Why do dogs have big brown eyes?

2024-10-22 10:45:00

Originally dogs had the yellow or blue eyes of wolves, but those colors did not convey safety to humans, so they intervened in the evolutionary process to the point of having large brown eyes. This is the conclusion of a study conducted by the prestigious Royal Society, which shows that dogs have the eyes that humans havewe are what they have.

If we analyze them from a physiological point of view we will verify this Externally, dogs’ eyes are quite similar to ours.since they have a retina, an iris, a pupil, a cornea and a lens. On the contrary, analyzed internally, their particular vision of the world is given by existing differences.

Dog eyes have two color receptors (cones) – we have three -, a greater number of motion sensors (rods) and the so-called “tapetum lucidum”, a layer of cells located in the retina that acts as a mirror of light Allowing dogs to perceive more clarity in the dark.

The Royal Society is interested in dogs

But in the eyes of dogs, in addition to the large iris, another detail should attract our attention. Which? That All dogs, with a few exceptions, have brown or brown eyes.

It is an evolutionary trait in which the human being has a great responsibility and in this sense a recent study by the Royal Society (Royal Society of London for the Advancement of Natural Science) has come to the conclusion that the process of domestication e The intervention of man in it is the explanation of the predominant color in the iris of dogs.

Founded in 1662, the Royal Society is the oldest scientific society in the UK and the world and its studies have a planetary reach, which is why few scientists would doubt that humans have influenced the color of dogs’ eyes.

Why the color brown?

In the early evolutionary stage, dogs and wolves were not that far apart, but as dogs became closer to humans and advanced in their domestication process, our ancestors found the eyes of the wolf to be less than reassuring.

It was to make animals less threatening like humans that we began to intervene in domestic dogs.so that, although our ancestors were unaware of Mendel and his laws of genetics, they began to favor so-called dominant genes or traits. How did they do it?

By allowing dogs with desired characteristics, such as having brown eyes, to breed with each other and vice versa, thus preventing the genes of wolves were transmitted to subsequent generations. Something that somehow continues to be maintained, given that some racial standards penalize yellow and amber colors in the eyes.

On the other hand, There is also human intervention in the size of dogs’ pupilssince older pupils – as happens with newborns – are associated with the concepts of friendship and trust.

What about blue-eyed dogs?

Up to 9-12 weeks of age, many puppies have a bluish hue in the eyes, a consequence of the lack of melanin in the iris. It is simply a temporary circumstance, which In adult dogs it occurs naturally only in some dog breeds (Alaskan malamute, Siberian husky, Weimar Braco, Border collie or Australian Shepherd).

In other cases, the blue color of the irises has to do with an alteration in pigmentation – albinism – or even with purely genetic problems linked to certain types of coat (merleextreme white, etc.).

On the other hand, Bluish discoloration of the iris can also appear as a degenerative symptom in older dogs. or as a consequence of pathologies such as canine infectious hepatitisiriocyclitis or uveitis and nuclear sclerosis.

Finally, Those dogs that have different colored eyes suffer from a natural anomaly called heterochromia. and it usually has a congenital origin which is not a cause for concern, although if this color change occurs during the animal’s life it could be glaucoma or another pathology which will require a visit to the vet.