For 80 years it has been accepted that early life began in a ‘primordial soup’ of organic molecules before evolving out of the oceans millions of years later. Today the ’soup’ theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth’s chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.

“Textbooks it that life arose with organic soup and the first cells were increased by the fermentation of this organic material to produce energy in the form of ATP. We offer a new perspective on why From this point of view old and familiar will not work at all, “said team leader Dr Nick Lane of the University College London.” We present an alternative that life arose from gas (H2, CO2, N2, H2S) and energy for life first came to mobilize geochemical gradients created by Mother Earth, to a particular type of Deep-sea hydrothermal vent – one that is riddled with small compartments or interconnected pores.

The soup theory was proposed in 1929, when JBS Haldane published his influential essay on the origin of life in which he argued that the UV radiation provided the energy to convert methane, l ‘ ammonia and water in the first organic compounds in the oceans of early Earth. But critics point to the soup theory that there is no sustained driving force to react to anything, and no source of energy, life as we know it can not exist.

“Despite weaknesses bioenergetic and thermodynamic 80 years old concept of the primordial soup is the center of the mainstream thinking on the origin of life,” said lead author, William Martin, an evolutionary biologist of the Insitute of Botany III in Düsseldorf. “But the soup has no capacity to produce vital energy for life.”

In rejecting the theory of the soup of the team turned to the chemistry of the Earth to identify the source of energy that could power the predecessors first primitive living organisms: the geochemical gradients through a labyrinth of natural caves near microscopic hydrothermal vents. These cells generated catalytic lipids, proteins and nucleotides, which may have led to the first true cells.

The team focused on the ideas launched by the geochemist Michael J. Russell, on the alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today – a proton gradient through a membrane. Initially the organizations that could use these degraded by a process called chemiosmosis in which the proton gradient is used to drive the synthesis of the universal energy currency, ATP, or equivalent simpler. Later on the cells evolved to generate their own proton gradient by electron transfer from a donor to an acceptor. The team argue that the biggest donor was the hydrogen acceptor was first CO2.

“The cells of modern life have inherited the same size gradient of protons, and, especially, in the same direction – inside and outside the positive and negative – as the inorganic vesicles from which they were committed” said co-author John Allen, a biochemist at Queen Mary, University of London.

“Constraints chemiosmosis thermodynamic means is strictly necessary for the carbon and energy metabolism in which all organisms develop from simple chemical ingredients [Autotrophy] today, and probably the first free-living cells,” said Lane. “Here we see how the first cells may have exploited a strong geochemical created and then learned to their own.”

It was a vital transition as chemiosmosis is the only mechanism by which organisms can not escape vents. “The reason that all agencies are chemiosmotic today is simply that they have inherited from the time and place that the first cells evolved – and they could not have evolved without it” said Martin.

“Far from being too complex to be fed early in life, it is almost impossible to see how life could have begun without chemiosmosis,” said Lane. “It is time to shake off the yoke of fermentation in the primordial soup that” life without oxygen “- an idea that goes back to a time before anyone had any biological understanding of how ATP is made.”

from:sciencedaily.com