Evrim Yazgin
Cosmos science journalist
Scientists believe they are beginning to understand the conditions which sparked life on Earth by demonstrating in the lab a massive multiplication of DNA in just minutes.
More than 4 billion years ago, chemical compounds came together to form life.
This event occurred when earth was very young – just a few hundred million years old. At the time, Earth was being bombarded with asteroids. Much of the surface was molten. This earliest part of our planet’s history is aptly named the Hadean, after the ancient Greek god of the dead and king of the underworld.
But the Hadean also saw the development – once Earth cooled – of our atmosphere and oceans. It was in these first oceans that scientists theorise the “primordial soup” of carbon-based chemical compounds first came together to form the building blocks of life.
Which conditions allowed this process to take place has remained a mystery.
New research published in the journal eLife describes evidence which suggests that a simple geophysical setting could have led to the building blocks of life.
A gas flow over a narrow channel of water can create a physical environment, the researchers say, that leads to the replication of nucleic acids – the information storage biomolecules which make up DNA and RNA.
Life doesn’t just need nucleic acid replication. It also requires that RNA strands separate again after the replication process – something that is difficult given the conditions needed for replication in the first place.
“Various mechanisms have been studied for their potential to separate DNA strands at the origin of life, but they all require temperature changes that would lead to degradation of nucleic acids,” says lead author Philipp Schwintek, a Ph.D. student at Ludwig-Maximilians-Universität München, Germany.
“We investigated a simple and ubiquitous geological scenario where water movement through a rock pore was dried by a gas percolating through the rock to reach the surface,” Schwintek explains. “Such a setting would be very common on volcanic islands on early Earth which offered the necessary dry conditions for RNA synthesis.”
The team uncovered the process by building a laboratory model of an ancient setting on Earth featuring a rock pore, water flow and gas flow.
They found an accumulation of DNA strands at the interface between water and gas.
Within 5 minutes, there was 3 times as much DNA as at the start of the experiment. After an hour, the amount of DNA had multiplied by 30.
