“It means that two of the essential components of life, a protocell’s membrane and its proteins, provided the conditions for each other to exist. By sticking to the fatty acids, the amino acids gave them stability. In turn, the fatty acids concentrated the amino acids, perhaps encouraging them to coalesce into proteins. From the very beginning, these partners were locked in a two-step dance that continued for 3.5 billion years, and helped create all the richness of biology from a starting place of mere chemistry. “I agree completely,” Keller tells me. “It’s completely magical. You need those two parts together.””