Fossil underside and imprint in black slate Photo: El Albani et al.
Reading Complex creatures existed 2.1 billion years ago, about 200 million years earlier than previously thought. The French researchers from newly discovered fossils from the West African Gabon, which contain structures up to twelve inches long. These appear to be the remnants of highly organized organisms that lived in a time when the earth, according to current knowledge, was populated exclusively by single-celled organisms. Overall, the researchers discovered more than 250 fossils in black slates from the southeast of Gabon, which could be dated with a relatively high accuracy to the age of 2.1 billion years. The samples show a great variety of forms: some are elongated, many are bent, some even nearly round, and most of the fossils also have finger-like structures. They are of astonishing size and, unlike many other early finds, they are already visible to the naked eye.

At first glance, the fossils resemble star-shaped minerals, the so-called pyrite suns, which are also often found in such black schists. In contrast to their very symmetrical growth, however, the structures are irregular. The researchers therefore assume that the fossils are encased in stone multi-cellular organisms. This thesis is also supported by the discovery of organic hydrocarbon molecules, so-called sterols, because these are considered clear evidence of the presence of cells with cell nucleus and cell membrane.

Scientists rate this finding as surprising - so far, evidence of multicellular life older than 1.6 billion years is extremely rare. After the "Great Oxidation Event" 2.4 billion years ago, when the oxygen content of the Earth's atmosphere first increased significantly, the composition of the gas envelope was still a mix of toxic greenhouse gases. Only gradually did the conditions become more life-friendly and the then existing microbial world underwent the most significant climate change in the history of the earth: Oxygen emissions and simultaneous consumption of carbon dioxide slowly turned the atmosphere towards its current state.

The scientists do not believe that the finds are simple microbial communities, such as those found in extensive algae mats. Rather, several cells seem to have formed true colonies, whose organizational structures differ significantly from those of other unicellular communities. In order to be able to form such complex structures, signals emitted by the individual cells and ordered reactions are necessary, that is to say a kind of communication, say the scientists. If these assumptions are confirmed, the findings would be the oldest evidence of already well-developed life. So far it had been assumed that Mehrzeller originated 200 million years later at the earliest. display

Abderrazak El Albani (Université de Poitiers) et al .: Nature, online pre-publication, DOI: 10.1038 / nature09166 ddp / science.de? David Köndgen

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