LUCA - the mega-organism which spawned all life on Earth?

[SpaceMarine93]

From the Daily Mail:

Beginning of life: Scientists believe that the ocean was turned into a global mega-organism 3 billion years ago before giving birth to the ancestors of all living things today

The ocean was turned into a global mega-organism 3 billion years ago before giving birth to the ancestors of all living things today, research has revealed.

Scientists are currently attempting to confirm the last universal common ancestor - the life form that gave rise to all others.
This single organism has been called LUCA and is now traceable in all domains of life including plants, animals and fungi.

According to the latest research, which has been published in New Scientist, LUCA was an enormous 'mega-organism' which filled the planet's oceans before splitting into three and giving birth to the ancestors of all living things today.
It was the result of early life's fight to survive which turned the ocean into a 'global genetic swap shop' for hundreds of millions of years.

Cells struggling to survive on their own exchanged useful parts with each other without competition, creating the 'mega-organism'.
Scientists believe that it was about 2.9billion years ago when LUCA split into the three domains of life - bacteria, archaea and eukaryotes.

But little is known about what happened before the split.
Research into this area is being carried out by Gustavo Caetano-Anolles of the University of Illinois.

Speaking to New Scientist, he says early cells must have shared their genes and proteins with each other in order to survive.
Molecules which were new and useful would have been passed between cells without competition and gone global.

He said: 'It was more important to keep the living system in place than to compete with other systems.'
This free exchange and lack of competition meant that the ocean functioned as the 'single mega-organism'.
The mega-organism was only broken apart when some of the cells evolved ways of producing everything they needed.
Once this happened, Earth changed forever and all living things of today were born.

This is fascinating. So there is evidence suggesting that there is indeed one common ancestor to all life, a primordial, primitive planet-spanning being, like the Ocean from the Sci-Fi novel Solaris by Stainlaw Lem. And it is from which all life descended from. Just think of the implications...

[Lord Zentei]

Link.

So, the early forms of life were commies and developed capitalism later.

[Akhlut]

Scientists believe that it was about 2.9billion years ago when LUCA split into the three domains of life - bacteria, archaea and eukaryotes.

If I'm reading this correctly, this makes some papers I've read for my phylogeny class make a whole lot more sense; if that split occurred, more or less, simultaneously, it would explain why some groups of Archaea are more related to Eukarya rather than the rest of Archaea.

This is fascinating. So there is evidence suggesting that there is indeed one common ancestor to all life, a primordial, primitive planet-spanning being, like the Ocean from the Sci-Fi novel Solaris by Stainlaw Lem. And it is from which all life descended from. Just think of the implications...

The idea that all current life has one common ancestor isn't really news to biologists; it's been the working assumption for the better part of a century, at least.

This particular idea is a bit odd, and might be useful for searching for extraterrestrial sources of life, and might have some implications on searching for how life began via lab experiments, but otherwise I don't see much use for current biology outside of new Miller-Urey sorts of experiments.

It is fairly interesting and cool news, though. Hope more work is done on it in the near future.

[KhorneFlakes]

Looked like bull at first, going from the title, but had a look, and I'll admit: This is very interesting.

[Darth Holbytlan]

Here is the full article.

The proteomic complexity and rise of the primordial ancestor of diversified life.
Kim KM, Caetano-Anollés G.

Evolutionary Bioinformatics Laboratory, Department of Crop Science, University of Illinois, Urbana, USA.
Abstract
BACKGROUND: The last universal common ancestor represents the primordial cellular organism from which diversified life was derived. This urancestor accumulated genetic information before the rise of organismal lineages and is considered to be either a simple 'progenote' organism with a rudimentary translational apparatus or a more complex 'cenancestor' with almost all essential biological processes. Recent comparative genomic studies support the latter model and propose that the urancestor was similar to modern organisms in terms of gene content. However, most of these studies were based on molecular sequences, which are fast evolving and of limited value for deep evolutionary explorations.

RESULTS: Here we engage in a phylogenomic study of protein domain structure in the proteomes of 420 free-living fully sequenced organisms. Domains were defined at the highly conserved fold superfamily (FSF) level of structural classification and an iterative phylogenomic approach was used to reconstruct max_set and min_set FSF repertoires as upper and lower bounds of the urancestral proteome. While the functional make up of the urancestral sets was complex, they represent only 5-11% of the 1,420 FSFs of extant proteomes and their make up and reuse was at least 5 and 3 times smaller than proteomes of free-living organisms, repectively. Trees of proteomes reconstructed directly from FSFs or from molecular functions, which included the max_set and min_set as articial taxa, showed that urancestors were always placed at their base and rooted the tree of life in Archaea. Finally, a molecular clock of FSFs suggests the min_set reflects urancestral genetic make up more reliably and confirms diversified life emerged about 2.9 billion years ago during the start of planet oxygenation.

CONCLUSIONS: The minimum urancestral FSF set reveals the urancestor had advanced metabolic capabilities, was especially rich in nucleotide metabolism enzymes, had pathways for the biosynthesis of membrane sn1,2 glycerol ester and ether lipids, and had crucial elements of translation, including a primordial ribosome with protein synthesis capabilities. It lacked however fundamental functions, including transcription, processes for extracellular communication, and enzymes for deoxyribonucleotide synthesis. Proteomic history reveals the urancestor is closer to a simple progenote organism but harbors a rather complex set of modern molecular functions.

Perhaps one of our resident biologists can interpret.

[Tasoth]

From what I can gather, this urancestor was a huge colony of prokaryote like cells that swapped genes to make specific parts that were needed to functions and not all cells had all the genes to meet all the functions they needed. I am picturing this as a giant biofilm of microscopic Mr/Mrs.Potatoheads that are constantly swapping parts to try and make a complete Mr/Mrs.Potatohead and that these Potatohead organisms were too busy trying to survive to compete amongst one another. What changed is one of these cells, most likely several different ones, developed the ability to meet all their demands without relying on others and took off.

[Starglider]

I am picturing this as a giant biofilm of microscopic Mr/Mrs.Potatoheads that are constantly swapping parts to try and make a complete Mr/Mrs.Potatohead and that these Potatohead organisms were too busy trying to survive to compete amongst one another.

Competition is intrinsic to self-replicating systems in a resource-constrained environment. In biology competition is fundamentally at the gene level, it's just that with complex highly differentiated multicellular life genes are bundled into huge chromasomes which are mostly shared across populations of giant colonies (individuals of species), so we can reasonably simplify to competing organisms and species. In an environment where species don't exist and the concepts of chromasome, phenotype and individual aren't yet meaningful, loose federations of genes will still be competing like crazy, it just won't be as obvious. Or as efficient; things like sexual reproduction evolved to more efficiently turn competitive pressure into phenotype optimisation.