KYA and 50 KYA in the rest of the world
  • Genetic diversity was higher in Africa - longer evolution/larger populations
  • mtDNA and Y phylogenies have root in Africa - mtDNA 160 KYA and Y chromosome 140 - 500 KYA
46
Q

When was the second movement out of Africa?

A

600 KYA

47
Q

Who moved out of Africa 600 KYA?

A

Ergaster - thinner skull bones, reduced supraorbital sulcus (eye cavity)

  • Acheulean tools - these tools have symmetry to them and some intelligence must have gone into there development
  • Associated with he appearance of G6PD deficiency in Europe - offers protection against malaria
48
Q

What happened within Africa 200KYA?

A

Bantu expansion from the Cameroon - replaced most of the African populations in next 2000 years

49
Q

When was the third out of africa movement?

A

Around 100 KYA

50
Q

What is this third migration believed to potentially be?

A

A founder effect migration as only mtDNA L3 haplotype (a set of genetic determinants located on a single chromosome) found outside of africa
- Some interbreeding could of taken place

51
Q

What has mtDNA and y chromosomes shown about the TMRCA?

A

230 KYA - mtDNA
100 KYA - Y
This isn’t when humans developed - X and autosomal loci suggests much older origins of population - 1MYA tailing out to 4 MYA

52
Q

What are the revised models of evolution?

A

Single origin model
High migration model
Low migration model

53
Q

What is the basis of the single origin model?

A

Few migrate out of Africa so they are less diverse but then out of Africa and in Africa expand (no gene flow)

  • Consistent with african frequency data
  • Consistent with mt and Y data
  • Not consistent with autosomal data and earlier estimate of tMRCA
54
Q

What is the data supporting/not supporting the high migration model?

A

High gene flow - archaic populations contribute equally
Consistent with observation of recent and ancient TMRCA
Not consistent with many loci containing rare polymorphisms

55
Q

What is the data supporting/not supporting the low migration model?

A

Low gene flow - recognises Africa source but allows for admixture
Consistent with observation of recent and ancient TMRCA
Consistent with many loci having high probability of single archaic origin - especially for haploid that have small effective population number

56
Q

Why is mitochondrial eve unlikely?

A

Only if diversity within a population comes from a single time and place which is unlikely as there are influences from the outside

57
Q

Where do our ancestors come from?

A

Go back 30 generations there are greater than a billion potential ancestors
Go back 40 generations - there are a thousand billion

58
Q

What were the invasions carried out by the Barbarians in the 4th century?

A 
Hunnic invasion 
Visogoth 
Vandal invasion 
Frankish invasion 
Anglo Saxon invasion
59
Q

When was the Islamic empire formed?

A

6th century

  • Arab invasion from medina
  • Persian empire, Syria and Egypt
60
Q

When were the vikings present?

A

8th Century

  • Scandinavian sailors
  • Across Atlantic ocean to Greenland
61
Q

When was the Mongol invasion?

A

12th century - lead by Genghis Khan

62
Q

When was America discovered?

A

14th Century

63
Q

When was the slave trade?

A

15th to 19th century - western europeans into western africa - ships to north and south america

64
Q

When was New England founded?

A

15th century

  • Spanish and Portugese to the south
  • French, British and Dutch to the North (Virginia to Canada)
65
Q

What and when was penal transportation?

A

15th Century - people who had commits crimes were shipped of to different parts of the world

66
Q

When was the industrial revolution?

A

19th Century - great migration of America (rural south to north)

Forensic Genetics (1 decks)

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