Climate change and human civilisation – Out of Africa Flashcards
What is the official name for the human species?
Homo sapiens.
`What causes evolution?
Random mutations of genes of individuals and natural selection.
What does natural selection refer to?
The species with the best genes suited for their environment are more likely to survive, reproduce and pass on their genes.
What is the Savanna/aridity hypotheses?
The idea that gradual drying of eastern Arica (where humans originated from) over the last few million years caused evolution of people to walk on two legs in order to walk longer distances to find food and water rather than climb trees.
How did humans adapt to environmental instability?
They became more flexible and skilled which allowed us to survive in a range of environments.
What triggered a rapid increase in human brain size?
Increased environmental instability. Much of our evolution occurred when we lived in rift valleys, where lakes frequently flooded and desertification often occurred, during a varying climate. Increasing brain sizes helped humans adapt to different environments.
What did rapid homo sapiens brain size increases coincide with in terms of the earth’s orbit?
Eccentricity and precession were causing rapid and high magnitude hydroclimate fluctuations in eastern Africa.
Where does archaeological evidence suggest Homo sapiens evolved?
Within eastern Africa – they then gradually moved elsewhere.
Why might the idea Homo Sapiens evolved in Eastern Africa be incorrect?
Because Homo Sapien remains were found in a dry rift valley (which is a good preserver of remains) where it is tectonically active (which exposes more remains to find), and people continued to search for remains here after the first ones were found. There may have been remains elsewhere which are lost or harder to find.
When is it believed non-Africans left eastern Africans?
Around 55-65Ka / thousand years ago
