Monolids

What it is

A monolid is an upper eyelid that lacks a visible crease or fold. This feature is frequently observed among people whose ancestors originated from the Pacific Rim region. It includes groups such as East Asians, Northeast Asian peoples, and Indigenous peoples of the Americas. The structure differs significantly from other populations where a distinct crease is typical.

History and origin

Historical records show this eyelid shape was long considered the mainstream beauty standard in East Asia. Ancient terracotta warriors from the Qin Emperor's mausoleum all display monolids. Traditional paintings, including Gu Kaizhi's Admonitions Scroll and Tang dynasty court lady portraits, consistently depict figures with this feature. Japanese ukiyo-e prints by artists like Kitagawa Utamaro also featured monolidded beauties.

What it means

In traditional East Asian aesthetics, slender-eyed monolids represented the dominant ideal of beauty for many centuries. This preference persisted through various dynasties, influencing artistic representations from ancient clay sculptures to Ming and Qing figure portraits. The style remained central to cultural depictions of elegance and femininity in regions like Japan and China.

The science

Modern genetics identifies monolids as a complex trait influenced by multiple genes rather than a simple single-gene pattern. While older models suggested autosomal recessive inheritance, genome-wide association studies link the rs1415425 locus on chromosome 14 to eyelid formation. Variants near the BMP4 and ABCC9 genes also affect crease depth. These factors explain why two monolidded parents might occasionally have a child with double eyelids due to polygenic effects.

Good reading and sources

• Monolids on WikipediaEncyclopedia
• Wikidata recordOpen data