A fresh examination of meteorites that landed in the United States, Canada and Australia is bolstering the notion that early in Earth's history, such objects may have delivered chemical ingredients vital for the advent of life.

Scientists had previously detected on these meteorites three of the five chemical components needed to form DNA, the molecule that carries genetic instructions in living organisms, and RNA, the molecule crucial for controlling the actions of genes. Researchers said on Tuesday they have now identified the final two after fine-tuning the way they analyzed the meteorites.

Unlike in previous work, the methods used this time were more sensitive and did not use strong acids or hot liquid to extract the five components, known as nucleobases, according to astrochemist Yasuhiro Oba of Hokkaido University's Institute of Low Temperature Science in Japan, lead author of the study published in the journal Nature Communications.

Nucleobases are nitrogen-containing compounds crucial in forming DNA's characteristic double-helix structure.

Confirmation of an extraterrestrial origin of a complete set of nucleobases found in DNA and RNA buttresses the theory that meteorites could have been an important source of organic compounds necessary for the emergence of Earth's first living organisms, according to astrobiologist and study co-author Danny Glavin of NASA's Goddard Space Flight Center in Maryland.

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