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Looking for LUCA, the Last Universal Common Ancestor
Context: In a new study, scientists have said the last universal common ancestor (LUCA) could have formed just 300 million years after the earth formed.
LUCA and the Molecular Clock:
- Researchers believe that all three branches of life (bacteria, archaea, and eukarya) originated from a single cell called the last universal common ancestor (LUCA).
- There is no direct fossil evidence for LUCA, but the fact that modern genomes share many common features provides insights into its biology.
- The theory of the molecular clock, proposed in the 1960s, suggests that the rate of acquiring new mutations is constant, allowing researchers to estimate the time between evolutionary events.
Which is Older: LUCA or Fossils?
- Researchers at the University of Bristol and Exeter estimated that LUCA originated around 4.2 billion years ago using a molecular clock.
- LUCA may have had a small genome with around 2.5 million bases encoding approximately 2,600 proteins, sufficient for survival in a unique environmental niche.
- The metabolites produced by LUCA could have created a ‘secondary’ ecosystem for other microbes to emerge.
- The origin of LUCA at 4.2 billion years significantly predates previous estimates of the origin of life on Earth.
- Fossil records of the earliest life-forms found in the Pilbara Craton in Western Australia suggest life emerged around 3.4 billion years ago.
- The study’s findings push this date back by almost a billion years.
- LUCA may have had genes responsible for immunity, indicating it had to fight off viruses.
- These findings are significant for understanding how life emerged and evolved on Earth and could aid in searching for life across the universe.
- Insights into evolution could boost efforts to engineer synthetic organisms for various industrial, chemical, and biological processes on Earth and aid in creating or moderating ecosystems on other planets.
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Theories on the Origin of Life on Earth:
Significance and Current Understanding:
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