Compound words are a special point of interest with the Integration Hypothesis, as they are further evidence that words contain internal structure. The Integration Hypothesis, analyzes compound words differently compared to previous gradualist theories of language development. As previously mentioned, in the Gradualist Approach, compound words are thought of as part of a proto-syntax stage to the human language. In this proposal of a lexical protolanguage, compounds are developed in the second stage through a combination of single words by a rudimentary recursive "n"-ary operation that generates flat structures. However, the Integration Hypothesis challenges this belief, claiming that there is evidence to suggest that words are internally complex. In English for example, the word 'unlockable' is ambiguous because of two possible structures within. It can either mean something that is able to be unlocked (unlock-able), or it can mean something that is not lockable (un-lockable). This ambiguity points to two possible hierarchical structures within the word: it cannot have the flat structure posited by the Gradualist Approach. With this evidence, supporters of the Integration Hypothesis argue that these hierarchical structures in words are formed by Merge, where the L component and E component are combined. Thus, Merge is responsible for the formation of compound words and phrases. This discovery leads to the hypothesis that words, compounds, and all linguistic objects of the human language are derived from this integration system, and provides contradictory evidence to the theory of an existence of a protolanguage.