Essential amino acids Humans and the majority of animal species cannot synthesize essential amino acids (Info: Campbell biology 9th edition). However, meat, eggs, et cetera provide all required essential amino acids. And meat comes from animals. 1.Main question: So how do these animals we eat get their essential amino acids if they cannot synthesize them either? 2.My hypothesis: I know they can get it from their diet, but wouldn't it become a never-ending cycle of passing on essential amino acids? 3.Subquestion if hypothesis is proven: If that is the case, where did these essential amino acids come from? Thanks in advance! Kind regards, Jay

Bacteria and plants are able to synthesize all amino acids, as they are capable of nitrogen fixation. If animals eat plants, they get the essential amino acids needed for their proteins. Humans get the essential amino acids by eating these animals or directly by consuming plants. So yes, it is a never-ending cycle of passing.