Throughout a person’s life, their body traces a continuous path over the surface of Earth. By considering only their east-west motion we can graph this path in 2 dimensions, assigning the vertical dimension to time. If the lifeline of every human who’s lived in the last 100 ka were combined into one map it must look something like this. At the top, the first humans expand throughout Africa, and then gradually east, reaching China by 60 ka BP. (The simultaneous expansion into Europe is unfortunately masked by the overlapping African longitudes.) Between 15 ka and 10 ka BP humans probably crossed a temporary landbridge into the Western Hemisphere and quickly reached the eastern tip of Brazil.