Genes Evo & Dev L7

Question 1

Outline the origin & dispersal of modern humans

Answer 1

•	Origin of humans:
-	300,000 yrs -> Modern humans -> Africa
-	200,000 yrs -> Travel to Greece & china -> die out 
-	70,000 yrs -> disperse worldwide 
Dispersions possibly -> climate change

Question 2

What evidence is there for the origin of modern humans and their dispersal?

Answer 2

• Oldest modern human fossils -> >200, 000 yrs -> East & North Africa.
Heterozygosity -> decr. with incr. distance -> East Africa.
Richest genetic variation -> ancestral areas

Question 3

What is heterozygosity?

Answer 3

• Heterozygosity:

Genetic variation.

Question 4

How many human genomes are there? Describe one similarity in the history of these genomes.

Answer 4

• Six human genomes

 Bottleneck -> 60-70,000 yrs -> 12,000 people -> possibly climate change.

Question 5

Describe the origin of the Neanderthals.

Answer 5

• Neanderthals -> left Africa before modern humans.
 400, 000 – 30,000 yrs
 Cousins of modern humans, not ancestors.
 Split >800,000yrs ago

Question 6

Describe the characteristics/practises of the Neanderthals.

Answer 6

 Used animal hides
Male skull -> severely worn down front teeth
-> use as third hand in prep of animal hides.
 Made jewellery
Shell & tooth necklace
 Cave art
Marks -> Gibraltar cave -> made long before arrival of modern humans in Europe.
 Buried dead
High cinc. Pollen grains in graves
>Implies laid flowers with bodies.
 Very small numbers across Europe -> disappeared.
Small groups of at most 12.

Question 7

Describe the genetic variation of Neanderthals & their relations to modern humans.

Answer 7

Sequence -> Neanderthal genome -> 2010
 Breeding -> Non-Africans & Neanderthals
&raquo_space;Neanderthals not separate species (according to biological definition)
 3% non-African DNA -> Neanderthal.
 Varied genes -> skin colour, immune response –(Contributed to skin colour variation)
 96 amino acid differences -> Neanderthals & Humans.
 3117 regulatory regions DNA
 Neanderthal variants -> genes slight incr. osteoporosis, blood-coagulation disorders & nicotine addiction.
 Study of various genes -> links -> Neanderthal DNA & depression, obesity & certain skin disorders
->Incr/decr. risk depending on variants.
 Blood-coagulation disorders -> possibly related -> Neanderthal immune genes
->Archaic genes -> possibly helped H.sapiens cope -> diseases outside Africa.
Many humans -> Neanderthal & Denisovan genes -> encode proteins -> sense pathogens & launch rapid immune response.

Question 8

Describe the Denisovans.

Answer 8

• Denisovans:
 40,000 yrs -> tooth -> Denisova cave, Siberia -> 2008
Published in 2011.
 Discovery -> finger bone.
 Modern Asian populations -> contain Denisovan genes
Tibetans -> EPAS1 allele -> Denisovans.
 At least 3 events -> interactions w/ modern humans
 Discovery -> bones-> dna sequenced -> Genome -> offspring -> Neanderthal mother & Denisovan father-> bone evidence
 Denisovan art
Marks -> bones >100,000yrs ->China -> linked to ancient hominins (not modern humans)

Question 9

Use an example to explain how genetics can be used to identify perceptions of individuals long dead.

Answer 9

• Can use genetics to identify perceptions of individuals long dead:
 Difference -> gene for OR7D4 -> certain smell -> preference depends on gene differences in nose -> perception of androstenone
Altered neuron activity
»Single letter changes -> DNA
 Neanderthal & Denisovan opinion -> androstenone
> Neanderthals -> RT -> hated smell.
> Denisovans -> Novel genetic variant (A204T)
Never seen before

Question 10

What other archaic form of humans were there and what is known about them?

Answer 10

• Asian & African populations -> interbred -> unknown archaic forms.

• Homo floresiensis -> Hobbit
No DNA yet extracted from remains
Humid, warm climate.

Question 11

What makes us human?

Answer 11

•	What makes us human?
Cooperation & societal structure. 
     >Art 
        ->Ochre factory -> South Africa
        ->Cave art -> Indoneisa

Question 12

What were the consequences of human tools?

Answer 12

•	Human tools
Building of houses/structures
Extinction of megafauna eg. Mammoths
   >Spears 
   >Gun invention

Question 13

What activities of humans contribute to increased CO2 levels?

Answer 13

•	Increased CO2 levels:
	Construction
	Meat-eating
	Transport
	Energy