The ocean was turned into a global mega-organism 3 billion years ago before giving birth to the ancestors of all living things today, a new study has revealed.
This single organism has been called LUCA and is now traceable in all domains of life including plants, animals and fungi.
According to Gustavo Caetano-Anolles of the University of Illinois, LUCA was an enormous "mega-organism" that filled the planet’s oceans before splitting into three and giving birth to the ancestors of all living things today.
It was the result of early life’s fight to survive, which turned the ocean into a "global genetic swap shop" for hundreds of millions of years.
Cells that were struggling to survive on their own exchanged useful parts with each other without competition, creating the "mega-organism".
Scientists believe that it was about 2.9 billion years ago when LUCA split into the three domains of life, namely bacteria, archaea and eukaryotes, but little is known about what happened before the split.
According to Caetano-Anolles, early cells must have shared their genes and proteins with each other in order to survive, and that molecules that were new and useful would have been passed between cells without competition and gone global.
“It was more important to keep the living system in place than to compete with other systems,” the Daily Mail quoted Caetano-Anolles as saying.
This free exchange and lack of competition meant that the ocean functioned as the “single mega-organism”, which was only broken apart when some of the cells evolved ways of producing everything they needed.
Once this happened, the Earth changed forever and all living things of today were born.
The study has been published in New Scientist.