Which scientist is known for noting the universality of expressions across species?

The recognition of the universality of expressions across species is fundamentally attributed to Charles Darwin. In his seminal work "The Expression of the Emotions in Man and Animals," Darwin explored how emotional expressions are not only significant in humans but also observable in many animal species. He argued that certain expressions arise from the evolutionary history shared among species, suggesting that they serve similar functions related to communication and social interaction. This perspective laid the groundwork for understanding the biological basis of emotions and their expressions beyond mere cultural or learned behaviors. The emphasis Darwin placed on evolutionary continuity among species highlights the innate nature of these expressions, making his contributions foundational in the field of animal behavior.