How Life Began: Missing Link Chemical in First Living Cell Discovered

A team of scientists working to replicate the conditions of early Earth in modern lab experiments may have cracked one of the key problems in understanding how life began. They think they've found a compound that plausibly could have been present and could have handled phosphorylation, a step required to produce several building blocks of life.

They explain their work in a paper published today in the journal Nature Chemistry. Those experiments deal with a compound called diamidophosphate, nicknamed DAP, which the scientists think could have been floating around on an early Earth. And if it was, their experiments suggest it could have been the catalyst for creating several crucial ingredients.

"It reminds me of the Fairy Godmother in Cinderella, who waves a wand and 'poof,' 'poof,' 'poof,' everything simple is transformed into something more complex and interesting," senior author Ramanarayanan Krishnamurthy, a chemist at the Scripps Research Institute in California, said in a press release.

A tap from DAP's magic wand may not turn a pumpkin into a carriage, but what it does do is attach a small chemical building block called a phosphate onto the compound it meets—a process called phosphorylation. Phosphorylation, and the reverse process that removes a phosphate group, is an incredibly common process in life that underwrites chemicals ranging from neurotransmitters to proteins.

So the team behind the new study tested DAP's ability to form a few phosphorylated compounds that scientists think were crucial to life's beginning: nucleosides like those that make up RNA, the cousin of DNA that could have passed information between generations of early life; fatty acids, like those that make up the membranes of every single one of your cells; and amino acids, which form the building blocks of proteins that execute most of the tasks required by life.

In all three categories, the team found that DAP, plus a second compound they think also could have been present before life began, plus a little water, could tap its wand and phosphorylate the predecessor compound to create the target compound.

Unfortunately, modern lab experiments will never let scientists determine conclusively what happened all those years ago—to be absolutely positive how life began, they would need to travel back in time and watch the whole process unfold. But experiments can at least tell us what is and isn't feasible—the next best thing.