Even Charles Darwin was puzzled by the evolution of the vertebrate eye. New research suggests that it traces back to a cyclopean invertebrate with a single eye atop the head. By Carl Zimmer Look at ...

Hold a pencil upright in front of your face. Close one eye, look at the pencil, then open that eye, and close the other. Did you notice that your view of the pencil shifted slightly when you looked ...

After losing its original eyes, one of our distant ancestors may have done what evolution does best: tinkered with what was available, reshaping a single central visual organ into two new eyes. That’s ...

Most animals– including us– get by with just two eyes. Two eyes are usually enough to see, move around, find food, and stay safe. But some animals in nature have taken a different path. They’ve ...