Here Lluís Quintana-Murci, one of the scientists at the forefront of this research reveals how population genetics is transforming our understanding of who we are. Thanks to numerous discoveries, we now know how Homo sapiens spread around the world: from their exit from Africa approximately 60,000 years ago to the recent settlement of the remote lands of Polynesia within the last millennia. Population genetics has also shown that humans mixed with now-extinct species, including Neanderthals, enabling them to adapt to new environments and survive diseases. These cutting-edge genetic findings will shape our future too, offering the key to medicine tailored to individuals. But the greatest revelation of population genetics is that we are all mixed and the product of our ancestors’ long odyssey of migrations and adaptations across the globe.