World's Oldest Fossils Found In Australia

Dexter Herbivore sends this quote from the Washington Post: "Scientists analyzing Australian rocks have discovered traces of bacteria that lived a record-breaking 3.49 billion years ago, a mere billion years after Earth formed. If the find withstands the scrutiny that inevitably faces claims of fossils this old, it could move scientists one step closer to understanding the first chapters of life on Earth. The discovery could also spur the search for ancient life on other planets. These traces of bacteria 'are the oldest fossils ever described. Those are our oldest ancestors,' said Nora Noffke, a biogeochemist at Old Dominion University in Norfolk who was part of the group that made the find and presented it last month at a meeting of the Geological Society of America."

Re:Not interesting

[the biologist]

It is really a mistake to think of the evolution of bacteria having ended at any point. They've been evolving just fine since they formed, as evidenced in part by your existence (not a joke, as you/we are derived from those early life forms). There is reasonable reason to believe that what we think of as bacteria (Eubacteria specifically) evolved after we (Eukaryotes) went our own way. At the time quoted, the atmosphere of our planet was significantly different than now, so the basic physiology of the 'bacteria' of the time would have been rather different than most 'bacteria' now.

Re:Not interesting

[ElectricTurtle]

I was going to say more or less the same thing. Modern bacteria have completely different metabolisms, internal and external structures and materials from early anaerobic prokaryotes. To say that bacteria stopped evolving from that state would be deliberately ignorant/obtuse (since you'd essentially have to argue that animal life doesn't exist).

Re:How Old?

[Guido von Guido II]

The article doesn't actually say and the Washington Post just links to the article abstract, but C-14 dating isn't used except for recent material because of its small half-life. There are a wide variety of methods used for older rocks (see here [wikipedia.org]). For instance, rubidium-strontium dating might be used, since rubidium-87 has a half life of 50 billion years. Rubidium-strontium can be used for isochron dating [wikipedia.org] as well, which doesn't require any assumptions about the amount of the daughter nuclide in the sample.

Having said that, I don't have any details on the methods actually used to date rocks in this particular region.