Scientists re-create what may be life's first spark

Researchers have re-created a split-second impact of a meteor with primordial Earth, and shown how the 3.5-megaton collision might have reorganized common molecules into some of the early building blocks that led to all life.

The researchers zapped clay and a chemical soup with the laser to simulate the energy of a speeding asteroid smashing into the planet. They ended up creating what can be considered crucial pieces of the building blocks of life.

The feigned cataclysm took place in a lab in Prague using a 492-foot laser system to create a high-density plasma, with temperatures soaring to about 7,640 degrees Fahrenheit, and see its effects on a pool of formamide.

That chemical has been identified in the tail of comets and around young stars, and some researchers believe it could have been present on the early Earth nearly 4 billion years ago.

In the experiment, the formamide broke down and recombined, forming precursors to the four basic building blocks of RNA and DNA, the cornerstones of life, according to the study published online in the journal Proceedings of the National Academy of Sciences.

"These findings suggest that the emergence of terrestrial life is not the result of an accident but a direct consequence of the conditions on the primordial Earth and its surroundings," the researchers concluded.

The laser-zapping produced all four chemical bases needed to make RNA, a simpler relative of DNA, the blueprint of life. From these bases, there are many still-mysterious steps that must happen for life to emerge. But this is a potential starting point in that process.

Scientists have been able to make these RNA bases other ways, using chemical mixes and pressure, but this is the first experiment to test the theory that the energy from a space crash could trigger the crucial chemical reaction, Civis said.

The impact mimics those that likely occurred during the early formation of the solar system, when the planets as we know them came together through massive collisions of debris surrounding the sun. A common model of this "late heavy bombardment" period suggests early Earth was hit with a billion tons of material per year, each typically speeding through its thin atmosphere at more than 2,000 miles per hour, regularly creating impact craters several hundred feet in diameter.

It would have been both a disastrous and fortuitous time for early "biological" molecules, which could be annihilated and reformed many times over, according to researchers.

Since the earliest laboratory experiments, more than 60 years ago, showed that electrical energy could transform simple organic molecules into amino acids, researchers have been finding novel and sophisticated ways to simulate or model the so-called spark of life.

They have focused on mimicking the energy provided by lightning, hydrothermal energy, ultraviolet radiation, nuclear decay, and collision with an astronomical object, such as an asteroid or comet.

Steve Benner, a biological chemist at the Foundation for Applied Molecular Evolution in Florida, said the experiment is quite relevant because it produced the starting material that would have been around in an early Earth.

But John Sutherland of the MRC Laboratory of Molecular Biology in Cambridge, England, said the amount produced of one base was so small that the results don't seem relevant. Others also downplayed the work.

"There is no known geochemically feasible process for the generation of pure formamide in a plausible primitive Earth environment," said Jeffrey Bada, a chemist at the University of California, San Diego/Scripps Institution of Oceanography.

At best, he said, formamide is an inert, transient byproduct of a simpler reaction. Although the study's chemistry is "interesting from a straight chemical synthesis point of view," Bada said, "the relevance of this to the prebiotic chemistry of the early Earth is questionable."

Civis and his co-authors maintain that formamide could have persisted on early Earth, or been carried by a comet. Regardless, Civis believes their experiment would work with other molecules. "Maybe you can do additional experiments, for example, with formaldehyde," he said. "Formaldehyde was the first molecule found in space."

"It looks like it is possible," he said.