The eyes are not technically ‘smaller’, but hooded with thicker upper eyelid fat and epicanthal folds. They developed over time to protect the eyes from harsh winds and the cold. The Japanese and Koreans tend to have the ‘smallest’ eyes in the Far East, whilst bigger eyes are more common amongst native Taiwanese (not the Han Chinese descended), Filipinos, Malay and Thai. Though, as someone else mentioned, you WILL find Europeans with similar eye structure in certain areas – people of Slavic descent generally have smaller-looking eyes, as do people of Germanic descent. My father is white British, of German descent and has a lot of upper eyelid fat – my mother is almost 100% East Asian (Amis Taiwanese) and has much bigger, rounder eyes than my dad. The epicanthal fold (the curve that folds over the inner corners of the average Asian eye – it is present in around 97% of East Asians) is not exclusive to Asians though – plenty of people of other races can also have them, though it is less p