The origin of the very first species and the start of Darwinian evolution

November 23, 2015
At the root of the tree of life: The first biological species, which initiated Darwinian evolution, presumably originated in a collective state of mixed genomes lacking well-defined species. Credit: Jose Casadiego, Carolin Hoffrogge and Marc Timme

During the earliest evolution on earth, life probably resembled one big genetic jumble. At some time, presumably around 3.8 to 3.5 billion years before today, the very first biological species appeared – the ancestor of all life forms that developed via Darwinian evolution. Researchers at the Max Planck Institute for Dynamics and Self-Organization in Göttingen and at Cornell University in the USA have now conceived and modelled a possible scenario by which the first defined species could have emerged from this genetic mix. The researchers proposed that before the dawn of Darwinian evolution, life fluctuated back and forth between a genetically highly mixed and a partially unmixed state. Over time, the less mixed state exhibiting a more clearly defined genetic profile became increasingly stable and eventually generated the very first species.

Already in 1937, the tree of life sketched by Darwin illustrated his hypothesis of how existing species continually gave rise to new ones while other species die out. The resulting family tree since then became the guiding principle of evolutionary research in general, highlights the common origin of all as well as how they are related. The root of this genealogical tree is composed of one specific species of primordial unicellular organisms, which are the progenitors of all living beings that exist on earth today. Yet even before the emergence of this very first species, which passed on its genome from generation to generation, there was probably already life evolving on earth. "We were fascinated by the question how this first species originated and what triggered the transition to Darwinian evolution," says Marc Timme, Head of the research group on Network Dynamics at the Max Planck Institute for Dynamics and Self-Organization.

Today, some evolutionary researchers believe that the first biological species should already have possessed a relatively functional biochemical apparatus, and were relatively fit - in the Darwinian sense. Yet the components of life probably did not go together so well right from the start. Initially, life presumably existed in the form of a genetically highly mixed in which the biochemistry of individuals functioned in a very rough-and-ready fashion. It seems likely that even unrelated specimens of these early life forms promiscuously exchanged genetic material via during their lifetimes. In Darwinian evolution, however, the dominant form of inheritance from one generation to the next is vertical gene transfer, between generations.

The population's fitness increased sporadically

Thanks to this rampant exchange of genes in early evolution, it might have been possible that at different places within this strongly mixed state, individual biochemical instruments developed – instruments that were also useful for the unicellular organisms that made up the first defined species. It is conceivable that in some places even two or more of such instruments incidentally coincided. This would have increased the fitness of certain individuals, which then multiplied more rapidly and potentially also survived longer than the rest, causing their genetic code to aggregate and stand out from the otherwise randomly mixed collective of genes. It was in these organisms that the first signs of the emergence of a species sporadically began to appear.

Teaming up with Hinrich Arnoldt, who conducted research at the Max Planck Institute for Dynamics and Self-Organization, and Steven Strogatz, a scientist at Cornell University, Marc Timme has now presented a simple mathematical model showing that the collective state with highly mixed genetic material could have coexisted with the second, far less mixed state. Even at the beginning when the highly mixed state was predominant, the evolutionary dynamics repeatedly reverted into the less mixed state in which many cells shared similar genomes.

In the genetically unmixed state of greater biological fitness, the competence of to engage in horizontal gene exchange with other individuals would have decreased. That is because, due to their slightly more developed biochemical apparatus, it would have been more difficult for these cells to randomly incorporate the components imposed on them during the horizontal gene exchange. It is more likely that in genetically unmixed phases, the life forms instead passed on more or less unchanged versions of their genomes to daughter cells to following generations.

Increasing fitness: from a collective state to a distinct species

Initially, however, the genetically unmixed episodes did not last very long. Time and again the advantage for survival was lost in what was still a very undefined genetic blur. Horizontal gene transfer once again took over the reins – but no longer to the same extent. A trace of the superior biological fitness remained in some individuals within the collective state. This also meant that, on average, the collective state was hampered in its efforts to exchange genes horizontally and became a bit more biologically fit.

The model proposed by the German-American research team shows that over time the declining average ability to exchange genes horizontally caused the population to remain less frequently in the highly mixed state, and more often in the less mixed state. This could have gradually accelerated the development of evolution, which ultimately led to the emergence of the first biological species: As the population's fitness increased, its ability to transfer genes horizontally decreased, causing the collective to switch into less mixed states more frequently and for longer periods of time, which in turn further raised the fitness levels of a part of the population, and thus also the average population.

The researchers' most significant finding indicates a qualitative transition that put an end to the back and forth between highly mixed and unmixed states: Once the life forms were limited in their ability to exchange genes horizontally, the less mixed state not only became more common; it was adopted permanently, as the highly mixed state no longer existed. "Strongly related cells with similar genomes would then have persisted," says Steven Strogatz. That means: A primordial species could have formed because the combined biochemical configuration of a part of the population potentially functioned so well that these cells became more viable than the rest; their genomes were transferred to new generations via vertical gene transfer. As a result, the genetic blueprint of these cells permanently stood out from the rest of the collective: The first defined had emerged and paved the way for Darwinian evolution.

Explore further: Darwin's Tree of Life May Be More Like a Thicket

More information: Hinrich Arnoldt et al. Toward the Darwinian transition: Switching between distributed and speciated states in a simple model of early life, Physical Review E (2015). DOI: 10.1103/PhysRevE.92.052909

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Torbjorn_Larsson_OM
5 / 5 (4) Nov 23, 2015
Here is the free arxiv version to PhysRevE.92.052909: http://arxiv.org/...01.05073 .

It is simple for soup theory to propose HGT, but modern HGT is complex and it is not a natural state of early cells in vent theory who started out as inorganic pores before they acquired membranes. There is no compelling reason to think rampant HGT ever happened.

[The paper proposes a reason, universality, with a reference http://guava.phys...2009.pdf that in turns take it from http://www.pnas.o...full.pdf . But extinction would provide that too, and there are many other universal traits of the UCA lineage that is explained by that but not by early HGT.]

Read more at: http://phys.org/n...html#jCp
DrInAfrica
1 / 5 (5) Nov 24, 2015
Isn't it a bit presumptions to write an article that contains mainly probably and possibly statements with no scientific backing? Wouldn't it probably be better to assume a neatly formed species simply emerged?
Vietvet
3.9 / 5 (7) Nov 24, 2015
The science behind the hypothesis is here:
http://journals.a...2.052909
DrInAfrica
1 / 5 (5) Nov 24, 2015
Hi Vietvet - I have checked your recommended site and it is a set of science articles, not particularly related to this topic. I rather fear that, sometimes, when scientists need to prove a point, they do not necessarily apply rigorous science to their propositions.
Steelwolf
1 / 5 (1) Nov 27, 2015
It would be relatively easy for the horizontal transfer of genetics in such archea with no cell walls, so I can easily see how this applies. What I would question though is whether it would have precipitated a single 'primary' life form, or if it would have produced at least a pair of types, one that was able to feed on the other, and one that fed on the primordial soup direct, perhaps with one raiding another for the type of waste products that were It's primary foods. A pair like that, eventually to become mitochndria and nucleus of the overall, much later Cell, along with bits and pieces of other chemical experiments that it just happened to pick up via genetic exchange.

In the changing conditions on the planet, survival would be best for those organisms with the largest 'libraries' of odd genetic codes that it can Try for any set of problems, most dying, but the odd one surviving, and more importantly, propagating under the new or different condition.
antialias_physorg
5 / 5 (6) Nov 27, 2015
Isn't it a bit presumptions to write an article that contains mainly probably and possibly statements with no scientific backing? Wouldn't it probably be better to assume a neatly formed species simply emerged?

Since that is neither possible nor probable: no.
Vietvet
4.4 / 5 (7) Nov 27, 2015
Hi Vietvet - I have checked your recommended site and it is a set of science articles, not particularly related to this topic. I rather fear that, sometimes, when scientists need to prove a point, they do not necessarily apply rigorous science to their propositions.


Go to the link and click the portrait of Einstein. That will take you to:
"Toward the Darwinian transition:
Switching between distributed and speciated states in a simple model of early life"
chapprg1
not rated yet Nov 27, 2015
What is to prevent the occurrence and our observation of such "a genetically highly mixed and a partially unmixed state" in the present? If it occurred spontaneously, why not now?
BONK__RS
5 / 5 (3) Nov 27, 2015
why not now?
because all the biological niches are now filled with "fit" organisms, there is no more free lunch. If such a wild state were to arise again it would not gain a foothold and we would not see it.
SuperThunder
not rated yet Nov 27, 2015
Tardigrades have a lot of horizontally transferred genes, apparently. Of course, they're a lot more advanced than omnisoup (who I can't help but want to call Jehovah, probably because of Final Fantasy), and came later.
Torbjorn_Larsson_OM
5 / 5 (4) Nov 27, 2015
@Steelwolf:
- Archaea is at least a sister clade to bacteria, and - arguably - by deep rRNA sequencing have bacteria as stem clade. [Petrov et al, PNAS 2014 IIRC].
- Already RNA/protein cells of the UCA lineage had cell membranes, because the generic transporter tag for membrane proteins is RNA based.
- Mitochondria is an alphaproteobacteria, and the common cited date is that they evolved after an endosymbiosis about 2 billion years ago, after half the Earth history.

@SuperThunder: On average every gene has done 1 HGT/4 billion years. So that tardigrades do 20 % in ~ 0.5 billion years is good for an eukaryote but not as good as early on (when HGT seems to have been higher).
Freethinker51
1 / 5 (7) Nov 27, 2015
The most impressive organisms not mentioned by today's "bought" pseudo-scientists are cyanobacteria. These photosynthetic marvels ALONE turned earth's early poisonous atmosphere into what it is today. They paved the way for plant life. And then came more complex life forms.

The ability of this photosynthetic organism to dramatically change the earth's early atmosphere without the aid of plants reveals how powerful an influence they had and can still have. The good news is this: Even if we destroy most of our rain forests and pump loads of CO2 into the atmosphere, this organism ALONE can handle it and keep our atmosphere in balance. Doing so is a far easier task than taming a poisonous atmosphere. More CO2 means more cyanobacteria, means more oxygen, means more interaction with excessive methane. Every educated, HONEST climatologist should know this. Why the silence? Are they all in the pockets of corrupt politicians?
SuperThunder
5 / 5 (6) Nov 27, 2015
Freethinker is right, screw responsibility and the environment, this toxic algae will save us! We don't need a food chain, we just need cyanotoxins.

http://www2.epa.g...habs.pdf

Every educated, HONEST climatologist should know this. Why the silence? Are they all in the pockets of corrupt politicians?

No, they're just not idiots and they know your idea is stupid and uninformed, and probably paid for by a psychopath in HR of some corporation that wont exist in a civilized world.
RealityCheck
2.6 / 5 (5) Nov 27, 2015
Hi Freethinker51. :)

What you say is true, and reflects well on your study re cyanobacteria, its early action to produce all the oxygen which made oxygen-using life possible. :)

However, the cyanobacteria could do what you said because, back then, the seas/oceans/lakes etc were SATURATED with dissolved IRON/other necessary nutrients/micro-nutrients! They cannot do same to same scale NOW.

Consider: After some time, most DISSOLVED IRON previously in the water became OXIDIZED by the Oxygen cyanobacteria produced en masse, thus making vast majority INSOLUBLE; so it SETTLED OUT to form BOTTOM sediments layers (that's how/why our vast IRON ORE deposits arose).

Dissolved IRON in water PLUMMETED to relatively MINISCULE concentrations of today's equilibrium of global biologic-IRON cycle. There've been plans/attempts to 'fertilize' oceans with IRON, but so far (except for my proposed method) they all fail for a very specific reason (which I'm not at liberty to divulge yet).

Ok? :)
FainAvis
not rated yet Nov 28, 2015
Horizontal gene transfer could be achieved by hybridisation and backcrossing to stability, just as McCarthy has proposed.
viko_mx
1 / 5 (6) Nov 28, 2015
The basic functions of the living organisms are metabolism, the ability to multiply and leave next generation and self defense mechanisms, for which is needed complex structure and functionality that mast exist from the very beginning of their existence.
Complex need and purpose set requirement for complex functionality.
Random gradual events can not create such structure and functionality. They have no purpose, do not know the goal and the technology to achieve goal.

this is the reason why the most simple living organism found by scientists in external environment, have 1.2 million base pairs in its DNA.
RealityCheck
1 / 5 (1) Nov 28, 2015
Hi viko_mx. :)

Your argument works against your 'conclusions' that those things...
...must exist at the very beginning of their existence.
Consider: The fact that some natural reactions/developments DON'T succeed and so never become 'life' molecules/cells/organisms etc, means that those things you asserted become moot from the start. Since only when something succeeded in having naturally acquired/evolved those things did 'metabolism', 'survivability' 'multipy' etc become things that determine 'life'. Until that occurred, there was NO natural existence of such 'things'.

See? Such 'things' become 'real' and 'characteristic' of life processes/procreation ONLY AFTER there was 'life' etc to give those 'things' meaning/functionality/potential for evolution/complexity.

So, mate, postulating/demanding those 'things' before 'life' itself arose is, as it were, putting the 'supernatural god cart' before the 'natural a-biogenesis horse'!

Lose 'god cart'; keep 'real horse'. :)
AGreatWhopper
5 / 5 (3) Nov 28, 2015
Why is it that people that crow about "free thinking" are always the biggest parrots? Pitiful.
viko_mx
1 / 5 (5) Nov 29, 2015
@RealityCheck

Уour thoughts are very confused. Avoid to comment after alcohol use.

viko_mx
1 / 5 (5) Nov 29, 2015

Are you able to realize that any complex machine needs a certain number of parts to be able to function? Have you heard for irreducible complexity? Or have to stick to the political line?
This minimum number of parts increases with increasing of complexity of its functionality in a nonlinear law.
In the hypothetical first living organisms these parts are too much because the basic functionality of the cell requires a complex interconnected information from the outset. In nature things are optimized but there is no bacteria that live in the external environment with genome shorter than 1.2 million base pairs. Obviously this is the minimum complexity and information that can ensure the basic functions of bacteria.

Only the flagella of bacteria is consisted of more than 40 parts fitted perfectly to each other and this organelle is art work of engineering thought.
viko_mx
1 / 5 (5) Nov 29, 2015
The assembly of this organelle is also the complex process. But there is sense of its existence only if it is fully functional which applies also to every other organelle or organ in the living organisms.
RealityCheck
3.7 / 5 (3) Nov 29, 2015
Hi viko_mx. :)
@RealityCheck, your thoughts are very confused. Avoid to comment after alcohol use.

Hehehe. I can't drink, smoke, drug etc because of chronic health problems related to/consequences of damage done by a range of allergies since childhood. :)

In reply to your latest assertions re science aspects, I ask: Were YOU aware of chaotic, naturally self-organizing, reactions in chemistry, bio-chemistry and physics? These have simple quanta/units of energy-space and higher evolved energy-space features, which naturally interact to form 'lest energy' stable states at 'stability nodes' along the trajectory of states, from simplest to most highly evolved/complex. Hence the laboratory-observed/proven natural tendency of such systems go from amorphous simple/disorganized states, to ever-increasing complexity of states and phenomenological dynamics....which is what we observe all round us if one only takes a close scientific look at it without "religious" eyes. Ok? :)
jsdarkdestruction
5 / 5 (3) Nov 29, 2015
@RealityCheck

Уour thoughts are very confused. Avoid to comment after alcohol use.


One of the few accurate things you've said that was actually intentional.

Just a heads up viko, you are not much better than he is.
RealityCheck
1 / 5 (3) Nov 30, 2015
Hi jsdarkdestruction. :)

Hehehe. Mate, you're working from outdated/misinformed dataset regarding me. You obviously haven't been paying attention over the years, and especially since early last year. I am proven correct and all the troll claims to the contrary proven wrong. So if you don't want to further embarrass yourself as an uniformed irrelevance, drop the personal stuff, especially if you are wrong about someone. Thanks in advance for your better contribution to the objective science and humanity discourse in future, mate! :)
Whydening Gyre
5 / 5 (3) Dec 01, 2015
...There've been plans/attempts to 'fertilize' oceans with IRON, but so far (except for my proposed method) they all fail for a very specific reason (which I'm not at liberty to divulge yet).

Ok? :)

I guess THAT proposal is ALSO in your "up-coming" TOE...
RealityCheck
1 / 5 (3) Dec 01, 2015
Hi Whyde. :)

No, mate, it should appear before the ToE, since I have had to put the ToE finalizing/publishing on the back burner while I resume/complete urgent work on my Climate Change/CO2 solutions which were in the pipeline but have now become a matter of more urgency since my govt, especially previous PM Abbott, denied, sabotaged and generally set back the cause/effort for timely climate/renewables action progress; such that it is now more imperative and immediate cause of concern/concentration for me.

Wish me luck, for everyone's sake. :)
Whydening Gyre
5 / 5 (3) Dec 01, 2015
Hi Whyde. :)

No, mate, it should appear before the ToE, since I have had to put the ToE finalizing/publishing on the back burner while I resume/complete urgent work on my Climate Change/CO2 solutions which were in the pipeline but have now become a matter of more urgency since my govt, especially previous PM Abbott, denied, sabotaged and generally set back the cause/effort for timely climate/renewables action progress; such that it is now more imperative and immediate cause of concern/concentration for me.

Wish me luck, for everyone's sake. :)

Man, you're so BUSY.... I don't know how ya do it all...
RealityCheck
1 / 5 (4) Dec 01, 2015
Hi Whyde, :)

Many people just like to watch. Many people just like to watch and to heckle. Many people just like to watch and heckle and sabotage. And then there are those very few determined/constructive/creative people who just get on with doing it for its own sake and for the sake of their fellow human beings...and for the sake of their own curiosity/legacy motivations driving them to not waste too badly the time they have been fortunate enough to be given by chance and good fortune on this planet. It takes all kinds to make a world, mate....even artists, hey! Cheers. :)
Torbjorn_Larsson_OM
5 / 5 (4) Dec 01, 2015
Creationist crank: "needed complex structure and functionality that mast [sic] exist from the very beginning of their existence."

There is no such 'must', which is why there is no reference given to any science result. On the contrary, evolution show us that *all* functionality has been fixated by evolutionary mechanisms. In effect the pared down complexity of the genome, ordered bases instead of unordered bases as per creationist complexity ideas, is learned from the environment and channeled as Shannon information into the genome. There are many studies of that easily observed process.

Now that creationism has been tested as erroneous, as per the creationists own suggested test, will they stop trolling inanities on science sites? No doubt they won't: as opposed to genomes *they* are not functional enough to learn from the environment and achieve a modicum of complexity.
Torbjorn_Larsson_OM
4.8 / 5 (4) Dec 01, 2015
Creationist crank: "Are you able to realize that any complex machine needs a certain number of parts to be able to function?"

Are you able to realize that criterion is self fulfilling?

In the reality where the rest of us live, a hammer is fulfilling a complex function, yet it is one mechanical piece. Similarly a replicator is fulfilling a complex function, yet the original one was one chemical molecule.

And stop spouting religious terms like 'irreducible complexity' around on a science site! No one is interested in your erroneous theology.
Captain Stumpy
5 / 5 (3) Dec 05, 2015
And then there are those ...who just get on with doing it for its own sake and for the sake of their fellow human beings...
@sam-U-am
except that you said you would be at the climate change conference this year...(edited for space)
I am trying to get my solutions into 'presentation' shape in time for the next major International Climate Change Conference sometime this year...this GW solutions project has now become too urgent for me to leave it on the backburner any longer in all good conscience. Hang in there, guys! In both cases. The Reality-cavalry is coming to the rescue...
http://phys.org/n...fic.html

considering you were at exactly ZERO climate change conferences presenting this year, and you didn't publish anything (not even to your earthlings) then the conclusions can only be that you are full of bs and delusional, like any religious fanatic

except they can reference something published, unlike you
RealityCheck
1 / 5 (2) Dec 06, 2015
Hi CapS. :)

Patience, grasshopper. :)

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