Like most human traits, blue eyes are determined by genes, and no two people have exactly the same hue. It works a lot like ...

The eyes of a Cuban rock iguana, a gargoyle gecko, a blue-eyed ... compound eyes (brown spot, far right) to avoid predators in the water column. A female (lower left) spends most of her life ...

Lighter eyes are idealised across societies, which often posit brown eyes on the most ‘boring’ end of ... when those windows are a shade of ocean blue, looking out into cloudless skies.

It seems a little unfair. The ladies love blue eyes, and babies already have a cuteness advantage. The iris is the muscular ring around the pupil. And its color depends on a protein called melanin ...