Many theories have been put forward about when life started on Earth, but no concrete evidence was found. Now researchers have presented a new discovery which states that life had already come on Earth 4.2 billion years ago. Scientists have found out about the last universal ancestor, or Last Universal Common Ancestor (LUCA) on the basis of the genome of present-day organisms. This ancestor must have come into existence 4.2 billion years ago.

According to this, life had come on Earth in the initial phase of this planet. Because the time of Earth’s existence is said to be 4.5 billion years ago. This study has been published in Science Alert. Sandra Álvarez-Carretero, a biologist associated with this discovery, says that she had not at all guessed that LUCA would be so old, and would have come into existence only a few hundred years after the formation of the Earth.

Talking about the time of formation, the atmosphere of the Earth at that time must have been completely different. If compared to today’s time, it must have been very poisonous. Oxygen, which is the most important element for almost every organism living on Earth at present, its availability on Earth must have come much later. This time is said to be 3 billion years ago. That is, life on Earth had come much before oxygen.

Fossils of even the tiniest of microscopic organisms are said to be 3.8 billion years old. But scientists here believe that the environment necessary to support life on Earth was created 4.3 billion years ago. But it has also been said that the geological and biological processes of the Earth pose an immense challenge to explore life of such an old time. That is, it is almost impossible to gather evidence of life at that time.

Here the team of scientists took the help of new resources called genomes of living organisms. Along with this, fossil records have also been explored for this. Scientists have tried to understand how LUCA would have survived in the environment of that time. It would have been a single-celled organism that would not have even had a nucleus, and it would have been dependent on non-oxygen based metabolic processes to make acetate.