Constant interbreeding between small adjacent local groups
Evidence in Support of the “Out of Africa” Hypothesis
1. Compared to other animal species modern humans have a very
low degree of variability in our mtDNA.
2. There appears to be a very low degree of variability in the Y
chromosome among all modern males.
3. Within modern human mtDNA, African groups appear to have the
greatest degree of variability.
• This strongly suggests that Africa was the place of origin for all
Dating our mtDNA point of Coalescence • As time passes, genetic variability steadily increases.
• Random mutation should be the only source of variability in
• The longer an individual species is in existence, the more these
mutations will accumulate in its mtDNA.
• If these mutations do occur randomly, then over long periods of
time they should occur at a relatively constant rate.
Another Line of Evidence: Changes in Material Cul