We're all aliens: How human life began in outer space

In fact, a growing body of evidence is now pointing to deep space as the possible source of the raw materials that formed the building blocks of life. The latest study, which focused on a class of meteorites that fell on to the Antarctic ice sheet, also suggests that life’s origins may have been extraterrestrial.

An analysis of the meteorites has revealed that these rocks can be induced, under high pressures and temperatures, to emit nitrogen-containing ammonia, a vital ingredient for the first self-replicating molecules that eventually led to DNA, the molecule at the heart of all life…

“What is important is the finding of abundant ammonia. Nitrogen is an indispensable ingredient for the formation of the biopolymers, such as DNA, RNA and proteins, on which life depends, and any theory that tries to explain life’s origin has to account for a supply of ‘usable’ nitrogen,” Professor Pizzarello said. “Therefore, its direct delivery as ammonia and in relatively large amounts from the nearby asteroids could have found a ‘prebiotic venue’ on the early Earth.”

Tests have also shown that the nitrogen in the ammonia released by the meteorite is composed of unusual isotopes, indicating an extraterrestial origin rather than contamination from a terrestrial source.