Migration and Hybridization

Question 1

What is multiregional evolution? What is Out of Africa theory? Are they in contrast or do they support the same opinion? What do genetic data tell us about it?

Answer 1

Multiregional evolution: evolution occurred at several places from local, older hominins.

Out of Africa: humans evolved all from Africa.

This debate was ended by genetic studies, in which mitochondrial DNA was isolated from placentas of women from different ethnic groups (coalescence modelling):

• 166-249 Kya
• higher differentiation between africans than within europeans/asians
• H. sapiens replaced old hominins without mixing

After genetic studies where made on fossils, the Out of Africa theory was adjusted in “Adjusted out of Africa theory” since:

• human genome is 99% similar
• genetic signatures of our ancestors can be seen in our genome
• H. sapiens cause extinction of archaic species

Question 2

What are the migration pattern of H. sapiens?

Answer 2

1. From Africa to Arabian peninsula; from there to both Europe and Asia/Russia and Australia; from there to America

Question 3

What are the theory on Neanderthal extinction?

Answer 3

Extinction theories:

• compentition
• climate change
• infectious disease transmission
• population size
• isolation

It is believed that Neadertharls weren’t actually extinct as soon as H. sapiens arrived, but that there was assimilation and mixing:

Question 4

What are the local adaptation in Neaderthals?

Answer 4

1. well-adapted to colder climates (strong arms and hands)
2. similar/larger brain volume than H. sapiens. Different brain anatomy
3. stone tools and fire
4. culture and traditions

Question 5

Give an overview on hybridization among archaic human. How does it affect medical phenotypes in modern humans?

Answer 5

Neaderthal genes:

1. TLR1: innate immunity
2. SLC15A4: autoimmune disease
3. STAT2: communication immune system

Denisovan allele:
1. EPAS1: increase viscosity of the blood