Human Evolution

Question 1

What are the two theories about the origin of modern humans?

Answer 1

• They all arose in one place - Africa and then migrated to the rest of the world
• Pre-modern humans migrated from Africa to become modern humans in other parts of the world

Question 2

What is the multiregional continuity model?

Answer 2

Contends that after Homo erectus left Africa 2 MYA and dispersed into other portions of the Old World, regional populations slowly evolved into modern humans. The model contains the following components:

• Some level of gene flow between geographically separated populations prevented speciation, after the dispersal
• All living humans derive from the species Homo erectus that left Africa nearly 2 MYA
• Natural selection in region populations, ever since their original dispersal, is responsible for the regional variants (sometimes called races) we see today
• The emergence of Homo sapiens was not restricted to any one area, but was a phenomenon that occurred throughout the entire geographic range where humans lived

Question 3

What is the Out of Africa Model?

Answer 3

Asserts that modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus. Critical to this model are the following tenets:

• After Homo erectus migrated out of Africa, the different populations became reproductively isolated, evolving independently, and in some cases, like Neanderthals, into separate species
• Homo sapiens arose in one place, probably Africa (geographically this includes the middle east)
• Homo sapiens ultimately migrated out of Africa and replaced all other human populations, without interbreeding
• Modern human variation is a relatively recent phenomenon