Evolutionary biology assumes that all organisms living today have a common ancestor. This is because today’s organisms have many similarities, including the fact that they use the same genetic code. An international research team has now presented new findings on this potential common ancestor, called LUCA, which stands for „Last Universal Common Ancestor“. This common ancestor of all living beings today is thought to have lived much earlier than previously assumed, namely around 4.2 billion years ago.
An international research team led by the University of Bristol in England traced the family tree of species back to their presumed beginnings: according to the study, this was a single-celled organism similar to today’s bacteria.
Previously, LUCA was thought to be no more than 3.9 billion years old. This is because early life would probably not have survived the so-called „late heavy bombardment“, in which numerous celestial bodies hit the Earth around 4 billion years ago. However, recent studies suggest that these impacts may have been less violent than assumed. If so, the last common ancestor could have lived much earlier.
The team compared all the genes in the genomes of the living species and counted the mutations that have occurred over time – since the common ancestor LUCA. The mathematical calculation of the genetic speed came to the conclusion that LUCA must have lived 4.2 billion years ago, around four hundred million years after the formation of the Earth and our solar system.
LUCA probably resembled modern single-celled organisms such as bacteria, as co-author Davide Pisani noted: „But what’s really interesting is that it clearly had an early immune system, which shows that our ancestor was already involved in an arms race with viruses 4.2 billion years ago.“
Co-author Tim Lenton from the University of Exeter adds: „It’s clear that LUCA used and modified its environment, but it’s unlikely that it lived alone.“ Its waste could have been food for other microorganisms that produced methane and thus contributed to the development of a recycling ecosystem.
To the press release of the University of Bristol and the original study: July: LUCA | News and features | University of Bristol
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Der Stammbaum des Lebens: Von LUCA stammen Bakterien, Einzeller (Eukaryoten) und eine weitere Gruppe von Mikroorganismen, die Archäen, ab. Foto: https://commons.wikimedia.org/wiki/File:LUCA_and_LECA_McGrath_2022.jpg
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