Tabin and Chiasson narrowed down the collection to 279 irises from 52 species and subspecies of felids after sorting out various qualitative aspects of the images, such as a clear, shadow-free view of the animal’s eyes. Then, he applied a set of algorithms to identify and quantitatively categorize the iris color of animals into distinct groups. About 80% of the examined species and subspecies of cats had more than one eye color.
Tabin drew different colors on a tree of cat evolutionary relationships. The resulting statistics showed which cat eye colors were common among the ancestors of all living felines. This method is known as “ancestral state reconstruction”. Based on the results of the study that Archive database published, the early ancestors of cats probably had brown and gray eyes.
Tabin says that brown color in cats’ eyes is not exceptional; Because this eye color is also present in the closest relatives of the feline family, such as hyenas and civets. However, as soon as gray appeared in the ancestors of cats, there was an explosion in eye color. Gray is an intermediate color and an interruption in the production of melanin pigments that darken the iris.
This break may have given the cats the flexibility to maintain a balance of different pigments, thus making it easier to create different colors. In fact, all other iris colors found in all feline species today, including yellow, blue, hazel, and green, appeared independently in more than one lineage. Hazel and green eyes even seem to have evolved over dozens of different time periods.
Tabin speculates that certain colors were more popular with cats than others; Because cats preferred some of these colors to choose their mates. Other researchers say that these colors may have evolved randomly.
Show Jin Lu, an expert in evolutionary genetics of wild cats at Peking University, says: “The color of cats’ skin and fur often matches their eye color; Because these colors depend on the production of melanin pigments. “Thus, eye color may be a ‘side effect’ of the animal’s coat color selection.”