Meteorites may have brought 5 genetic 'letters' of DNA to Earth
Meteorites Could Have Brought 5 Genetic "Letters" Of DNA To Earth
Where did the basic building blocks of life on Earth come from? A question that has baffled scientists for centuries, but a new study has found evidence to support old theories saying it came from meteorites.
Scientists from Hokkaido University in Japan discovered the compounds needed to form DNA and RNA in three separate meteorites that crashed to Earth in 1950, 1969 and 2000, suggesting that cosmic influences may have previously helped deliver these vital components of life to ancient Earth.
DNA is made up of four main chemical building blocks – the nucleobases (nitrogenous bases) called adenine (A), thymine (T), cytosine (C) and guanine (G). The sister molecule of DNA, RNA, also uses A, C and G, but replaces thymine (T) with uracil (U).
"The delivery of compounds to Earth by meteorites may have played a later role in the emergence of genetic functions for early life," the researchers said.
While previous studies have detected purines and uracil in meteorites, so far no cytosine and thymine have been found.
?What about the new study
In their new study, the team analyzed three space rocks - the Murchison meteorites, Murray and Tagish Lake.
The Murchison meteorite is a space rock that fell in Australia in 1969, while the Murray meteorite was found in Kentucky in 1950. The Tagish Lake meteorite fell to Earth recently, and reached British Columbia in 2000.
The team's analysis revealed that meteorites contain compounds previously discovered in space rocks , including guanine, adenine, and uracil.
However, it has also been found to contain cytosine and thymine, at concentration levels per billion.
"These compounds are present in concentrations similar to those predicted by experiments that replicate conditions that existed before
the formation of the solar system," the scientists said.
The results suggest that the chemical building blocks of DNA may have been produced in part by photochemical reactions in interstellar media. They added that they may have subsequently merged into asteroids during the formation of the solar system.
And while many prominent scientists believe that the building blocks of life on Earth came from meteorites, there are many other theories in circulation as well. A 2008 study led by the University of California, San Diego , suggested that volcanoes may have provided the first sparks of life.
?Where did life begin
In the same year, researchers from the University of Dusseldorf claimed that life may have begun in underwater hydrothermal vents.
Other popular theories include life released by lightning, or the first particles of life to meet on clay.
However, NASA research indicates that it is possible that life was brought to our planet from somewhere else in space.
"If life formed so quickly on Earth and there were so few water and carbon-based molecules on the planet's surface, how were the building blocks of life delivered to the Earth's surface so quickly," NASA said.
The answer may include comets and asteroids colliding with Earth, because these bodies contain abundant supplies of water and carbon-based molecules.
Source: Daily Mail
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