Definition: Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
Input: Sentence1: Population crashes in high density populations are so devastating that extinction becomes probable. 
Sentence2: If the number of individuals of a species increases too quickly too much in a fixed area, the species can become extinct.

extinction