The “bouba–kiki” effect is the perceptual correspondence between the nonce word “bouba” with a rounded and “kiki” with a spiky shape. This phenomenon – popularized by Ramachandran and Hubbard (2001), themselves inspired by Köhler’s classic work (1929) – has since been replicated numerous times in various experiments, serving as a test bed for understanding the psychology of crossmodal correspondence between sound and vision. In this talk, I will present the results of an extensive web-based study with 917 speakers of 25 different languages exploring the “bouba–kiki” effect across the globe. Controlling for genealogy and orthography, we demonstrate that the effect holds robustly across most of the investigated languages. We argue that such widespread relations between auditory signals and visual shapes might arguably have bootstrapped the origins and evolution of spoken languages by helping our ancestors form connections between speech sounds and their referents (Cuskley & Kirby, 2013; Ramachandran & Hubbard, 2001).