Re: What is Bacillus permians and how is it the oldest living organism?

Hi Troy,

Thanks for your question-this is interesting, isn't it? It's claimed that these Bacilli are 250 million years old. It would be extremely difficult to determine their age directly from the cells-what the scientists have done is measured the age of the rocks in which the salt crystals that contain the bacteria were found. This can be done by measuring the ratios of various radioactive elements in the rocks-we know how fast these elements break down, so we can work out how old the rocks are.

You are right to be very skeptical of these claims. Many other similar claims have been made in the past, and many have turned out to be wrong. The most difficult thing is to prove that the growing bacteria are from inside the salt crystals and are not contaminating bacteria from elsewhere. This is not at all easy and even if the scientists who did it are sure, they will have a hard time convincing other people. Then we have to be sure that the salt crystals in the rock really are the same age as the rock and did not form later.

Some scientists in this area have sequenced part of the DNA from organisms claimed to be very old, and noted that the DNA sequences are quite different from any organisms currently known to us. However, this fact isn't always so surprising, as only a few thousand named species of bacteria have been extensively sequenced. We think that this number represents only 1% of all the bacterial species on earth, many of which can't be grown in the lab. So DNA sequence that looks different from that of other bacteria isn't so surprising.

Many scientists also doubt that DNA can survive for such lengths of time, even in a preserving environment like salt or amber. This is due to the slow breakdown of DNA by exposure to reactive chemicals, radiation or cosmic rays in the environment. So enjoy this story and the associated links, but remember the phrase "extraordinary claims require extraordinary evidence" (Carl Sagan).

Neil Saunders