World's Oldest Living Microbes May Cast Light on Aging & Life on Mars

A research team has for the first time ever discovered active DNA from living bacteria that are more than half a million years old, which may lead to a better understanding of the aging of cells and might even cast light on the question of life on Mars.

The bacteria, frozen in permafrost slowly respirate and repair their DNA, according to a report in the Proceedings of the National Academy of Sciences. The process may explain how life persists over geologic time scales, the authors say.

Other scientists have discovered viable microbes that have been trapped in amber, salt or buried deep within the earth for tens to hundreds of millions of years, but how these ancient bacteria remained alive for so long under extreme conditions has remained a mystery.

The discovery was made after excavations of layers of permafrost in the north-western Canada, Siberia and Antarctica.

This is the oldest living organism ever discovered. The discovery was made by Professor Eske Willerslev of the University of Copenhagen and an international research team

All cells decompose with time. But some cells are better than others to postpone the decomposing and thus delay aging and eventually death. And there are even organisms that are capable of regenerate and repair damaged cells. These cells – their DNA – are key to the understanding of the process of how cells break down and age.

The team found a method that makes is possible to extract and isolate DNA-traces from cells that are still active. It gives a more precise picture of the past life and evolution "because we are dealing with cells that still have a metabolistic function – unlike 'dead' cells where that function has ceased," says Eske Wilerslev.

After the fieldwork and the isolation of the DNA, the researchers compared the DNA to DNA from a worldwide gene-bank in the US to identify the ancient material. Much in the same way the police compares fingerprints from a crime. The researchers were able to place the DNA more precisely and to place it in a context.

The methods and results can be used to determine if there was ever life on the way we perceive life on earth. Darwin's theory predicts that life never returns to the same genetic level. But the team's findings poses the question: "are we dealing with a circular evolution where development, so to speak, bites its own tail if and when ancient DNA are mixed with new", says Eske Willerslev.

Posted by Casey Kazan. Adapted from the Proceedings of the National Academy of Sciences.