Flashcards in Human Evolution - Dispersal Of Hominins Deck (13):
Define the multiregional hypothesis
The multiregional hypothesis suggests that Homo Erectus dispersed from Africa approximately 1.8 million years ago into asia, europe and australia and gene flow occurred through interbreeding
What evidence is shown for the multiregional hypothesis? 3 points
Evolution occurred all over the world simultaneously. Transitional fossils found in different areas of the world support this.
Genetic evidence supports the multiregional hypothesis as modern europeans share up to 3% of their DNA with homo Neaderthanesis which supports the idea that interbreeding occurred.
An analysis provides evidence that the Denisovans in Siberia interbred with homo Neanderthalensis and homo sapiens.
How do transition fossils found in different areas of the world support the multiregional hypothesis
Shows regional genetic continuity of certain morphological traits from archaic humans to modern humans. This therefore supports gene flow
How much DNA do modern europeans share with homo Neaderthanensis and how does this support the multiregional hypothesis?
Up to 3% of DNA is shared with modern europeans, which supports that gene flow occured
How do the denisovans in siberia contribute evidence to the multiregional hypothesis?
The denisovans suggest there was interbreeding between homo Neaderthanensis, homo sapiens and denisovans
Define the out of africa hypothesis
It suggests the modern humans (homo sapiens) evolved from homo erectus in africa, then migrated to the rest of the world in two different waves, replacing all other homo species
What is thought to have happened to homo erectus as they migrated out of africa?
Homo erectus became reproductively isolated. As they were subject to different selection pressures they evolved differently, in some cases evolving into homo neanderthalensis
Some of homo erectus evolved into homo sapiens, some of them stayed as homo erectus and some evolved into other species such as homo neaderthanesis.
Why did homo erectus and homo sapiens migrate out of africa?
There was a food shortage in africa which drove the species out.
What evidence is shown in africa to prove the out of africa theory?
Current africas show more genetic diversity and variation than other human populations. This suggests an older common ancestor which could allow for more mutations to occur.
What evidence can be seen from DNA?
Mitochondria DNA which is genetic information passed down the maternal lineage dosent change over time or through mutations. Because of this, scientists can trace the MtDNA back to a common ancestor approximate 200,000 years ago.
Also modern africans MtDNA has the most variations, further supporting that the african have been around longer than other locations.
What fossil evidence can support the out of african theory?
Fossils found in africa that are homo sapiens date back 196,000 years ago which suggests the earliest modern humans descended from africa
How many waves were there out of africa for the OOA hypothesis and when were they?
Two waves, the first about 130,000 years ago and the second about 50,000 years ago