Research Suggests all Humans Share One Single Ancestor—and it’s not Adam

Diversity is often hailed as the essence of beauty—an observation that is readily apparent when we consider the vibrant array of flowers, animals, landscapes, and humans that populate our world.

Contrary to popular beliefs—like those found in biblical texts—the progenitor of all living organisms wasn’t named God or Adam but is known as LUCA.

Modern life evolved from LUCA from various sources. These sources include amino acids used to build proteins in all cellular organisms, the shared energy currency, the presence of cellular machinery, and DNA’s purpose of storing information.

This tiny, rudimentary life form is considered the root of the entire tree of life, encompassing everything from the tiniest bacteria to the most massive creatures that have ever existed.

For a long time, scientists estimated that LUCA emerged approximately 4 billion years ago—around 600 million years after the Earth was formed.

Scientist Edmund Moody and his colleagues from the University of Bristol compared all the genes in the genomes of living species in a new study, counting the mutations that have occurred in their sequences over time.

“The evolutionary history of genes is complicated by their exchange between lineages,” Dr. Moody said. “We have to use complex evolutionary models to reconcile the evolutionary history of genes with the genealogy of species.”

By remodeling the physiological characteristics of modern living species, the study’s authors were able to work out the biology of LUCA.

To achieve this, they employed a technique that involved analyzing genetic data from modern species and tracking the mutations that have accumulated since these species diverged from their common ancestor—LUCA.

“Our study showed that LUCA was a complex organism, not too different from modern prokaryotes,” said University of Bristol’s Professor Davide Pisani. Prokaryotes are microscopic single-celled organisms that do not have a distinct nucleus with a membrane or specialized organelles.

This new timeframe places LUCA squarely within the Hadean Eon, a tumultuous period named after Hades, the Greek god of the underworld.

The fact that LUCA managed to survive in such a harsh environment is remarkable.

Their investigation revealed that, despite LUCA’s simplicity as a prokaryote—a single-celled organism lacking a nucleus and membrane-bound organelles—it likely possessed a primitive immune system.

Tim Lenton, a co-author of the study from the University of Exeter, noted, “It’s clear that LUCA was exploiting and changing its environment, but it is unlikely to have lived alone.”

“It’s clear that LUCA was exploiting and changing its environment, but it is unlikely to have lived alone,” said Dr. Tim Lenton, a researcher at the University of Exeter.

Although LUCA remains the oldest known common ancestor, the path from this primordial life form to the complex organisms we see today is still a subject of ongoing research.

Further exploration is needed to fully understand how life evolved from its earliest beginnings.

The research not only pushes back the timeline of LUCA’s existence but also provides fascinating insights into its characteristics and the conditions of early Earth.

“The findings and methods employed in this work will also inform future studies that look in more detail into the subsequent evolution of prokaryotes in light of Earth history, including the lesser studied Archaea with their methanogenic representatives,” said Professor Anja Spang, a researcher at the Royal Netherlands Institute for Sea Research.

“Our work draws together data and methods from multiple disciplines, revealing insights into early Earth and life that could not be achieved by any one discipline alone,” said University of Bristol’s Professor Philip Donoghue.

Currently, ten planets could closely resemble Earth, supporting life like LUCA and eventually a future species like humans.

One planet that could potentially support life like LUCA is 22 light-years from Earth and is at least 4.5 times as massive as Earth, according to NASA’s Jet Propulsion Laboratory.

Kepler-22b is located 600 light-years away and is considerably larger than Earth. Dubbed the “super-Earth,” it is unclear if the planet is rocky, liquid, or gaseous.

Located about 2,700 light-years away, Kepler-69c, which is 70 percent larger than Earth, is located in a habitable zone, but researchers are unsure about its composition.