What did jean piaget study in college?

Jean Piaget didn't study a specific major in the way we understand college majors today. He began his academic career very young, focusing on zoology and then shifting towards philosophy and the psychology of knowledge. He earned a doctorate in natural sciences at the age of 21, his dissertation being on mollusks. Therefore, while his doctorate was in natural sciences, his interests quickly transitioned to fields that would ultimately shape his life's work in developmental psychology.