Interestingly, some scientists are starting to think so. Fairly recently, amino acids (see the “Biochemistry” chapter) were observed in comets, prompting the idea that these molecules, which play a key role in life on Earth, may actually be extraterrestrial in origin. Subsequent research on how these amino acids might have gotten into comets in the first place uncovered that interstellar model ices were able to serve as a breeding ground for dipeptides (a chain of two amino acids). This result further supports the notion that comets from deep space may plausibly have delivered the building blocks for life on Earth today. This contrasts with a longstanding hypothesis that the Earth’s early oceans may have served as the source from which the building blocks for life first formed.