In Greenland a patch of melting snow has revealed a structure formed by mineral deposits which is dated to about 3.7 billion years ago,the discoverers reported online August 31 in Nature. The oldest known fossils before this discovery date back to 3.5 billion years .
We know a lot about our planet earth, we know that it is about 4.5 billion years old. We know in its earlier stages earth was a very different place than what it is today. It was constantly being bombarded with space debris during the early years of the formation of the solar system. This period is called the Late Heavy Bombardment which ended about 3.8 billion years ago.
The Earth Probably looked like this during the late heavy bombardment.
One of the questions that we still don’t have an answer to is when did life itself start. What has puzzled researchers around the world is the fact that we have uncovered fossils which date back to less than a 100 million years after the Late Heavy Bombardment, since at this time the earth was a very violent place and it is unlikely that life could exists in those conditions.
These rocks could be the oldest fossilized evidence of life on Earth. These 3.7-billion-year-old structures are called Stromatolites and are found in other places as well but none has been aged been back this far in time.Unlike other animal fossils, these are mineral deposits which are formed by colonies of photosynthetic bacteria. Rocks formed by living microbes have a very distinctive chemical signature with which researchers can ensure with an high level of probability that these rocks are actually crafted by single celled bacteria.
If once given the conditions life can pop into existence in such a small time then our galaxy should be swarming with life. Given the fact that it is estimated that there are more than 300 billion potentially habitable planets in our Galaxy which have been orbiting their stars for billions of years.
Or it could also mean that life existed on earth even before the Late Heavy Bombardment in closed protected niches. Although these questions till remain unanswered, with every new discovery we get closer and closer to the truth.