Diamonds hide a secret about the birth of life on Earth

An analysis of some ancient diamonds is challenging the theory that it took 3 billion for life to appear on Earth.

The evolution of the first complex multicellular organisms occurred 3 billion years after the creation of Earth. This is the established theory regarding the appearance of life on our planet. But an analysis of ancient diamonds is calling the hypothesis into question. Explaining the new deduction was Dr. Michael Broadley of the Centre de Recherches Pétrographiques et Géochimiques during the Goldschmidt Conference. Diamonds would create a kind of "ideal time capsules" that trapped gases and could give us clues about the conditions under which they formed.

Diamond Research and the Birth of Life on Earth

Life on our planet requires an atmosphere suitable for our survival. One strategy for assessing whether it is possible to live on other planets is precisely to look for gases compatible with living things. Useful, in this direction, is also to understand what the Earth's atmosphere was like in the era when the first forms of life evolved. One theory is that most of the gases in the atmosphere, known as volatiles, were trapped in the Earth's mantle and played a key role in the history of atmospheric evolution as they escaped from the subsurface. Dr. Briadley, however, presented evidence during the conference that the gas composition of Earth's mantle has remained unchanged for a long time.

The stirring of Earth's crust through plate tectonics has mostly destroyed older samples of artifacts with trapped gases inside, but Broadley noted that diamonds would be able to create "ideal time capsules" with trapped gases inside at the time they formed. In Wawa, on the Canadian shore of Lake Superior, the researcher found diamonds in 2.7 billion-year-old rocks. Broadley turned the stones into graphite above 2,000° C so that they would release the noble gases trapped within them.

The concentration of helium, neon and argon in these ancient diamonds was similar to Earth's present-day upper mantle, so the major emissions must have occurred before the diamonds formed and certainly before Earth was half its present age. "This was a surprising result. It means that the volatile-rich environment we see around us today is not a recent development," Broadley said.

Degassing the Earth's mantle was not the only prerequisite for the evolution of complex life forms. The release of oxygen by photosynthesizing organisms was also necessary. However, the release of gas from the mantle is believed to be an essential prerequisite that may have served to delay other events.

On the history of our evolution, there is still much research and analysis. A great deal of help in understanding how we arrived at current life forms comes from findings. For example, recently, fossils have been found in Israel that would reveal information about the evolution of Neanderthals.

Stefania Bernardini