It has long been theorised that life first evolved in the ocean, but it was not known how the "primordial molecules" delivered to Earth by asteroids as raw amino acids, could have undergone the complex reactions required to form proteins.
Life is dependent on the formation of proteins, and the exact way in which this first occurred in abundance has long been a riddle to chemists.
This is because the peptide-forming reaction, which creates the strings of amino acids required to form proteins, and therefore organisms, requires water. But it also requires the chemical loss of a water molecule – something scientists previously believed was tricky in a largely sea-covered world.
But now, this conundrum has been addressed for the first time in research by US scientists, who say that places where "water isn’t wet", are where this reaction can take place.
This means that in places where liquid water meets the atmosphere, such as water droplets in the form of ocean spray, could provide the ideal conditions for these vital chemical reactions to take place.
"This is essentially the chemistry behind the origin of life,” said Graham Cooks, from Purdue University in Indiana in the US.
“This is the first demonstration that primordial molecules, simple amino acids, spontaneously form peptides, the building blocks of life, in droplets of pure water. This is a dramatic discovery.”
“Water isn’t wet everywhere,” Dr Cooks said.
On the margins of our water world, where the water droplet meets the atmosphere, "incredibly rapid reactions can take place", the team said, transforming amino acids into the building blocks of life.
"Places where sea spray flies into the air and waves pound the land, or where fresh water burbles down a slope, were fertile landscapes for life’s potential evolution,” he said.
The team at Purdue spent more than 10 years using mass spectrometers to study chemical reactions in droplets containing water.
“The rates of reactions in droplets are anywhere from a hundred to a million times faster than the same chemicals reacting in bulk solution,” Dr Cooks said.
They said their discovery could also lead to the faster development of drugs to treat humanity’s most debilitating diseases.
“If you walk through an academic campus at night, the buildings with the lights on are where synthetic chemists are working,” Dr Cooks said.
“Their experiments are so slow that they run for days or weeks at a time. This isn’t necessary, and using droplet chemistry, we have built an apparatus, which is being used at Purdue now, to speed up the synthesis of novel chemicals and potential new drugs.”
The team said their findings would also help inform scientists searching for whether life could form on other planets and moons.
The research is published in the Proceedings of the National Academy of Sciences.