Life may have originated in deep-sea hydrothermal vents

The theory proposes that the primordial life-forms that gave rise to all life on Earth left deep-sea vents because of their "invention" of a tiny pump.

These primitive cellular pumps would have powered life-giving chemical reactions, LiveScience reported.

The idea could help explain two mysteries of life's early origin: How did the earliest proto-cells power chemical reactions to make the organic building blocks of life; and how did they leave hydrothermal vents to colonise early Earth's oceans?

Authors of the theory in the journal Cell argue the environmental conditions in porous hydrothermal vents - where heated, mineral-laden seawater spews from cracks in the ocean crust - created a gradient in positively charged protons that served as a "battery" to fuel the creation of organic molecules and proto-cells.

Later, primitive cellular pumps gradually evolved the ability to use a different type of gradient - the difference in sodium particles inside and outside the cell - as a battery to power the construction of complex molecules like proteins. And, the proto-cells could leave the deep-sea hydrothermal vents.

Now, study co-author Nick Lane, a researcher at the University College London and William Martin, of the Institute of Molecular Evolution at the Heinrich Heine University in Germany, propose that the rocky mineral walls in ocean-floor vents could have provided the means for early life.

"At the time of life's origin, the early ocean was acidic and filled with positively charged protons, while the deep-sea vents spewed out bitter alkaline fluid, which is rich in negatively charged hydroxide ions," Lane told the website.

"The vents created furrowed rocky, iron- and sulfur-rich walls full of tiny pores that separated the warm alkaline vent fluid from the cooler, acidic seawater. The interface between the two created a natural charge gradient. It's a little bit like a battery," Lane said.

That battery then powered the chemical transformation of carbon dioxide and hydrogen into simple carbon-based molecules such as amino acids or proteins.

Eventually that gradient drove the creation of cellular membranes, complicated proteins and ribonucleic acid (RNA), a molecule similar to DNA.

At that point, primitive cells used the thin, serpentine walls of the vent to corral the new carbon-based molecules together into precursors of cells and used the charge gradient in the environment to power the building of more complex organic chemicals, researchers believe.