TASK 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.
PROBLEM: Sentence1: Lions live in social groups called prides. 
Sentence2: Chimpanzees live in social groups called communities.

SOLUTION: groups

PROBLEM: Sentence1: Human mating behavior also involves some competition. 
Sentence2: Human mating may lead to aggressive behaviors or displays of aggresion.

SOLUTION: Human

PROBLEM: Sentence1: Individual with best survival alleles survive with the largest handicap. 
Sentence2: Animals require alleles for warmth.

SOLUTION:
alleles