SNP (snip) = Single Nucleotide Polymorphism: In the old days, we called these point mutations.
When did humans evolve and from where?
Looking at SNPs in the human mitochondrial genome, we can trace the evolution of our species.
from Ingman et al., 2000, Nature. Volume 408: 708-713.
All non-Africans are related to a band of about 5,000 - 10,000 Africans who migrated north about 150,000 years ago (common branch).
The people who have existed the longest are all African (depth of branches)