News Excerpt:

The 'Candelabra' hydrothermal vent on the Mid-Atlantic Ridge, situated 3.3 km underwater, has provided scientists with evidence of ancient life forms in the precipitates around such vents.

LUCA and the Molecular Clock:

• Researchers believe bacteria, archaea, and eukarya all originated from the last universal common ancestor (LUCA).

• There is no fossil evidence of its existence, but the fact that modern genomes share so many features provides some clues.

• The molecular clock theory, proposed by Emile Zuckerkandl, Linus Pauling, and later improved by Motoo Kimura, helps scientists reconstruct the 'tree of life'.
• The molecular clock theory suggests that the rate of genetic mutations is constant over time, allowing researchers to estimate the time between evolutionary events by comparing genome sequences and fossil records.

Mystery Around origin of life:

• The origin of life on earth is one of the world’s most enduring mysteries.
• Competing theories exist, but none have conclusive proof.

• Scientists widely believe that a combination of geological, climatic, and chemical processes gave rise to the building blocks of life.

Oparin-Haldane hypothesis: 

• In the 1920s, Alexander Oparin and J. B. S. Haldane independently proposed origin theories.
• They suggested that the first molecules making up the earliest life forms gradually self-organized from a “primordial soup” in a young earth’s prebiotic environment.
• This idea is known as the Oparin-Haldane hypothesis

Miller-Urey experiment:

• The famous Miller-Urey experiment 1952 showed that under the right conditions, inorganic compounds could give rise to complex organic compounds.
• This experiment demonstrated that amino acids, the building blocks of proteins, could be created from a mixture of methane, ammonia, and water subjected to an electric current.

Extra-terrestrial Source:

• Other theories propose that meteorites could have brought the building blocks of life to earth.

• Discoveries of extraterrestrial organic material and amino acids on asteroids support this idea.

Recent Findings on LUCA

• As per recent study in Nature Ecology and Evolution, researchers constructed a phylogenetic tree of bacterial and archaeal genomes, estimating that LUCA originated around 4.2 billion years ago, just 300 million years after the earth formed.

• The study suggests that LUCA had a small genome with about 2.5 million bases encoding around 2,600 proteins.

• LUCA's metabolites may have created a 'secondary' ecosystem for other microbes to emerge. 
• These findings push the date of life on earth back by almost a billion years, predating the earliest fossil records by a significant margin.
• The researchers also speculate that LUCA had genes for immunity, indicating it faced viral threats.

Conclusion:

These findings are crucial not just for understanding the origins and evolution of life on earth, but also for searching for similar life forms elsewhere in the universe. Insights into LUCA's evolution could enhance human efforts to engineer synthetic organisms and create or moderate ecosystems on other planets in the future.