Linguistics is the scientific study of language. Linguists study language just like other scientists study other natural phenomena, such as photosynthesis, the solar system, DNA, or climate change. Linguistics as we know it today is a relatively new field of study, based on the ideas of American linguist Noam Chomsky's 1955 The Logical Structure of Linguistic Theory, and subsequent works. Some linguists study the grammar, or rule system, of a language, and others are more interested in the social factors, such as gender, age, ethnicity, and other variables, that influence how we use language. The linguist Charles Hockett came up with a list of design features (or characteristics) of communication systems that we can use as a starting point. Although we might be able to broadly characterize human language in terms of a series of design features, this is not the whole story, and not a complete description of our linguistic behavior.