Scientists caution that our understanding of LUCA is still evolving.
Scientists have rewritten the history of life on Earth with a new estimate for the age of LUCA, or the Last Universal Common Ancestor, who is generally acknowledged as the common ancestor of all living things, thanks to a ground-breaking study.
The study, which was published in Nature Ecology & Evolution, indicates that LUCA lived approximately 4.2 billion years ago, which is significantly closer to Earth's origin than previously thought.
LUCA, a common ancestor to all organisms and not the first life form, has been a controversial topic among scientists for centuries. Life fossil evidence goes back as far as 3.4 billion years, yet this study proposes that LUCA might be close to being the same age as the Earth. The genetic code and DNA replication, which are two of the vital biological processes, might have developed almost immediately after the planet was formed.
The research team performed analysis of 700 genomes of bacteria, archaea, and fungi and constructed LUCA's genome, excluding eukaryotes such as plants and animals that evolved later. They have found 57 gene families responsible for the evolutionary relationships of those organisms in their study.
Their results depict LUCA as a very intricate organism, a kind of modern bacteria or archaea that does not possess the capability of photosynthesis. The study proposed a new way of finding LUCA's age using paralogous genes and fossil data to solve the problem of so little direct fossil evidence of the early days of Earth.
This LUCA reconstruction represents a significant advancement in understanding the evolution of living organisms on Earth. Nevertheless, the research work has made sure that their deductions are not the last ones. With new organisms being discovered and technology developing, it is very likely that our interpretation of LUCA will develop, furthermore to the point of giving our knowledge more depth at the ancient beginnings of life.