The findings add weight to the theory that the chemical building blocks of life were created by reactions that took place elsewhere in the universe, possibly beyond our solar system.
The evidence hinges on the molecular structure of amino acids, the repeated chemical units that make up proteins found in all living organisms. The molecules come in left- and right-handed varieties, and only left-handed varieties are found in life on Earth.
NASA scientists had previously found a disproportionate amount of the left-handed form of isovaline, an amino acid, in a meteorite sample. The latest study confirms that the previous sample was not a one-off.
"This tells us our initial discovery wasn't a fluke, that there really was something going on in the asteroids where these meteorites came from that favours the creation of left-handed amino acids," said Daniel Glavin, from NASA's Goddard Space Flight Centre in Greenbelt, Maryland.
The scientists believe that early in its history Earth was bombarded with meteorites containing left-handed amino acids, which led to the genesis of life about four billion years ago.