I was web surfing on one of my days off (Wed) & stumbled on this blurb (from Glencoe, MN):
Samantha Johnson, seventh grade, purple ribbon and state science fair trip for her project “Can Cats See Color?” She also won the Thin Film Technology Corp. independent research award of $50.
I have always been fascinated by evolutionary biology, so I immediately sought out the item, only to be disappointed by finding only this same blurb.
So I started doing some online research and found some interesting information from the Natural History Museum of Los Angeles County, which said that while cats can see some colors, they don’t distinguish colors as well as humans, since this capability is not crucial to their surivival. What intrigued me was the assertion that
It is not possible to see well in the dark and have excellent color vision.
This intirgued me and gave me pause to try to think this through. My mwent back to high school biology and the fact that the huma retina is covered by rods and cones.
A quick web search reminded me that rods are specialized for vision at low light levels while cones are capable of color vision. This led me to the following theory:
- Cat’s eyes are similar to human eyes (and so also contain rods and cones).
- There is limited real estate on the retina and evolution will select for those characteristics that most benefit the animal.
- Excellent night vision is more important to a predator of small animals than color vision.
Therefore, evolution selected for excellent night vision on the cat, at the expense of color vision. Furthermore, cats must have a higher porportion of rods to cones than humans.
A little more research confirmed this when I found the following excerpt
A cat has more rods and fewer cones than humans do and this is why they can see in the dark so well.
on a site about cats.
I love this kind of investigation into evolutionary biology, especially when it involves cats.
Of course, there is a lot more to discuss regarding cats’ eyes, such as the tapetum lucidem, which explains why cats’ eyes glow so evilly in the dark. But we’ll leave that for another post.