dispersal theory evidence

what fossil evidence is there of the OOA hypothesis?

The oldest dating homo sapien fossils have been found in Africa, Homo Sapien fossils found elsewhere e.g Europe are dated to be more recent specimens, suggesting Homo Sapiens evolved in Africa and later migrated across the world.

what fossil evidence is there of the Multiregional hypothesis?

Intermediate fossils between homo erectus and homo sapien have been found in Asia, for example the Peking man fossils show both human and erectus features dating back to 750,000 years ago. Suggests the evo of erectus into human outside of Africa.

what Nuclear DNA evidence is there of the OOA hypothesis?

The greatest genetic diversity is found in African populations, genetic diversity arises from mutations overtime, and so greater diversity implies the population has existed for longer

Genetic analysis shows that all people outside of Africa are descended from one African group. Whereas the humans originating from Africa, do not descend from one African group.

what mitochondrial DNA evidence is there of the OOA hypothesis?

MtDNA evidence shows that all humans originate from one common female ancestor, lived around 150,000 to 200,000 years ago, supporting the idea of a human origin in Africa

MtDNA can be used to track population divergence and migration paths, showing the dispersal of humans from Africa.

highest MtDNA diversity in African populations, implying it the oldest population. Outside Africa MtDNA is less diverse suggesting an origin from a smaller African population.

how does MtDNA evidence work?

MtDNA is only passed down matrilineally, does not recombine and changes only by mutation. If the mutation rate is known it can act as a molecular clock to estimate the time to common ancestors.

What MtDNA evidence supports the mutliregional hypothesis?

The argument for MR hypothesis is that Human and Neanderthal MtDNA differences are small, less difference between some chimps and their sub species. The hypothesis argues that Neanderthals can be seen as a sub-species or ancestor of Humans. Though the DNA differences still sufficiently classifies them as different species

how does Y chromosome DNA evidence work?

similar to MtDNA, though it can only be passed down patrilineal, not re-combined and only affected by mutation. Can act as a molecular clock. Used to identify most common male ancestor + location

What Y chromosome DNA evidence supports the OOA hypothesis?

A mutation occurred in the African Y chromosome about 44,000 years ago. If modern humans are descended from African populations, then it would be theorised that modern Y chromosomes contain the same mutations.

Scientists tested 12000 people, and all people of Asian descent contained the mutation, implying how non-African populations descended from African populations. Supports the migration out of Africa theory.

No people of Asian-descent have mutations which African's did not have also, tracing back to a common Y chromosome Adam roughly 144,000 years ago.

What Y chromosome DNA evidence supports the MR hypothesis?

Y chromosome evidence shows migration from Asia back to Africa within the last 10,000 years, supports the idea of gene flow between continents and how gene flow allowed different erectus populations to evolve into humans simultaneously.