Why did Galen make errors about human anatomy?

Galen’s anatomical errors primarily stemmed from the prevailing social taboos of his time, which prohibited the dissection of human corpses.12

Because he could not perform human dissections, Galen relied on the dissection and study of lower animals, such as Barbary apes, pigs, sheep, and goats, to form his understanding of anatomy. He then made inferences about human structure based on these animal models. Consequently, his descriptions—such as his anatomy of the uterus—often reflected the physiology of the animals he studied rather than that of humans.1

While Galen was a meticulous observer and a skilled researcher who made significant contributions to medical knowledge, these limitations meant that his anatomical work contained fundamental inaccuracies. It was not until the 16th century that physicians like Andreas Vesalius demonstrated that Galen’s anatomical descriptions were frequently based on animal rather than human structures, leading to the eventual correction of these long-standing errors.12