Did Life Begin From Electrical Charges Deep Beneath the Sea?

A black smoker Exciting new research shows that hydrothermal vents on the deep ocean floor, believed by many to be the cradle for early life,  generated electrical currents that could have helped generate the complex carbon-based molecules that came together to produce life, as well as provide it with a power supply. Four billion years ago, such vents would have been the ideal hatcheries for life, as they provide essentially all the requirements needed for sustained abiotic chemistry and the beginnings of natural selection.

A team led by Ryuhei Nakamura at the University of Tokyo in Japan have uncovered evidence that such vents can generate electrical currents as well as bringing minerals containing iron, copper and sulphur from deep inside the Earth's crust to the seabed.

These minerals possess an excess of electrons, so Nakamura's team wanted to find out whether these electrons could generate an electric current in the vent by conducting lab-based electrical experiments on a type of sulphur-rich chimney known as a black smoker extracted from a hydrothermal vent in the middle of the South Pacific Ocean.

First, the team passed a current through the chimney wall to show that it could conduct electricity. They then simulated the conditions at a hydrothermal vent by pumping hot, sulphur-rich water past one side of a chimney wall, and cold, salty water past the other, which generated a weak but steady electrical current across the chimney wall. 

The team found that the chimney walls catalyse the conversion of sulphides into elemental sulphur as the hot vent fluid travels through them. The reaction releases electrons which pass through the wall to the salt water outside, where they convert dissolved oxygen into hydrogen peroxide generating the electrical current that could provide a source of energy for bacteria.

Nakamura believes that carbon dioxide took the place of oxygen, converting directly into carbon-based molecules, making complex organic molecules on the early Earth's sea floors and the chemical building blocks of life.

Their next big challenge will be to confirm that black smokers generate electricity when they are at the bottom of the ocean, not just in the lab.

Casey Kazan via newscientist.com and microbeworld.org

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