Primitive humans used a combination of sounds and gestures to communicate in early languages. Vowel sounds were among the first sounds produced, as they require no manipulation of the throat or mouth. Consonants were also used. The basic units of sound are called phonemes, while the smallest units of meaning are morphemes. Early sentences consisted of a verb to indicate an action and a noun as the subject or actor, allowing for simple statements, questions, and commands. Over time, language became more complex with the addition of adjectives, adverbs, and dependent clauses, leading to more advanced sentence structures and forms of communication like complex oratory. The evolution of language technology allowed humans to develop literacy through writing systems.