Scientists have found that a. the oldest known fossils of modern humans were discovered in morocco, in northwest africa. b. from mtdna evidence, modern humans evolved from 16 "branches," all living in africa. c. the longer mtdna remains in a closed population, the less frequently that dna mutates. d. humans from asia, australia, europe, and new guinea all migrated to africa, contributing their mitochondrial dna. e. genetic diversity decreased as early humans migrated away from africa and founded new populations.