How Life on Earth Began: Tiny Water Droplets Could Have Created Crucial Building Block of Life

We tend to think of life as being about carbon and oxygen—but that's missing a crucial workhorse of our bodies and every other living thing: phosphorus. The element is a key ingredient of DNA, its partner RNA, and the molecule that stores energy. That means without phosphorus, not only could cells not reproduce, they couldn't even survive long enough to have a fair shot at it.

And a paper published in the journal Proceedings of the National Academy of Sciences suggests a new place where phosphorus-based molecules could have formed: on the surface of tiny droplets of water.

Of course, phosphorus is only one piece of the puzzle when it comes to deciphering the origins of life—and scientists may never have an ironclad understanding of what precisely happened more than 3 billion years ago. "I have no idea how life started on Earth; I don't know," lead author Richard Zare, a chemist at Stanford University, told Newsweek. "I wasn't there; nobody else was there either."

But what Zare and his colleagues can do without a time machine is experiment. Specifically, they've been exploring ways of creating a range of phosphorous-based compounds. They knew that people hadn't had much luck creating phosphorus compounds in vats of water, so they decided to try their luck with small droplets instead. "Water, which we think of as so benign and prevalent, can in the form of tiny droplets be very reactive," Zare said. "On the surface of droplets, there's lots of action."

10_26_water_droplet_phosphates Water droplets aren't so gentle after all. Gerard Julien/AFP/Getty Images

And it turns out that if you put sugars and a phosphorus compound called phosphoric acid into a water droplet, they stick together to form a sugar phosphate without any additional heat, energy, or catalyst. "These are all the building blocks for making RNA," Zare said. "I just think this is a very tantalizing finding." In addition to the sugar phosphates, the team has also been able to produce uridine, one of the four "letters" of the RNA code.

"I'm getting all types of excited hate mail from creationists," Zare said. He and his colleagues are continuing their experiments, trying to find ways of building up larger and larger molecules to try to make the four different bases that make up RNA, which many—although not all—origins of life scientists believe would have been the first component, since it can both reproduce itself and build proteins.

He's not sure yet what precisely those experiments will involve, but they're starting with mixing more ingredients into the droplets and exploring ways to pool and recycle the droplets. As Zare said, "I don't know; I'm going to find out."

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