Scientists have traced the origin of life on Earth to a single ancestor, called the Last Universal Common Ancestor (LUCA), that emerged approximately 4.2 billion years ago. This discovery was made by analyzing the genomes of modern organisms.
Early Earth had a very different atmosphere, toxic by today’s standards. Oxygen, crucial for current life forms, only appeared much later, around 3 billion years ago. Despite this, life emerged even earlier, with microbial fossils dating back to 3.48 billion years. Scientists believe conditions on early Earth could have supported life as early as 4.3 billion years ago.
The researchers studied the genomes of living organisms and the fossil record to learn more about LUCA. They found that LUCA was a primitive, single-celled organism without a nucleus, relying on non-oxygen-based metabolic processes. It likely had a basic immune system and lived in a larger ecosystem.
This research suggests that LUCA was not a simple organism, but a complex one with a rudimentary immune system. It also implies that ecosystems can develop quickly in a planet’s early history. These findings have significant implications for the search for life on other planets.
