According to a new study, the first thing on our planet appeared 100 million years earlier than previously thought.
About 3.9 billion years ago - right after Earth was attacked by Theia and while it was still facing a series of meteors - the ancestors of all living creatures were born.
Scientists have traditionally used fossil records to track the origin of life on Earth, but the further away the past, the harder it is to find this result.
Dr. Holly Betts of the University of Bristol, the lead author of the study, explains: 'The problem with the first fossil record of living things is that it is very limited and difficult to interpret - careful analysis of some The oldest fossil has shown them to be crystals, not fossils'.
Life on Earth cannot be longer than 4.5 billion years.
In the study published in the journal Ecology and Natural Evolution, Ms. Betts and colleagues used a combination of fossil and genetic data to find the so-called 'Luca' - the common common ancestor. Last variable.
Co-author Professor Philip Donoghue said: "Fossils do not represent the only evidence line to understand the past."
'The second record of life existed, preserved in the genome of all living things.'
By combining data from all available sources, scientists can build 'molecular clocks' , based on the idea that proportional differences in genetic code between different species are proportional. with time since they shared common ancestors.
Using information on 29 genes from a total of 102 living organisms, the team assembled a timeline of dates of all major organisms such as bacteria.
Scientists concluded that Luca assumed to exist before the "heavy bombardment" when many meteors hit the Earth.
This is earlier than the oldest fossil evidence of life - evidence of no more than 3.8 billion years old.
While there are still uncertainties, scientists know that life on Earth cannot be longer than 4.5 billion years, when Theia crashed into the young planet.
This devastating event not only destroyed the Earth but ultimately helped create the Moon, it had the effect of clearing the planet and killing any life that existed there.
Because the first life consists of tiny microscopic cells, residual fossils are rarely found, and they are the source of many debates.
Some people have suggested that carbon found in a mineral with a life of 4.1 billion years old is known to be evidence of ancient life, but this has not been confirmed.