4.2 Billion Years of the Human Evolution - From LUCA to Homo Sapiens

4.2 Billion Years of the Human Evolution - From LUCA to Homo Sapiens Music: Richard Wagner - Ride of the Valkyries; By studying the genomes of living organisms, scientists have determined that the last universal common ancestor (LUCA), or the first organism that gave rise to life, appeared as early as 4.2 billion years ago. This study was published in Nature Ecology & Evolution in 2024 under the title “The nature of the last universal common ancestor and its impact on the early Earth system“. The study has 19 author scientists, including Edmund R. R. Moody and Sandra Álvarez-Carretero. For reference, the Earth began to form about 4.6 billion years ago and finished forming all its layers billion years ago. This means that life first appeared when the planet was only 400 million years old. “We didn’t think LUCA would be so old. Nevertheless, it is a fact, and our research is in line with other modern views,“ said evolutionary biologist Sandra Alvarez-Cartero. In the “young“ Earth was very different from today. Earth’s atmosphere at that time would have been poisonous to us, and oxygen in the quantities we need now appeared relatively late, only 3 billion years ago. However, life originated much earlier. At the moment, fossils dating back billion years can be found on Earth. Nevertheless, researchers believe that life existed on Earth 4.2 billion years ago. And yet no direct traces of such ancient life can be found. Erosive, organic and geological processes take place on the planet, which erases the ancient traces. It was this problem that Edmund Moody, a phylogeneticist from the University of Bristol, wanted to solve. His group was looking for ancient traces of life using a different method. Their research is based on the “molecular clock“. With this method, we can estimate the rate of occurrence of mutations and determine how much time has passed since this or that organism arose. All organisms, from simple microbes to fungi, have something in common. There is a universal genetic code. For example, how we make protein is common to all organisms. There is an almost universal set of 20 amino acids, which are distributed in the same way in all living species. Accordingly, all living organisms use adenosine triphosphate (ATP) as a source of energy in their cells. Based on these similarities and differences, Moody and his colleagues determined how long it had been since the LUCA successors began to divide. Moreover, using complex evolutionary modeling, they were able to learn more about LUCA itself—researchers determined what LUCA would have looked like and how it survived such extreme conditions. They found that LUCA was very similar to a prokaryote, a single-celled organism that does not have a nucleus. It should not have been dependent on oxygen, as there was a serious shortage of oxygen on the planet at the time. However, that’s not all. Apparently, LUCA was not alone. “Our study showed that LUCA was a complex organism that was not so different from modern prokaryotes, although it had an immune system. This means that our ancient ancestor was fighting viruses even 4.2 billion years ago,“ said Davide, a phylogeneticist and one of the authors of the study. Davide Pisani. LUCA’s metabolic processes produced waste products, and this is how the first viruses could have emerged. This means that in the evolutionary system of the planet, a complete ecosystem took relatively less time to discover and develop. This is also noted in the study, which reads as follows: “The results show how quickly ecosystems formed on early Earth. This suggests that life on other planets (given the right conditions) would have flourished even faster.“ ცოცხალი ორგანიზმების გენომის შესწავლით, მეცნიერებმა დაადგინეს, რომ ბოლო უნივერსალური საერთო წინაპარი (LUCA), ანუ პირველი ორგანიზმი, რომელმაც სიცოცხლეს სათავე დაუდო, ჯერ კიდევ 4.2 მილიარდი წლის წინ გაჩნდა. აღნიშნული კვლევა 2024 წელს Nature Ecology & Evolution-ში გამოქვეყნდა სათაურით “The nature of the last universal common ancestor and its impact on the early Earth system“. კვლევას 19 ავტორი მეცნიერი ჰყავს, მათ შორის არიან ედმუნდ მუდი (Edmund R. R. Moody) და სანდრა ალვარეს-კარეტერო (Sandra Álvarez-Carretero). ცნობისთვის, დედამიწამ ჩამოყალიბება დაახლოებით 4.6 მილიარდი წლის წინ დაიწყო და მილიარდი წლის წინ თავისი ყველა შრის ფორმირება დაასრულა. ეს ნიშნავს, რომ სიცოცხლე პირველად მაშინ გაჩნდა, როდესაც პლანეტა სულ რაღაც 400 მილიონი წლის იყო. “ჩვენ არ გვეგონა, რომ LUCA ასე ძველი იქნებოდა. მიუხედავად ამისა, ეს ფაქტია და ჩვენი კვლევა სხვა თანამედროვე შეხედულებებთან თანხვედრაშია“, — გ