The Sentinelese people on the Andaman Islands are one of the only groups of people who cannot see blue...
They are the most isolated tribe left and did not require cognition of the colour blue, so they did not evolve into being able to see blue.
They are, however, some of the happiest, healthiest people alive!
PS: If you want to write a poem with me, just message me here on commaful. I'd love to collaborate!