"Gender" comes from the Latin word genus which meant "kind" or "type". In the few hundred years before the 1950s, the term 'gender' was used only in the field of grammar. In 1955, a scientist began to use the word "gender" in new ways when referring to people, in a way that was related to their 'sex' but not quite the same. The term was not applied to other animals. They continued to have different “sexes”.