Perceptual grouping explains constellations across cultures

Cultures around the world organise stars into constellations, or asterisms, and these groupings are often considered to be arbitrary and culture-specific. Yet there are striking similarities in asterisms across cultures and groupings such as Orion, the Big Dipper, the Pleiades and the Southern Cross are widely recognized across many different cultures. It has been informally suggested that these shared patterns are explained by common perceptual principles, such as the Gestalt laws of grouping, but there have been no systematic attempts to catalog asterisms that recur across cultures or to explain the perceptual basis of these groupings. Here we compile data from 27 cultures around the world to show that a simple computational model of perceptual grouping accounts for many of the recurring cross-cultural asterisms. As expected, asterisms such as Orion and the Big Dipper are common in our data, but we also find that lesser-known asterisms such as Delphinus and the head of Aries are both repeated across cultures and captured by our model. Our results suggest that basic perceptual principles account for more of the structure of asterisms across cultures than previously acknowledged and highlight ways in which specific cultures depart from this shared baseline.