Patrick Boehnke, working in Harrison’s lab, said “If all life on Earth died during this bombardment, which a few scientists have argued, then life must have restarted quickly”. They said that the discovery of the organisms suggests that living organisms were present on Earth at least 4.1 billion years ago.
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“Evidence from Hadean zircons has provided a new picture of a much more hospitable planet more like the Earth of today in many respects”, said Elizabeth Bell, the lead author of the study, to the Royal Society of Chemistry.
Scientists have found fossil-like hints that a few kind of life existed on Earth 4.1 billion years ago – when the planet was a mere volcanic toddler.
The other grain, a 4.1 billion year old sample, was subjected to carbon isotope analysis using mass spectrometry. That’s 300 million years earlier for life to pop up than previously thought. According to a report published in pressherald.com, more than 10,000 of the zircons were analysed by Harrison and his team that can be dated back to 4.1 billion years.
According to Harrison, a professor of geochemistry at UCLA, life doesn’t take long to spring up if the conditions and ingredients are right. What makes them special is they preserve their immediate environment.
79 zircons that contained dark specks were closely analyzed by the scientists with Raman spectroscopy where the technique allowed them to see the molecular as well as the chemical structure of microorganisms in 3 dimensions.
Scientists found that one of the zircons studied contained graphite and pure carbon at two different locations.
Researchers examined tiny grains of the mineral zircon from western Australia’s Jack Hills and chemically dated them to when Earth was barely 400 million years old.
But what if life had begun before the heavy bombardment?
Harrison also goes on to say, “There is no better case of a primary inclusion in a mineral ever documented, and nobody has offered a plausible alternative explanation for graphite of non-biological origin into a zircon”. The graphite must be older than the zircon in which it has been entombed, though the researchers do not know how much older.
Not only does the graphite point to life, but its specific ratio of carbon-12 to carbon-13 is the fingerprint of photosynthesis, say the researchers, because a few enzymes “prefer” carbon-12. But the notion that life could have existed during Earth’s earliest period certainly warrants follow-up studies.
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“We need to think differently about the early Earth”, Bell said.
