instruction:
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.
question:
Sentence1: Humans have collected and grown mushrooms for food for thousands of years. 
Sentence2: humans have collected and grown porcinis for thousands of years.
answer:
Humans


question:
Sentence1: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Phototropism means growing toward the energy of light.
answer:
phototropism


question:
Sentence1: Faster metabolism means more calories consumed, and usually, weight loss. 
Sentence2: mammals generate heat by consuming calories.
answer:

calories