Scientists have long sought to pinpoint when the last universal common ancestor (LUCA) lived, and a new study suggests it was much earlier than previously thought – around 4.2 billion years ago. This ancient cell is the ancestor of all living things on Earth today.
LUCA wasn’t significantly different from complex bacteria that exist today, and it thrived in an ecosystem teeming with other species, viruses, and microorganisms. Researchers found evidence of an early immune system, indicating that LUCA was engaged in an “arms race” with viruses as far back as 4.2 billion years ago.
The study also revealed that LUCA likely lived in an ocean environment, a shallow hydrothermal vent, or a hot spring, and could tolerate extreme temperatures and lack oxygen. Instead, it relied on the waste products of other microorganisms for energy.
LUCA’s metabolic pathways suggest it may have used organic material already broken down by other microbes for energy, further supporting the idea that life was flourishing in a thriving ecosystem even then.
The study’s findings have implications for the search for extraterrestrial life. As Philip Donoghue, a professor of paleobiology at the University of Bristol, said: “This suggests that life may be flourishing on Earth-like biospheres elsewhere in the universe.”
Source: https://www.livescience.com/animals/meet-luca-the-4-2-billion-year-old-cell-that-s-the-ancestor-of-all-life-on-earth-today