Why Are Most Mammals Colour-Blind?
Most mammals see fewer colours than we do because they have only two types of colour-sensitive cone cells, while humans have three. Scientists think this goes back to the age of dinosaurs, when early mammals became mostly nocturnal and colour vision gave them little advantage in the dark.
What do dogs and cats see?
Dogs have two types of cones and can tell blues from yellows, but they struggle to tell red from green, so a red ball on green grass may be hard to spot by colour alone. Cats are also dichromats, with a palette centred mainly on blues and yellowish hues. Humans, apes and Old World monkeys regained a third cone type after a gene duplication, which may have helped them spot ripe fruit among green leaves.
Key facts
- Rods help us see in dim light; cones give colour vision in brighter light.
- Blue and humpback whales appear to lack functional cones altogether.
Where can I read the full story?
This is a short version of “A Different View” from OYLA 12+, Vol. 12, Issue 10 (October 2026). The full FAQ in OYLA 12+ compares the colour ranges of humans, dogs and whales.
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