ANCESTOR OF LIFE

HERE did life come from? What could possibly be the first living, breathing, primordial ancestor of all beings on Earth?

- HRITHIK KIRAN BAGADE

The search for answers to such compelling questions leads to LUCA!

The Last Universal Common Ancestor, or LUCA, represents a foundational concept in evolutionary biology. It refers to the most recent common ancestor from which all current life on Earth descends. While LUCA is not exactly the first life form, it is the earliest organism for which we can trace a universal lineage connecting all domains of life: Bacteria, Archaea, and Eukarya. Studying LUCA is crucial for understanding the origin of life and the evolutionary processes that have shaped biodiversity over billions of years.

The idea of a universal common ancestor dates back to Charles Darwin, who in On the Origin of Species (1859), suggested that all life might share a common origin. Modern science has supported this hypothesis through molecular biology, particularly the universality of the genetic code. All known life uses DNA or RNA to encode genetic information, and proteins constructed from amino acids through ribosomes, indicating a shared evolutionary heritage. LUCA is therefore not a specific species or fossil, but a theoretical construct inferred from shared genetic and biochemical traits.

Scientists have attempted to reconstruct LUCA's characteristics using comparative genomics. By examining the genes common to all three domains of life, researchers can hypothesize what LUCA's genome may have contained. Studies suggest that LUCA likely lived around 3.5 to 4 billion years ago in an environment rich in hydrogen, possibly near hydrothermal vents in the deep ocean. These conditions would have provided both the chemical energy and the physical shelter required for early life to develop.