Interactive chart of hominin species ranges through time, placed by cranial capacity or by arm to leg length ratio, with a movable time cursor that lights every species alive at that moment

Four hominin species were alive at the same time

Human evolution is usually drawn as a row of figures walking left to right, each one replacing the last. The fossil record disagrees: species overlapped for hundreds of thousands of years, and the first trait to change was not the brain. At 3.5 million years ago the chart shows a walker with a chimpanzee-sized brain; move it to 0.3 and count the species alive at once, then switch the plotted trend to limb structure and watch when arms shorten.