It should surprise no one that the body of the violin has changed very little over 400 years since the instrument was invented in 16th century Italy, as generations of violinmakers have simply copied the creations of masters such as Antonio Stradivari (1644–1737). But a new analysis, published this week in PLOS ONE, suggests that violins come in four slightly different basic shapes. Unlike other factors such as wood properties and bow pairing, the exact outline of a violin bears little influence on its acoustic quality, reflecting instead the historical period and idiosyncrasies of its maker. To study how violin contours change over time, Dan Chitwood, a plant biologist and avid viola player at the Donald Danforth Plant Science Center in St. Louis, Missouri, analyzed photographs of more than 7000 auctioned violins made between the years of 1560 and 2003. Chitwood used a statistical technique called elliptical Fourier descriptor analysis to quantify the entire outlines of the violins for comparison. He found that the violin shapes fall into four major groups, typified by the creations of Giovanni Paolo Maggini (1580–1630), Stradivari, Nicolo Amati (1596–1684), and Jacob Stainer (1617–1683), an Austrian violinmaker who created the fiddle above. Violinmakers of the same extended family tend to create similarly shaped instruments, Chitwood found. Curiously, he found no characteristic shape for the Guarneri family, which included Bartolomeo Giuseppe Guarneri del Gesu (1698–1744), the violinmaker whose reputation rivals Stradivari's. Instead the violins made by the numerous Guarneris fell into two shape categories: the Amati and the Stradivari. Chitwood says the statistical technique used in the violin analysis will also help him in future studies on how the shape of leaves evolve.