The amino acids needed to generate life on Earth may have been planted when an icy comet collided 3.8 billion years ago, according to a study by British researchers. Those amino acids could have been created in the heat of the collision. Researchers have been able to generate such amino acids in experiments meant to recreate the impact. "This is the first step towards life. The next step is to work out how to go from an amino acid to even more complex molecules such as proteins," said study co-author Mark Price from the University of Kent.