Obviously human eyes come in many colors, but it seems black/brown eyes are the overwhelming majority across the animal kingdom.
The exceptions I’m personally familiar with are dogs and cats. Some varieties of both are blue eyed, and there are plenty of orange eyed cats. I’m guessing in both cases that is probably due to human tinkering: a mutant is born, some human saw it and thought it was cute/interesting enough to favor it in breeding.
Are there other species where humans have breed for different eye colors?
What about non-domesticated animals?
What is the advantage of the different eye colors in those species? For that matter, what was the advantage of having dark eyes? Just to better block out light that isn’t coming through the pupil?
Here’s an article on the evolution of eye colour in humans which basically says ‘we really have no idea, here’s some theories’ - so if the reasons for eye colour aren’t sorted out for us, probably nobody knows the reasons for eye colour in animals either.
One theory is simple sexual attractiveness, and that’s probably worth a look. If it were true, it would probably correlate with how good the colour vision of the animal in question is. Looking at the species above - birds have great colour vision. Cats and dogs not so much, but then any eye colour variation was probably heavily influenced by us. I don’t know about frogs, but I presume they mostly have good colour vision since their skin is often all different sorts of colours, and what else would that be useful for?
Aren’t most mammalian babies born with blue eyes? I’ve always thought that blue eyes were a failure in the maturing process caused by lack of melatonin.
I do know that we blue-eyed creatures take in more light than others. We can see marginally better in the dark than our brown-eyed kin, but are also more likely to suffer retinal burns in bright snow.
So it would make more sense if blue eyes were common in dense Jungle areas, but they aren’t. They seem to be a consequence of the light skin/hair evolution that happened when humans settled in Northern climes. Despite blue eyes being a detriment in the winter, the vitamin D producing benefits of having lower melatonin levels were all-around more positive than the occasional retinal burns were negative. And I suppose night-vision gets more useful where the days are super short.
I’ve also seen a study which suggested that all blue-eyed people go back to a single human with the mutation. But I don’t see why we should assume that a mutation could happen only once.
Nice double meaning. Intentional (“I saw what you did there)?”