George Kubler was one of the most important art historians of the 20th century, who is especially relevant today mainly for shifting the emphasis from high art to what is now known as ‘visual culture’ and for being the first genuinely global art historian. But what he has been most widely known for is the rejection of the biological metaphor of art: the general idea that artistic styles and movements grow, flower and then wither away. I argue that Kubler did not in fact reject the biological metaphor of art, but rather replaced a pre-Darwinian biological metaphor with a post-Darwinian one, which bears remarkable similarities to Ernst Mayr’s concept of population thinking, developed exactly at the time when Kubler wrote The Shape of Time. Importantly, Kubler’s post-Darwinian biological metaphor seriously can help us to understand his distinctive art historical explanatory scheme.