Humans share a surprisingly strange ancestor with all other vertebrates. New research suggests that far back in evolutionary history, one of our earliest relatives had a single eye, much like a tiny cyclops, positioned on top of its head. Scientists from Lund University and the University of Sussex report that all vertebrates can be traced back to this ancient, one-eyed organism. According to their findings, the remains of that original "median eye" still exist today, but in a very different form. It has become the pineal gland, a small structure deep in the brain. "The results are a surprise. They turn our understanding of the evolution of the eye and the brain upside down," says Dan-E Nilsson, professor emeritus in sensory biology at Lund University. A Worm-Like Creature From 600 Million Years Ago This distant ancestor lived nearly 600 million years ago. It was a small, worm-like animal that spent most of its time in one place, feeding by filtering plankton from seawater.…