Why did almost all multicellular organisms begin life as a single cell?

A good friend of Deskarati is writing a book describing the world as we know it and how it came to be. He has finished the first section from big bang to a time when Earth was first suitable to produce life. So as he begins to explain where we came from, Deskarati asks what might seem an obvious question – Why did almost all multicellular life begin as a single cell? – Deskarati –

Any multicellular animal, from a blue whale to a human being, poses a special difficulty for the theory of evolution. Most of the cells in its body will die without reproducing, and only a privileged few will pass their genes to the next generation. How could the extreme degree of cooperation multicellular existence requires ever evolve? Why aren’t all creatures unicellular individualists determined to pass on their own genes?

Joan Strassmann, PhD, and David Queller, PhD, a husband and wife team of evolutionary biologists at Washington University in St. Louis, provide an answer in the Dec. 16 issue of the journal Science. Experiments with amoebae that usually live as individuals but must also join with others to form multicellular bodies to complete their life cycles showed that cooperation depends on kinship. If amoebae occur in well-mixed cosmopolitan groups, then cheaters will always be able to thrive by freeloading on their cooperative neighbors. But if groups derive from a single cell, cheaters will usually occur in all-cheater groups and will have no cooperators to exploit.

The only exceptions are brand new cheater mutants in all-cooperator groups, and these could pose a problem if the mutation rate is high enough and there are many cells in the group to mutate. In fact, the scientists calculated just how many times amoebae that arose from a single cell can safely divide before cooperation degenerates into a free-for-all. The answer turns out to be 100 generations or more.

So population bottlenecks that kill off diversity and restart the population from a single cell are powerful stabilizers of cellular cooperation, the scientists conclude. In other words our liver, blood and bone cells help our eggs and sperm pass on their genes because we passed through a single-cell bottleneck at the moment of conception.

The social amoebae

Queller, the Spencer T. Olin professor, and Strassmann, professor of biology, moved to WUSTL from Rice University this summer, bringing a truckload of frozen spores with them. Although they worked for many years with wasps and stingless bees, Queller and Strassmann’s current “lab rat” is the social amoeba Dictyostelium discoideum, known as Dicty for short.

The social amoebae can be found almost everywhere; in Antarctica, in deserts, in the canopies of tropical forests, and in Forest Park, the urban park that adjoins Washington University. The amoebae spend most of their lives as tiny amorphous blobs of streaming protoplasm crawling through the soil looking for E. coli and other bacteria to eat.

Things become interesting when bacteria are scarce and the amoebae begin to starve. They then release chemicals that attract other amoebae, which follow this trail until they bump into one another. A mound of some 10,000 amoebae forms and then elongates into a slug a few millimeters long that crawls forward (but never backward) toward heat and light. The slug stops moving when it has reached a suitable place for dispersal, and then the front 20 percent of the amoebae die to produce a sturdy stalk that the remaining cells flow up and there become hardy spores. Crucially, the 20 percent of the amoebae in the stalk sacrifice their genes so that the other 80 percent can pass theirs on.

When Strassmann and Queller began to work with Dicty in 1998, one of the first things they discovered was that the amoebae sometimes cheat. Dennis Welker of Utah State University had given them a genetically diverse collection of wild-caught clones (genetically identical amoebae). They mixed amoebae from two clones together and then examined the fruiting bodies to see where the clones ended up. Each fruiting body included cells from both clones, but some clones contributed disproportionately to the spore body. They had cheated. How can a blob of protoplasm cheat? The answer, it turns out, is many different ways.

“They might,” Queller says, “have a mutation that makes an adhesion molecule less sticky, for example, so that they slide to the back of the slug, the part that forms spores.”

“But there are tradeoffs,” Strassmann says, “because if you’re too slippery, you’ll fall off the slug and lose all the advantages of being part of group.”

More here  Close family ties keep cheaters in check: Why almost all multicellular organisms begin life as a single cell.

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4 Responses to Why did almost all multicellular organisms begin life as a single cell?

  1. Geza says:

    If someone thinks I’m wrong feel free to write some.

    My understanding is that the single cell and multicellular organisms has no differences. Multicellular organisms is nothing but a first cell multiplied by their functional relationship in organism whom is belong. In religious concept the first cell of mankind were Adam and Eve, now all people, they are 7 bilions are amplified as singular Man – Eve and Adam.

    Bertrand Russell British mathematician and philosopher exploring
    definitions of number found that the number two we have never touch. Everything is just One such couple of Mr. and Mrs. Robinson, as Russell said.

    If you look mathematical universe of numbers then any number of the universe no matter how big or small is, always is the number One. All other numbers are only amplified of One.

    In our optical perception we have a One white “ color ” that when divide have four Complementary colors, which built all other colors and their shades no matter how many there are. Each of these has its own Complementary colors which united made first white One “color”.

    It’s the same with anything else! So you actually still have interaction of two units, two of the universe “- 1” and “+1”. These are two polar Units are inverse ti each to other starting in that way any universe, so the universe of th multicellular orgnism . This is the answer to the question: Why did almost all multicellulral organism begin life as a single cell? Anssver is: Becouse every multicellural organize consist of meny One singular Cels, or Units.

    A good example is the DNA molecule which always consists of four AGCT nucleotide no matter to which the organism is involved. This is purine – pyrimidine pair whish is always can be duplicated in a large number doing so multicellural organism

    Let’s try to think in that direction.

  2. Phil Krause says:

    What a fascinating explanation Geza! Not sure that I completely follow the argument but I suppose that you could also say that every word ever written in the English language starts from just 26 letters.

    However, I suspect that the real reason that all life starts from a single cell is that its the single cell that is the only real life. The first life that lived and still lives on the Earth are single celled prokaryotes; everything comes from them. First they gradually diversified occupying more and more environmental niches around the world, exploring ever more ways to exploit the available energy around them. The largest supply of energy comes from the sun and it couldn’t have been long before this source was tapped. A consequence of this type of metabolism was that oxygen was released as a waste product. Over one or two thousand million years this oxygen saturated the oxygen hungry elements on the surface of the earth and began to accumulate in our atmosphere and dissolve in the seas. At first, this would have been poisonous to life but over time life adapted, to not only withstand it but to thrive on it. Life’s metabolisms can obtain almost 20 times more energy from the same energy source when oxygen is available. Now much more is possible than before, the race begins.

    The earth was formed along with the rest of our solar system about 4.5 billion years ago. It wasn’t long before life got started in the sea from the basic organic building blocks that formed on the surface of the earth and had fallen to the earth from compounds on its accrued building blocks. It took only around 500 million years before the first life that we recognize started in the form of single celled prokaryotes. It took a further 3 billion years before the oxygen had built up enough for the offspring of some modified cells to work together as a family and begin multi celled life as we know it. Its only just over 500 million years since these cells formed the body shapes that still make up our animal and plant life of today. Although, these multi celled creatures have exploited new ways to reproduce they can still only do it by going right back to their single celled roots.

  3. Deskarati says:

    We found this interesting article discussing how multicellular life started and suggesting it might be descended from a parasitic invasion! – Deskarati –

    Eons ago, two single-celled organisms, a bacterium and an archaeon, combined to form the first complex cell. This symbiosis gave birth to all multi-cellular organisms, but new evidence suggests this wasn’t about cooperation. That bacterium was actually a parasite.

    Two billion years ago, an archaeon swallowed a bacterium, and for whatever reason it forgot to digest its meal. This was the birth of the eukaryotes, and now every last one of our cells act as a silent monument to this first complex cell that formed two billion years ago. In this symbiotic partnership, the archaeon developed into the cells of complex organisms, while the bacterium that it ingested became the mitochondria, the energy producing powerhouses found inside all our cells.

    But it seems the entire eurkaryotic domain might be built on a lie. Far from a moment of impromptu partnership, the first complex cell might actually have been the accidental byproduct of an attempted invasion by a parasitic bacterium. That’s the contention of researchers Nathan Lo at Australia’s University of Sydney and Claudio Bandi at Spain’s University of Valencia, who have done extensive genetic studies on the bacteria most closely related to our mitochondria, the Rickettsiales.

    Some of the bacteria within this group, including a species with the evocative name Midichloria mitochondrii, carry the genes necessary for a flagellum, a whip-like tail used by some bacteria to move about. The problem is that the “some bacteria” here are almost exclusively parasites. If the Rickettsiales are any indication, then the bacteria that became our mitochondria also carried flagella – and if that’s true, then odds are they were parasites.

    Of course, we’re talking at a remove of two billion years from that first complex cell, which is plenty of time for these Rickettsiales to pick up a flagellum elsewhere, particularly considering how readily bacteria share genetic information with each other. But the researchers reconstructed the evolutionary tree for the Rickettsiales, and it appears the truth is that once all these bacteria carried flagella, and most simply lost them in the last two billion years.

    That bolsters the argument for ancient parasitism, but there are still some unanswered questions. One possible objection is that a parasitic relationship is, by its nature, destructive to the host cell, and so it’s unlikely all complex cells could be descended from such a coupling. But Nathan Lo counters, “Many symbiotic relationships start as parasitism – they give up fighting each other and then work together.” If so, then we’re looking at two billion years of unbroken peace between parasite and host. That has to be some sort of record.

    Via io9.com

  4. Geza says:

    Phil, I am not talking about English language starts from just 26 letters. I am talking that every being on the Word in flora and fauna starts with four genome letters ATCG, or with complementary purine and piramidine pairs. Oll other DNA molecules are multiplication of these elementary four letters ( molecules ) in many, many combinations and permutations of what we call the genome.

    One can bi fascinated or not, but they should all be fascinated with the fact that everything is structurally polar, but not only with two poles, but with four poles .
    For example. Permanent magnet we perceive as a magnet with two poles, N – S and thereby always omit the middle of the magnet where also two half-micro pole of magnets in inverse departed. This means that we do not have a magnet with two poles, because fact is that we have magnet with four poles, two on the periphery of the polar maximum and two in the center as the polar minimum. Thus, the relation is not magnet N … .. S, because the fact is that the relation of magnets is N … … .. s / n … … ..S , which is significantly different from the usual perception of the magnet. First is linear, and the other is non linear perception.

    When I say four letter it does not means number four as four briks or four cars, it means four polar identity of One, as is, for example, four quarters of circle ABCD , what is make One total circle F. What is fascinating here? Fascinating is the fact that four letter name of Good JHWH with combination and permutation is writes the Jewish Bible, same as four biological letters ATCG writes all genomes for beings on the Word;

    Fascinating is that wit four elementary heksogram in Chinese Ji – Jin knowledge is writes full context of the Ji Jing table which presents all Universe phenomena. Fascinating is that Kurt Gödel create the basic mathematical tables with four term.
    fascinating is that Bach composed his music quaternary, as well as its famous Esher made his intelectual graphics, what is very well explained in Hofstader book GEB.
    End finally fascinating for me is the fact that all phenomena has four levels of living, like four levels of catapilar metamorfosis. Last fourth level is the level where occurs the totality of the beings and the new Origin of the same beings. On this four level of fife phenomenon occure to polar inflection and the inflection point as the new Origin. I have to explain that in article Pi Phenomenon, which is in Jim hands, where is explained a new concept of Pi, not as a number, but as information about the “ point “ of the Origin of totality which is consists of three whole and parts of the four whole as 3 + 0, 142= 3,14 as information about the inflection point. Inflection point or Origin is the border of totality for the every being. This is not my sensations, that is sensations of the logos and structure of the Origin. Origin sensation makes to human mind front of open door end a new space for new non-linear knowledge.

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