Final answer:
The out-of-Africa theory suggests that modern humans originated in Africa and then migrated to other parts of the world. Studies of mitochondrial DNA and the Y chromosome provide evidence of a common ancestor in Africa.
Step-by-step explanation:
The out-of-Africa theory suggests that modern humans originated in Africa and then migrated to other parts of the world. Studies of mitochondrial DNA (mtDNA) and the Y chromosome support this theory by providing evidence of a common ancestor in Africa.
Mitochondrial DNA is passed down from mother to child and can be used to estimate the timeline of genetic divergence. Research indicates that all modern humans have mtDNA inherited from a common ancestor in Africa around 160,000 years ago.
Similarly, the Y chromosome is passed down from father to son. Studies show that all men today inherited a Y chromosome from a male who lived in Africa around 140,000 years ago. These findings provide molecular evidence supporting the out-of-Africa theory of human origins.