Evidence of early life found in world’s oldest rubies

Researchers have found evidence of early life in rubies dating back around 2.5 billion years – an evidence that suggests presence of life some 1.5 billion years after the Earth is believed to have been formed.

The study by researchers at the University of Waterloo found a ruby sample that contained graphite, a mineral made of pure carbon It was the analysis of this carbon that led to discovery of remnants of early life.

The research team, led by Chris Yakymchuk, professor of Earth and Environmental Sciences at Waterloo, set out to study the geology of rubies to better understand the conditions necessary for ruby formation. They carried out the study in Greenland, which contains the oldest known deposits of rubies in the world.

Scientist explain that the sample they analysed is particularly unique as it for the first time they have obtained direct evidence of life dating back as much as 2.5 billion years. The presence of graphite also gives us more clues to determine how rubies formed at this location, something that is impossible to do directly based on a ruby’s colour and chemical composition.

The presence of the graphite allowed the researchers to analyze a property called isotopic composition of the carbon atoms, which measures the relative amounts of different carbon atoms. More than 98 per cent of all carbon atoms have a mass of 12 atomic mass units, but a few carbon atoms are heavier, with a mass of 13 or 14 atomic mass units.

“Living matter preferentially consists of the lighter carbon atoms because they take less energy to incorporate into cells,” said Yakymchuk. “Based on the increased amount of carbon-12 in this graphite, we concluded that the carbon atoms were once ancient life, most likely dead microorganisms such as cyanobacteria.”

The graphite is found in rocks older than 2.5 billion years ago, a time on the planet when oxygen was not abundant in the atmosphere, and life existed only in microorganisms and algae films.

During this study, Yakymchuk’s team discovered that this graphite not only links the gemstone to ancient life but was also likely necessary for this ruby to exist at all. The graphite changed the chemistry of the surrounding rocks to create favourable conditions for ruby growth. Without it, the team’s models showed that it would not have been possible to form rubies in this location.

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