As traces of the E and L components have been found in nature, the integration hypothesis asserts that these two systems existed before human language, and that it was the combination of these two pre-existing systems that rapidly led to the emergence of human language. The Integration Hypothesis posits that it was the grammatical operator, Merge, that triggered the combination of the E and L systems to create human language. In this view, language emerged rapidly and fully formed, already containing syntactical structure. This is in contrast to the Gradualist Approach, where it is thought that early forms of language did not have syntax. Instead, supporters of the Gradualist Approach believe language slowly progressed through a series of stages as a result of a simple combinatory operator that generated flat structures. Beginning with a one-word stage, then a two-word stage, then a three-word stage, etc., language is thought to have developed hierarchy in later stages.