An international genomics study has revealed that early Asians undertook humanity's longest known prehistoric migration. These early humans, who roamed the earth over 100,000 years ago, are believed to have traveled more than 20,000 kilometers on foot from North Asia to the southernmost tip of South America. Scientists have mapped the unexpectedly vast genetic diversity of Asians, who make up more than half of the world's population. These findings overturn long-held assumptions of European genetic dominance and show that native South Americans are of Asian descent. The study also sheds light on how such a vast migration and differing environments have shaped human evolution, including how populations have adapted to diseases and how their immune systems have evolved.