When did life start on Earth? Scientists say it was 4.2 billion years ago
The DNA inside all organisms alive today, from E. coli to blue whales, has many similarities, which suggests it can all be traced back billions of years to LUCA.
A new study has suggested that life on Earth emerged much earlier than previously thought. According to the study, the Last Universal Common Ancestor (LUCA), the first organism that spawned all the life that exists today on Earth, emerged as early as 4.2 billion years ago.
New Scientist
Common traits with LUCA and creatures now
The DNA inside all organisms alive today, from E. coli to blue whales, has many similarities, which suggests it can all be traced back billions of years to LUCA. The researchers estimate that 2,600 protein-coding genes can be traced back to LUCA, whereas some previous estimates are as low as 80.
Also read: This Ancient Molecule Is The Root Cause Of All Life On Earth
LUCA emerged soon after Earth formed
The team also concludes that LUCA lived around 4.2 billion years ago ¨C much earlier than other estimates, and surprisingly close to the formation of Earth 4.5 billion years ago.
"We did not expect LUCA to be so old, within just hundreds of millions of years of Earth formation," says evolutionary biologist Sandra ?lvarez-Carretero of the University of Bristol in the UK. "However, our results fit with modern views on the habitability of early Earth."
Science How
How LUCA shaped life
Genes that today are found in all the main branches of life may have been passed down in an unbroken line all the way from LUCA, allowing us to work out what genes the ancient ancestor possessed.
Also read: Lightning Strikes Could Have Sparked Life On Earth, New Study Claims
Live Science
Back when it was new, Earth was a very different place, with an atmosphere that we would find extremely toxic today. Oxygen, in the amount current life seems to need, didn't emerge until relatively late in the planet's evolutionary history, only as early as around 3 billion years ago.
The results also suggest LUCA had a primitive version of the bacterial defense system known as CRISPR, to fight off viruses. ¡°Even 4.2 billion years ago, our earliest ancestors were fighting off viruses,¡± says team member Edmund Moody, also at the University of Bristol.
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