A 2009 study suggested that blue eyes were present in Siberia during the Bronze Age; 15 of 25 Andronovo culture specimens (60%) from the Krasnoyarsk area had blue (or green) eyes.

Blue eyes are rare in mammals; one example is the quite recently-discovered Blue-eyed Spotted Cuscus (Spilocuscus wilsoni). The trait is hitherto known only from a single primate other than humans – Sclater’s Lemur (Eulemur flavifrons) of Madagascar. While some cats and dogs have blue eyes, this is usually due to another mutation which is associated with deafness. But in cats alone, there are three known mutations which produce blue eyes – the one found in Siamese cats does not have adverse health effects, while the others