Human DNA came to Earth from outer space, Japanese scientists say

(ORDO NEWS) — Researchers have found in meteorites the chemical ingredients needed to start life on Earth.

A team of researchers from the Institute of Low Temperature Sciences (ILTS) at the University of Hokkaido (Japan) reported the discovery of nucleobases in three carbonaceous meteorites.

Nucleobases are nitrogen-containing compounds critical to the formation of the characteristic structure of the DNA double helix.

The study, published in the journal Nature Communications, says that the researchers studied the material of three meteorites – one that fell in 1950 near the city of Murray in the US state of Kentucky, another that fell in 1969 near the city of Murchison in the Australian state of Victoria, and a third that fell in 2000 near Lake Tagish in the Canadian province of British Columbia.

All three are classified as carbonaceous chondrites, made from rocky material thought to have formed during the birth of the solar system.

They are rich in carbon: the Murchison and Murray meteorites contain about 2% organic carbon by weight, and the Tagish Lake meteorite contains about 4% organic carbon. It is known that carbon is the main component of organisms on Earth.

The confirmation of the extraterrestrial origin of the complete set of nucleic bases found in DNA and RNA supports the theory that meteorites could be an important source of organic compounds necessary for the emergence of the first living organisms on Earth.

Scientists around the world are trying to understand what was behind the emergence of life on Earth. They believe that various chemical compounds came together in a warm watery environment, where a living microbe formed, capable of reproducing itself.

Two nucleobases, called cytosine and thymine, recently identified in meteorites may have been overlooked in previous studies because they have a finer structure than the other three, the researchers said.

Five nucleobases would not be the only chemical compounds needed for life. Among other things, they needed:

  • Amino acids, which are components of proteins and enzymes
  • Sugars that are part of DNA and RNA
  • And fatty acids, which are structural components of cell membranes

“This study demonstrates that meteorite nucleotide diversity could serve as the building blocks of DNA and RNA on the early Earth,” the paper says.

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