The answer is enzymes. Enzymes are biological catalysts, which means they decrease the amount of activation energy needed to start a reaction, therefore speeding up the rate of the reaction. They are part of the protein macromolecule group. Without them, our bodies would not process things efficiently or fast enough for us to live.
If they didn't adapt, they couldn't survive in the changed environment. Because abiotic factors determine the kind of organisms that are able to live in certain conditions.
