The Origins of Modern Humans in Africa
Over twenty-five years ago, geneticists sequenced mitochondrial DNA from a diverse sample of human populations and hypothesized that all humans have a common origin in Africa 200,000 years ago. The broad outlines of this hypothesis remain remarkably unaltered, but many details of our African origin continue to be elusive. After decades of advances in human genetics, we are no longer data limited - either in terms of DNA samples or genomic loci, but there is little consensus on many key issues. These include: where in Africa did the species originate? And what did the ancestral population look like physically? Additionally, is there a discordance between anatomically modern humans and behaviorally modern humans? Specifically, I will explore patterns of genetic diversity across Africa and models for modern human origins. In the past, I have argued for a geographic origin of Homo sapiens in southern Africa. I discuss whether genetic data is concordant with archaeological data and suggest directions for future research. In particular, phenotypic adaptation to regional environments within Africa may provide clues to the ancestral location of modern humans via tests for local adaptation to specific environmental features (e.g. ultraviolet radiation, malaria).