Researchers have found that the ancestor of ALL living BEINGS on Earth was a single-cell, bacterium-like organism that is estimated to have lived some 4 BILLION years ago when our planet was in its infancy, with an age of around 560 million years.
The discovery sharpens the debate between scientists who on one hand believed life as we know it began in a completely hostile and extreme environments like deep sea vents, or in the vicinity of volcanoes, and between those researchers who are more in favor of life coming into existence near ‘warm little ponds’ as proposed by Darwin.
His name is LUCA,”Ultimate Last Common Ancestor”, and it is the organism from which all living things on earth descend from.
For decades, researchers have tried to determine the characteristics of this exceptional being, and the mechanisms that allowed him to “brand” and propagate life as we know it.
Now, thanks to a new study by a group of German researchers published in the “Nature Microbiology“, we are closer than ever to obtain a genetic portrait of the ancestor of all living things on our planet.
According to the study, our first ancestor was a very simple organism and probably lived about 4,000 million years ago near a hydrothermal vent on the bottom of one of Earth’s primitive oceans.
The ‘portrait’ of LUCA was obtained after study and systematic classification of more than six million genes, from which researchers extracted 355 which they believe may have belonged to LUCA, the joint ancestor of bacteria and archaea.
To get to the bottom of this, the team led by William Martin, of the German Heinrich Heine University, focused on the genes of the two largest (and oldest) groups of unicellular organisms that exist: bacteria and archaea. According to “Nature Microbiology” LUCA is very likely to have belonged to one of two of the above-mentioned families.
The finding has “significantly advanced our understanding of what Luca did for a living,” James O. McInerney of the University of Manchester wrote in a commentary, and provides “a very intriguing insight into life four billion years ago.”
LUCA; As SIMPLE as it gets
The 355 genes discovered by researchers suggests that LUCA was a very simple organism that could survive without oxygen, obtaining energy from carbon dioxide, hydrogen and other hot gasses expelled from Earth through fissures in the earth’s crust in the ocean floor.
In addition to the above, LUCA also had an enzyme that allowed it to survive near very high temperatures, even several hundreds of degrees, and that made it dependent on metallic elements such as iron.
Similar organisms are still abundant today, and it is curious to think that their existence was considered as impossible by scientists until just forty years ago when it was still thought that all life forms needed light and oxygen in order to survive.
Even though LUCA is our oldest ancestor, it doesn’t necessarily make him the first living being on Earth, but the luckiest of all which managed to survive and to cling on to become the “father” of all living beings that inhabit our planet today.