This chapter explores how language helps human beings to group, distinguish, and differentiate between things in the world around them. In other words, what is the basis of conceptual thought, and how does this relate to language capacity as a whole? On the one hand, behaviourists have argued that human beings start life as a ‘blank slate’, and our language capacity is something that we learn by exposure to the language of others. On the other, Noam Chomsky proposed that humans are born with an innate capacity for language, as shown by the ease with which children rapidly learn a wide vocabulary, but also by their remarkable capacity for linking words together in complex grammatical structures. The chapter then looks at developments in the search for a biological basis for human language. Studies suggest that language in humans involves a complex interplay between a number of different genes, FOXP2 being a key one, which affect the connections between neurons in specific parts of the brain. However, it still remains unclear whether FOXP2 gene affects neurons involved in language processing per se or those that control muscles involved in speech.