A groundbreaking study has revised the timeline for the Last Universal Common Ancestor (LUCA) of all life on Earth, placing its existence around 4.2 billion years ago - much closer to the planet’s formation than previously estimated.
This new estimate comes from research recently published in Nature Ecology & Evolution.
LUCA, while not the first life form, is considered the common ancestor of all living organisms.
Prior fossil evidence has traced life back to approximately 3.4 billion years ago, but this study suggests that LUCA might have emerged nearly simultaneously with Earth's formation. This implies that fundamental biological processes such as the genetic code and DNA replication may have developed very early in Earth's history.
The research team analyzed 700 genomes from bacteria, archaea, and fungi, constructing a model of LUCA’s genome. Notably, eukaryotes like plants and animals were excluded as they evolved later.
The study identified 57 gene families integral to understanding the evolutionary connections among these organisms.
According to the findings, LUCA was a complex organism akin to modern bacteria or archaea, but it lacked the ability to perform photosynthesis. The study introduced a novel method to estimate LUCA’s age using paralogous genes and fossil records, addressing the challenge of limited direct fossil evidence from Earth's early years.
This reconstruction of LUCA marks a significant leap in our understanding of early life on Earth. However, the study acknowledges that these conclusions may evolve with future discoveries and technological advancements, potentially offering deeper insights into the origins of life.