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Stay Hungry. Stay Foolish.

A blog by Leon Oudejans

LUCA, our Last Universal Common Ancestor (2)

The article below makes me wonder if I should reconsider my complexity vs simplicity blogs. The default in life, nature and the universe appears to be complexity. Moreover, it also suggest there’s a blueprint in life, nature and the universe. Also see my 2025 blog: Is a Universal design likely?

Obviously, an organism with an “early immune system” that was “fighting off viruses” implies consciousness apart from complexity.

I expect that LUCA will – once – be related to extraterrestrial viruses. This idea relates to the scientific field of astrobiology (eg, Wiki), also known as panspermia (eg, Wiki). Astronomer Fred Hoyle (1915-2001) had noticed a link between pandemics and meteorites (eg, Discover, Guardian, Harvard).

Obviously, it would be highly unlikely – and probably even impossible – that extraterrestrial viruses would only bring life to planet Earth. Hence, complex and conscious life is – probably – the default throughout the Universe.

In my view, sightings of UFOs are evidence of that conclusion. Wiki: “While unusual sightings in the sky have been reported since at least the 3rd century BC, UFOs became culturally prominent after World War II [] “. Note LO: bold markings by me.

Moreover, the Sumerian King List opens with this line:

After the kingship descended from heaven, the kingship was in Eridu.

It’s relevant – at least to me – that Abraham, Moses, Jesus, and also Muhammad are all related to that Sumerian civilisation.

Please also see my comparison between politics, religion, and the Sumerian King List in my 2018 blog: The Sumerian King List and Genesis.

In my 2022 blog Ancient origins, I made a timeline featuring various of the above topics:

Source: my 2022 blog Ancient origins

Earth is approximately 4.5 billion years old, with the first microbial life forms appearing over 4 billion years ago.

Phys-2025: Complex life developed nearly 1 billion years earlier than previously thought, study reveals

Luka (1987) by Suzanne Vega
artistlyricsvideoWiki-artistWiki-song

[Verse 1]
My name is Luka
I live on the second floor
I live upstairs from you
Yes, I think you’ve seen me before

Note: all markings (bolditalicunderlining) by LO unless in quotes or stated otherwise


All Life on Earth Comes From One Single Ancestor. And It’s So Much Older Than We Thought. (Popular Mechanics)

PM subtitle: Scientists have pushed back LUCA’s origin by hundreds of millions of years.

By: Darren Orf
Date: 15 December 2025

“Here’s what you’ll learn when you read this story:

  • All life on Earth can be traced back to a Last Universal Common Ancestor, or LUCA.
  • A study suggests that this organism likely lived on Earth only 400 million years after its formation.
  • Further analysis also shows that this life form likely sported an early immune system, which means it was probably fighting off viruses.

Life on Earth had to begin somewhere, and scientists think that “somewhere” is LUCA—or the Last Universal Common Ancestor. True to its name, this prokaryote-like organism represents the ancestor of every living thing, from the tiniest of bacteria to the grandest of blue whales.

While the Cambrian Explosion kickstarted complex life in a major way some 530 million years, the true timeline of life on Earth is much longer. For years, scientists have estimated that LUCA likely arrived on the scene some 4 billion years, which is only 600 million years after the planet’s formation.

But a study from an international team of scientists pushes that timeline back even further to some 4.2 billion years ago, while also discovering some fascinating details about what life for LUCA might’ve been like. The results of the study were published in the journal Nature Ecology & Evolution.

To zero in on exactly when LUCA appeared on Earth, scientists had to work backward. First, the team compared genes in living species and counted the mutations that have occurred since sharing a common ancestor with LUCA. Using a genetic equation based on the time of separation between species, the team worked out that LUCA must’ve been mucking around on Earth as early as 400 million years after its creation, which puts this organism smack in the middle of the hellish geologic nightmare known as the Hadean Eon.

“The evolutionary history of genes is complicated by their exchange between lineages,” University of Bristol’s Edmund Moody, the lead author of the study, said in a press statement. “We have to use complex evolutionary models to reconcile the evolutionary history of genes with the genealogy of species.”

Not satisfied with just learning its age, the team took things a step further and retraced the physiological characteristics of living species to understand what LUCA must’ve been like 4.2 billion years ago—and the results gave some surprising answers. The scientists estimate that while LUCA was a simple prokaryote, it likely had an immune system, meaning it was already fighting off primordial viruses.

“It’s clear that LUCA was exploiting and changing its environment, but it is unlikely to have lived alone,” University of Exeter’s Tim Lenton, a co-author of the study, said in a press statement. “Its waste would have been food for other microbes, like methanogens, that would have helped to create a recycling ecosystem.”

While LUCA is the oldest common ancestor we know of, scientists still don’t understand how life evolved from its very origins to the early communities of which LUCA is a part. Further studies will need to dive deeper into this primordial history and uncover exactly how you, me, and every other living thing, came to be.”


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