If you’ve ever seen your cat staring at paper or pawing at the curtains, or your dog gazing off into empty space, a new discovery explains that your pets do indeed see something you cannot.
A paper published in the biological research journal Proceedings of the Royal Society B reveals that dogs, cats and many other mammals can see ultraviolet light (UV), providing evidence that cats and dogs do in fact see things that are invisible to the human eye. While some readers have speculated these animals are seeing spirits and ghosts, science reveals that this ability is not supernatural in origin, but instead rooted in biology.
Biology professor Ronald Douglas of City University London and professor of neuroscience Glen Jeffery of University College London co-authored the paper, which details their study of mammalian eyes. In their findings they detected UV sensitivity in the eyes of numerous mammals, including cats, dogs, deer, rabbits and rodents.
In fact, many animals of all types, from insects to birds, fish to reptiles, have UV vision.
Here are some things to know about UV light:
- Most of natural UV light comes from the sun
- UV light is invisible to the human eye
- Many substances can absorb and then slowly emit UV light
- It is what make black-light posters and fluorescent pigmentations glow
- Melanin, a pigment in our skin, absorbs UV light and darkens due to gained energy
- Suntans are the visual result of darkened melanin, as they gradually dissipate the radiation
- The skin can only absorb so much radiation before there is tissue damage, hence sunburns and 90% of skin cancers
Like radio waves, infrared, visible light and x-rays, UV light is radiation that exists on the electromagnetic spectrum, but has a shorter wavelength than visible colors. This shorter wavelength prevents the range of UV light from passing through the thickness of the lens in the human eye.
The study found that the thinner lens in the eyes of cats and dogs allow ultraviolet light to pass through, which in turn enables them to detect a world of information indiscernible to humans.
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