Revealed: how ancient slime left oceans to colonise land
One of nature's greatest secrets - how ocean slime turned the world green with vegetation - has been uncovered by scientists.
Ancient algae were already genetically programmed to survive out of water before colonising the land and evolving into the plants that transformed life on Earth.
The big change 450 million years ago dramatically altered the climate and set the stage for the terrestrial evolution that ultimately led to the human race.
Scientists already knew that plant life was only able to take root on the land by forming symbiotic relationships with microscopic fungi.
But how the algae survived long enough on dry land to evolve a microbiotic partnership has been a mystery.
The answer appears to be that they already possessed the genetic programming necessary for the transition before even leaving the water.
Dr Pierre-Marc Delaux, from the John Innes Centre in Norwich, said: "At some point 450 million years ago, algae from the Earth's waters splashed up on to barren land.
"Somehow it survived and took root - a watershed moment that kick-started the evolution of life on earth. Our discovery shows for the first time that the algae already knew how to survive on land while still in the water. Without the development of this pre-adapted capability in algae, the earth could be a very different place today.
"This finding has filled a gap in our collective knowledge about the origins of life on earth."
The research is reported in the journal Proceedings of the National Academy of Sciences.