what does it mean when people say that other animals can see “more colours” than humans?
In: Biology
Humans have three types of ‘cone cells’ in their eyes that are sensitive to ‘visible’ light, from red to violet. I put ‘visible’ in quotes because we call it that due to being the range of human sensitivity, but there’s nothing inherently special about light in the range below red or above violet (infrared and ultraviolet). Some animals have eyes that are sensitive to different ranges, and can see a larger or different spectrum of light colors.
It can mean two things. Either the animal can see things in the ultraviolet spectrum that we literally cannot see, or they are able to discriminate more colors in the visible spectrum and perceive additional subjective color.
Look at this image: https://images.app.goo.gl/B9rDqmo1ohMJzRym9
“Colour” as we see it is a spectrum of frequencies of light. Humans can see colours from the 400-700 range.
Bees (just one example) can see from the 300-600 range. Meaning they can’t see the very deep reds from the 600-700 bracket, but can see colours from the 300-400 range that we humans cannot (we don’t know exactly what colour this range looks like, since we can’t see it, but all signs suggest it’s purple).
Now look at this image: https://images.app.goo.gl/MK8cQVHGAS1Rmx6T9
You’ve probably heard of most of the forms of light outside of human range on this image. X-rays are used for medical scans, infrared light is used in TV remotes, and radio waves are used to transmit radio signals (yes, radio signals are technically a type of “light” – we just can’t see them!)
Different animals can see different ranges on this chart, but most of them don’t deviate too far from human visibility levels – many animals have far *worse* colour perception than humans (our eyes are actually pretty high tier in the animal kingdom), but there are a decent number who see “more” than us.
They have eyes that are sensitive to a wider range of light above and/or below what we can see (such as infrared or ultraviolet). We don’t know what colour their brains interpret this as – it might be something we can’t conceptualise, since we only see and think in our visible spectrum.
Or… it could be a part of the same spectrum that we see that again is detected by different cells and split differently. E.g. wavelengths that we see as pale blue vs dark blue might be broken out into a wider range that could be seen as colours we can’t visualise.
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