An ecosystem that is more than 3 billion years old

Since it is clear that microbes do not leave fossils behind, through indirect fingerprinting in some of the oldest rocks we have proven that there was life 3.7 billion years ago. But how can we differentiate between the fingerprint of one microbe and the fingerprint of another, to the point that we can say that it corresponds to a different “species”?

At the starting point, “several potential biomarkers need to be combined,” just to make sure they are biological signatures and not geological ones. Write researchers From Germany, Sweden and South Africa in the latest issue of the magazine Precambrian research. It is a mixture containing sedimentary rocks from Buck Reef, found in South Africa and studied since the 1980s: in this formation, one of the best preserved from this distant past, we find morphological and geochemical signatures of three species of bacteria.

But three types of bacteria isn't enough for us to talk about an “ecosystem,” and what this new research adds is just that An analysis of existence There are two different forms of carbon: carbon-12 or carbon-13. The number refers to the number of neutrons in the nucleus of a carbon atom.

Organisms prefer to use carbon-12, so they usually have more of this type of carbon, but the ratio can vary between species, providing biologists with information about their metabolism. According to the new study, one type of bacteria was already able at that time to use light in its life cycle, which today we call photosynthesis. Another reason may have been the release of methane, which the others were feeding on. Through this type of effect we can assume an ecosystem, that is, a whole in which different species complement each other, or even depend on each other – which is what interests biologists. Who responded to this research?Taking into account the aging of these organisms.

Incidentally, it also tends to reinforce the idea that life must have appeared very early on our planet, Probably more than 3.7 billion years agoTaking into account the time scale that was necessary to reach the “advanced” stage of these traces remaining in the rocks of South Africa.