Final answer:
Variations in mtDNA among modern humans indicate that all modern humans have a common ancestor from Africa about 200,000 years ago, supporting the Out of Africa theory, but do not support the idea that there's no genetic variance with African populations in humans outside of Africa.
Step-by-step explanation:
Variation in mtDNA among modern humans suggests several key points about human evolution. One major finding is that all modern humans share mtDNA inherited from a common ancestor, often referred to as Mitochondrial Eve, who is estimated to have lived in Africa around 200,000 years ago. This points to the idea that modern humans likely descended from Africa, also supported by genetic variance studies.
Except for the statement that would not be supported by mtDNA variation, all contemporary humans did not just inherit mtDNA from Mitochondrial Eve, but also from other potential human ancestors due to interbreeding with other human species, such as Neanderthals and Denisovans. Specifically, the incorrect statement would be that all human populations outside of Africa show no genetic variance indicating a relationship with African populations.
The study of mtDNA provides a timeline for genetic divergence and supports the Out of Africa theory. The mtDNA evidence does not support the notion that all current human mtDNA came exclusively from a single population outside of Africa, as genomic data show intermixing with other hominin groups.