The Origin of Life on Earth - Mystery Revealed: All People Are Aliens

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.

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. 

The scientists believe that meteorites falling to Earth about 4 billion years ago could have produced a constant and replenishable supply of ammonia, and hence nitrogen, which was so necessary for the formation of the first self-replicating molecules.