The answer likely lies in the primordial soup, a mineral-rich mixture that was lapping against the shorelines on early Earth, but there’s still a big question mark hovering over just how these molecules managed to link up to form life-giving proteins.
To find out, researchers at Georgia Tech have recreated some of the conditions common to a pre-life Earth, and discovered that drying and rewetting this primordial soup lets these key peptides form quickly and relatively easily.
Amino acids are often called the building blocks of life: these organic compounds link up in chains to form peptides, polypeptides and eventually, proteins.
Amino acids themselves are fairly common and have even been found in space, but those all-important links can be fragile, and it’s not known just how they formed chains long enough and stable enough for life to arise.
Since they’re very similar to amino acids, hydroxy acids can act as stand-ins to form peptide chains with amino acids through what are called ester bonds.
Next, the researchers mimicked the gentle catalyst they believe might have kicked life into gear: the regular cycles of drying out and rewetting of the primordial soup as it lapped against rocks, dried out in the sun and was washed back into the soup by rain.
The stand-in hydroxy acids played a crucial part in the process: while they form chains more easily, they also break apart more easily, but by the time they break, they’ve already formed a framework to allow the hardier amino acid bonds to form longer peptides.