Sometimes science is bizarrely interesting. For example:

Deep inside the human brain, a small gland in the middle of the forehead helps keep time. As darkness arrives, the pineal gland helps set the body’s nightly rhythm. But some creatures use the pineal gland as a sort of “third eye”, helping them detect light and shadow, though the organ doesn’t form pictures. Our human lineage lost this ancestral ability millions of years ago.

But a new evolutionary hypothesis suggests that this unassuming organ is the surviving central remnant of the eye from which our two image-forming eyes ultimately arose.

In a review published in Current Biology, researchers from Lund University and the University of Sussex argue that the lineage leading to vertebrates passed through a cyclops-like stage roughly 560 million years ago. The animal was not a one-eyed giant, but probably a tiny, wormlike marine filter feeder with a light-sensitive organ on top of its head. As its descendants returned to active swimming, parts of that central organ expanded sideways and were repurposed into paired retinas.

From my somewhat morbid dissecting experiences in high school, I always found it fascinating that an animal like a frog has basically the same organs I have, and even a worm has many of them. But animal eyes might be the most fascinating of all. I’ve spent plenty of time staring into animals’ eyes – my pet fish for example (is he awake or asleep? hard to tell), the squirrels and birds in front of my house. All these animals are looking me right back in the eyes. The connection between our eyes and insect eyes is even weirder to think about. I’ve looked into crocodile and snake eyes too, at the zoo with a nice thick piece of glass between them and me. I suppose I’ve looked into alligator eyes without that glass, from a safe distance. I’m not sure what the minimum safe distance is to keep from an alligator, and this is not a safe experiment to run. But I would say an alligator 30 feet or so away is not going to bother chasing you down on land, and if it does try you can run faster than it and it will tire quickly. If you are staring an alligator in the face in the water, that is probably the last thing you are going to see.