A TIMELINE FOR THE PLANET click for Home Page

The first fossils

The first hint of possible life comes from the oldest real-estate so far found on the planet. These are at Isua in western Greenland. It’s a very exciting thought that life could have got going so early. And many experts regard it as perfectly plausible.

But the idea is also highly controversial, and other experts dismiss it out of hand. As analysis techniques get more refined, first one view and then the other seems to get the upper hand. We’ll probably never know for sure.

The first apparently-solid evidence comes from deposits ‘a mere’ 3½ thousand million years ago (the Apex chert in western Australia). I say ‘apparently’ because, convincing though they appear, even these findings have been disputed, and I’m not sure of the current state of play.

I’ve taken this picture from ‘Cradle of Life’ by J. William Schopf. Note the Scale bars. 10 μm is a hundredth of a millimetre.

But, if the pros are right, then bacteria had already reached their full potential, and have not developed hugely since. Indeed the experts who studied these fossils have actually identified modern species of bacteria, that each of these fossils appear to be almost identical to.

From what I’ve read, I don’t think we should be surprised if it turns out that life really did get so far ‘so early’. Life probably emerged around an underwater volcano, or other environment equally ancient. And these were certainly aplenty from at least 500 million years before.

Five hundred million years ago from now, the planet was largely populated by trilobites and other even weirder creatures. Nothing had ventured on to the land at all (except perhaps bacteria

and algae)