Meet Luca: The common ancestor of all life on Earth

JULY 26, 2016

by Chuck Bednar

By surveying nearly 2,000 genomes belonging to modern-day microbes, an international group of researchers has purportedly discovered that the last universal common ancestor of all life on Earth was a heat-loving, hydrogen-consuming organism that emerged 3.8 billion years ago.

In the study, which was published Monday in the journal Nature Microbiology, William Martin from the University of Dusseldorf in Germany and his colleagues reveal that life on Earth likely formed around hydrothermal vents, such as those found near undersea volcanoes, where heated water that was rich in hydrogen, carbon dioxide, and minerals could be found.

While the exact chemical events that resulted in the origin of life on Earth will likely never be fully understood, Science explained that some of the earliest living organisms have left behind fragments of themselves in the genes passed on to their descendants. Martin’s team of researchers analyzed these genes as they hunted for clues pertaining to the daily life of our last universal common ancestor – LUCA, for short.

They found that LUCA was likely a microbe that fed on hydrogen gas and lived in an oxygen-free environment, indicating that it was probably born in hydrothermal vents. They also discovered that it possessed 355 proteins which are now nearly universally found in the bacteria and archaea that eventually developed from it, but as New Scientist pointed out, it was also quite different in many ways.

Organism was unable to produce its own energy; relied on its surroundings for help

Martin’s team analyzed the genomes of 1,800 bacteria and 130 archaea, the website explained, and their analysis revealed that, unlike those organisms, LUCA most likely was unable to pump ions across membranes to create an electrochemical gradient in order to produce the energy-rich molecule ATP. Rather, it harnessed an existing gradient in order to produce ATP.

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