From Simple To Complex

By Jef Akst From Simple To Complex The switch from single-celled organisms to ones made up of many cells has evolved independently more than two dozen times. What can this transition teach us about the origin of complex organisms such as animals and plants?

By | January 1, 2011

From Simple To Complex

The switch from single-celled organisms to ones made up
of many cells has evolved independently more than two dozen times. What can this transition teach us about the origin of complex organisms such as animals and plants?

Sean McCabe

Given the complexity of most organisms—sophisticated embryogenesis, differentiation of multiple tissue types, intricate coordination among millions of cells—the emergence of multicellularity was ostensibly a major evolutionary leap. Indeed, most biologists consider it one of the most significant transitions in the evolutionary history of Earth’s inhabitants. But single-celled organisms have stuck together or assembled to spawn multicellular descendants more than two dozen times, suggesting that maybe it’s not such a big leap after all.

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1 “These genes that we previously thought were associated with complex multicellular animals really have to do with basic multicellular functions—to get the simplest multicellular animals, you have to have these genes present,” says Srivastava, who coauthored the analysis.

As some of the most ancient animals, sponges can provide information regarding the evolution of the metazoan lineage, but for true insights about the origin of multicellularity, scientists must look even further back on the evolutionary tree. Choanoflagellates, unicellular organisms that look remarkably similar to the feeding structures of sponges, are the closest living relatives of metazoans. It turns out that they also share a number of genes once thought to be unique to multicellular animals. Tyrosine kinases (TK), for example, enzymes that function in cell-cell interactions and regulation of development in animals, were identified in the choanoflagellates in the early part of this decade, and the first sequenced choanoflagellate genome, published in 2008, revealed that they have more TK genes than any animal—and many other components of the TK signaling pathway as well.2

“So this gene family that was thought to be essentially a trigger that unleashed animal origins, we can now say with great confidence evolved long before the origin of animals,” says evolutionary biologist Nicole King of the University of California, Berkeley, who has been studying choanoflagellate biology for over 10 years.

Scientists have also identified choanoflagellate homologs of cadherins, known to be involved in cell-cell adhesion and signaling in animals. And more recently, a widespread search for genes associated with integrin-mediated adhesion and signaling pathways revealed that the integrin adhesion complex originated much earlier than even the choanoflagellates, dating back to the common ancestor of animals and fungi.3

“It’s pretty surprising to find these adhesion genes in far-flung species,” says Srivastava. “We would have thought that integrin signaling has to do with cells sticking together, but it goes much further back in time than our most recent unicellular cousins.”

The genomic exploration of the evolution of multicellularity is really just beginning, but already, a trend is emerging. “Almost every month now we are seeing genes that were supposed to be exclusive to metazoans that are already present in their single-cell relatives,” says evolutionary biologist Iñaki Ruiz-Trillo of the University of Barcelona. “I think that means co-option of ancestral genes into new functions is important for evolutionary innovations like the origin of multicellularity.”

“Probably the more data we collect, the fewer and fewer animal-specific genes there are going to be,” agrees Dunn. “And we’re going to have to explain the origins of multicellularity in terms of changes in the way these gene products interact with each other.”

We tend to think of [the evolution of multicellularity] as quite special, but maybe it’s not. Maybe this is an easier transition than we think.
—Casey Dunn, Brown University

Unfortunately, because the genomics data are so new, experimental data regarding the functions of these genes in single-celled organisms remains limited. Research by biochemist Todd Miller of Stony Brook University in New York and his colleagues, for example, demonstrated that while tyrosine kinases exist in great numbers in choanoflagellates, they lack the tight regulation found in animal signaling pathways, suggesting regulatory elements may have been key to the evolution of multicellularity. But this idea remains speculative, Miller says, as the targets of these enzymes in the unicellular relatives of animals and the details of their activation are still unknown.

“What we’d really like to be able to do is compare signaling pathways overall and see how they evolved,” Miller says. “We know a lot about the proteins themselves, but it would be great to have a glimpse into a simple pathway where we can begin to unravel what the core elements of the pathway are before layers and layers of additional regulatory elements were added, as we see in metazoan cells.”

To confuse matters more, the vast stretches of time that separate most multicellular organisms from their unicellular cousins—more than half a billion years, in most cases—make for a lot of uncertainty. And as sequencing studies raise more questions, phylogenetic studies are also throwing a shadow of doubt on the animal tree. For example, are sponges really the most basal animals, as has long been thought? A recent phylogenetic study performed by Dunn and his colleagues suggested that perhaps ctenophores (comb jellies) are the earliest diverging extant multicellular animals.4 “Either sponges or ctenophores are sister to all other animals,” Dunn says. “The answer you get depends still on the organisms you include in the analysis, the analysis methods you use, and what genes you look at.”

“In order to understand evolutionary transitions, you need to have a robust phylogenetic framework,” says Ruiz-Trillo. The more genomes are sequenced, the better the phylogenies get, and the more similarities and differences are recognized between multicellular organisms and their unicellular cousins. “It’s a really exciting time” for studying the evolution of multicellularity, King says. With so many open questions and more and more sequenced genomes available each year, “there’s a lot of low-hanging fruit.”

A multicellular model?

Animals aren’t the only multicellular organisms, of course, and thus not the only system applicable to the study of multicellularity’s origins. In fact, multicellularity is believed to have evolved as many as 25 different times among living species. So while the search for metazoan origins may be riddled with uncertainty, perhaps scientists can draw inferences from the study of multicellularity in other lineages.

Comparing brown algae to their unicellular diatom relatives, for example, researchers saw an increase in membrane-spanning receptor kinases, a protein family known to play a role in cellular differentiation and patterning in both animals and green plants.5 The independent evolution of more kinase genes in each of these lineages suggests that this family of proteins may have been key to this transition.

Of all the multicellular lineages, however, the volvocine green algae represent the best-studied and most tractable system for teasing out the evolution of multicellularity. In contrast to most other origins of multicellularity, which likely arose close to a billion years ago, the change to multicellularity in these algae may have occurred as little as 200 million years ago—possibly limiting evolution’s mark on their genomes. Furthermore, between the unicellular Chlamydomonas species and the most-derived multicellular Volvox there are several extant intermediate species, some of which appear to have changed little since their divergence from their unicellular ancestors. While recent evidence indicates a complicated evolutionary history, including multiple origins of some traits and reversals,6 this lineage nonetheless presents a phylogenetic road map by which step-by-step transitions can be inferred. (See illustration)

Volvocine algae are aquatic, flagellated eukaryotes that range in complexity from unicellular species to a variety of colonial forms to multicellular Volvox, some of which boast up to 50,000 cells. This transition involved a series of key innovations, including cell-cell adhesion, inversion, and differentiation of somatic and germ cell lines. Two species in particular have become models for the evolution of multicellularity—the single-celled Chlamydomonas reinhardtii and the 2,000-or-so–celled Volvox carteri.

As with animals, comparisons of their recently sequenced genomes have revealed that there are few striking differences among the genetic codes of these organisms that could explain the drastic differences in their morphology. “It was pretty disappointing at first,” admits developmental biologist Stephen Miller of the University of Maryland, Baltimore County, who helped to analyze the Volvox genome (the sequence was published last summer). “We were hoping to see differences that would point to explanations for why Volvox is so much more developmentally complex than Chlamydomonas, but that certainly wasn’t the case.”

Not only do the genes exist in Chlamydomonas, they are so similar to the Volvox versions that they appear to be able to stand in for missing or mutant copies in their multicellular cousins. Volvox’s glsA gene, for example, codes for an essential component of asymmetric division; glsA mutants can only divide symmetrically, resulting in adults comprised entirely of small somatic cells, with none of the large germ cells, known as gonidia, that normally give rise to the next generation. While the homologous protein in Chlamydomonas is only about 70 percent identical to glsA’s protein, it can restore asymmetric cell division when the gene is transformed into glsA mutants. “Its ortholog in Chlamydomonas is perfectly capable of carrying out the same function,” Miller says.

Similarly, invA is essential to the process known as inversion, which gives adult Volvox their spherical shape, with the gonidia on the inside and the small, flagellated somatic cells around the exterior. In invA mutants, inversion fails to occur due to the cells’ inability to move relative to the cytoplasmic bridges that connect them, and the gonidia are exposed on the surface of the spheroid. Just like glsA mutants, however, this phenotype can be rescued by the transformation of the Chlamydomonas ortholog, known as IAR1.

There are exceptions to this pattern, however, such as the appearance in Volvox of many new genes that encode cell wall or extracellular matrix (ECM) proteins, with a dramatic increase in the number and variety of Volvox genes in two major ECM protein families, as compared with Chlamydomonas. While Volvox carteri have only a couple thousand times as many cells as Chlamydomonas, they can grow to more than 100,000 times larger thanks to a dramatic increase in the amount of ECM, which constitutes more than 99 percent of the volume of a mature Volvox.

Another significant genetic change in Volvox becomes evident when examining the mating locus—a region on one chromosome containing sex-specific genes that dictate whether the organism will be male or female during the sexual part of the volvocine life cycle. A notable difference in the sexual strategies of Chlamydomonas and Volvox is the size of their gametes. While the sperm and the egg of Chlamydomonas are nearly indistinguishable and are produced in similar quantities, Volvox eggs are significantly larger than its sperm, and there are far fewer of them. This transition to oogamy, as it’s called, appears to be a hallmark of multicellularity.

“It’s a remarkably conserved trait,” says cell and evolutionary biologist 7

“Overall the two genomes are very similar, but the mating locus of Volvox kind of exploded in terms of size and context,” says Umen. “In general, things related to sex don’t follow the normal rules regarding evolution; innovation seems to be a really important part of sex.”

But how much can scientists learn about the evolution of the complex multicellularity exhibited by animals and other lineages from studying the volvocine algae? According to some, not much. Volvox represents a relatively simple form of multicellularity, with only two cell types and no organized tissues or organs.

“I think it’s dangerous to generalize too much,” says Stephen Miller. “Because [multicellularity] has evolved independently in each of these cases, there don’t have to be similarities in how it evolved. But I would guess there might end up being some common themes.”

One emerging idea is that complex multicellularity, such as that of animals, plants, and fungi, may have evolved only a handful of times, and that it almost always resulted from the division of a single cell into the components of the larger organism, King says. In contrast to slime molds, for example, which form via aggregation of neighboring cells, the earliest multicellular animals were likely to have evolved by failing to disperse after the mother cell divided.

Evidence of this comes from a recent study out of King’s lab that found choanoflagellates fail to form colonies when cell division is inhibited.8 If the earliest ancestors of animals were anything like modern-day choanoflagellates, this suggests that animal development from a single-celled embryo is core to our evolution, and not a secondary development.

Similarly, the volvocine algae all divide via multiple fission, where the nucleus divides many times before the cytoplasm splits to generate that number of daughter cells. “It’s a way of producing a large number of genetically identical cells all at once,” says evolutionary biologist Matthew Herron of the University of British Columbia. “The only thing you need to do to produce an eight-cell colony [is have] them to stick together.”

The evolution of Volvox
The volvocine algae are a model system for studying the evolution of multicellularity, as the group contains extant species ranging from the unicellular Chlamydomonas to a variety of colonial species and the full-fledged multicellular Volvox varieties. Comparing the biology of these organisms, evolutionary developmental biologist David Kirk of the Washington University in St. Louis proposed 12 steps that were key to this transition. Here are some highlights that were key to this transition (BioEssays, 27:299-310, 2005).
Lucy Reading-Ikkanda (diagrams and cells); SOURCE: David L. Kirk
Complexity breeds cooperation

Beyond the molecular and developmental logistics of evolving multicellularity, there is the added complication of genetic conflict. An incredible amount of cooperation is required for individual cells to come together and function as one, and with natural selection acting at the level of the individual cell, there will be significant evolutionary pressure to cheat the system and sabotage the success of the multicellular whole.

Sean McCabe

The collaboration of first a few, then millions of cells to create an entirely new kind of “individual” thus requires a shift in the level of biological organization upon which natural selection acts. In this way, the evolution of multicellularity can be considered what has been termed an “evolutionary transition in individuality” (ETI), where the unit of selection changes from a single cell to a group of cells—the newly evolved multicellular individual. Other ETIs include the congregation of replicating molecules to yield the first prokaryotic cells, the associations of prokaryotic cells to create eukaryotic cells with organelles such as chloroplasts and mitochondria, and the establishment of cooperative societies composed of discrete multicellular individuals, like eusocial insect colonies.

“The general principle is, in any of these kinds of transitions there’s always some form of cooperation that’s needed,” says Herron. “In the example of the ants and bees, it’s the workers that are being cooperative in the sense that they’re sacrificing their own reproduction in order to help the queen reproduce. And in multicellular organisms like us and Volvox, the somatic cells are cooperating in the sense that they’re sacrificing their own reproduction in order to help the reproductive cells reproduce.”

Sean McCabe

But such transitions are not always smooth, as conflict can arise when selfish mutations result in cheaters that attempt to benefit from the group without contributing their fair share. One of the first cooperative steps required for the evolution of multicellularity in the volvocine algae was the development of the ECM from cell wall components, which can be metabolically costly to produce. The ECM can thus be thought of as a shared resource, and cells that do not contribute to its production may still benefit from its existence, thus gaining a growth or reproductive advantage.


1. M. Srivastava et al., “The Amphimedon queenslandica genome and the evolution of animal complexity,” Nature, 466:720-26, 2010. Free F1000 Evaluation
2. N. King et al., “The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans,” Nature, 451:783-88, 2008. Free F1000 Evaluation
3. A. Sebé-Pedrós et al., “Ancient origin of the integrin-mediated adhesion and signaling machinery,” PNAS, 107:10142-47, 2010.
4. C.W. Dunn et al., “Broad phylogenomic sampling improves resolution of the animal tree of life,” Nature, 452:745-49, 2008. Free F1000 Evaluation
5. J.M. Cock et al., “The Ectocarpus genome and the independent evolution of multicellularity in brown algae,” Nature, 465:617-21, 2010. Free F1000 Evaluation
6. M.D. Herron et al., “Triassic origin and early radiation of multicellular volvocine algae,” PNAS,106:3254-58. 2009.
7. P. Ferris et al., “Evolution of an expanded sex-determining locus in Volvox,” Science, 328:351-54, 2010.
8. S.R. Fairclough et al., “Multicellular development in a choanoflagellate,” Current Biology, 20:R875-76, 2010.


Avatar of: Martinez Hewlett

Martinez Hewlett

Posts: 1

January 4, 2011

Interesting article. While we often speak of cancers as diseases of growth control, might it be better to think of them as failures of conflict resolution for somatic cells? In the multistep models of carcinogenesis, would it be helpful to think of the accumulation of changes as a series of violations of these conflict rules? If so, how would this change our approach to modeling cancers?
Avatar of: Dov Henis

Dov Henis

Posts: 97

January 5, 2011

BioCulture,(Swarm)Culture And Intelligence \n\n\nA. "Rooting for swarm intelligence in plants"\nResearchers argue for a type of vegetative group decision making usually associated with humans and social animals, and go out on a limb by also proposing that information may be transmitted electrically.\n\n\n\nB. BioCulture,(Swarm)Culture And Intelligence \n\n\nThe core (wordnet.princeton) definition of "intelligence" is "the ability to comprehend, to understand and profit from experience". These surviving abilities are different for different cultures, for the different phenotypes within a genotype, therefore each phenotype has its own specific "intelligence". \n\nAll biological entities are intelligent. It takes intelligence to survive, i.e. to temporarily constrain more energy in order to postpone the self-constitutional energy fueling the cosmic expansion.\n\n\nC. Multicellular organisms, including WE,\n- derive from communities of cooperative monocellular organisms, that\n- derive from cooperative associations of DNA (or RNA) genes, genomes, which are also organisms,\n that \n- were evolved, are produced and employed by RNA genes, which are Earth's primary base organisms.\n- All Earth's organisms are evolved RNAs.\n\n\nD. Shock yourself:\n- Imagine plants upside down. Their root system are their head/brain complex. \n- Other, non-self-replicating mass formats, f.e. black holes, are "intelligent", too. Even if they do not have "comprehension" and/or "understanding" mechanisms, they do, too, "profit from experience" and try gobbling mass or energy to prolong their temporary survival, to postpone sharing the fate of all spin-array mass-formats as fuel for expanding the cosmos, for reconverting the mass resolved at the big-bang back into energy.\n\n\nDov Henis \n(Comments From The 22nd Century) \n03.2010 Updated Life Manifest \n \nCosmic Evolution Simplified \n \nGravity Is The Monotheism Of The Cosmos \n \nEvolution, Natural Selection, Derive From Cosmic Expansion\n
Avatar of: L Grant

L Grant

Posts: 1

January 5, 2011

If we succeed in solving this problem, mankind will have the key tool with which to engage in the settlement of the universe. Send a little seed, and watch it grow.
Avatar of: Steve Summers

Steve Summers

Posts: 28

January 6, 2011

One of those rare `seminal' reviews.
Avatar of: Gil Lawton

Gil Lawton

Posts: 42

January 7, 2011

While I am an admiring fan of any and all "pure" thinking by the human mind, and those who push away at the frontiers of what is mistaken by some to be human "knowledge," I also reserve the right -- as I would propose ALL thinkers do -- to ask of self and others, "But where is my present set of opinions wrong?"\n\nTo call this skepticism, as I conceive of it, is a misnomer. That is, I embrace fully the fact that we humans cope by taking stances on basis of less than enough "information" to arrive at certainties. There's not getting around it. The ignorance just beyond the horizon of our certainties constrains we take stances, lest we simply roll over and quit exercising our coping abilities, and seeking satiation of our curiosities.\n\n(Please bear with me, as I am leading up to a point for thought about the article in subject here. But the point I would make must be given benefit of context in which to rest.)\n\nTo my way of thinking -- (yes, it could be wrong, so what?)-- even Sir Isaac Newton met himself, logically speaking, going and coming in opposite directions on the matter of empirical evidence and proor. How so? Well, he insisted that the only thing that could be relied upon was hard evidence, in the one direction but, when he reached the limits of his ability to prove what he preached, he copped out. He reversed himself on the subject of proof by declaring that the fundamental laws he proposed were -- get this now -- "SELF EVIDENT," as in, so obvious as to require not proof.\n\nTo my way of thinking, that is glaringly inconsistent, and any and every argument that has been thrown up in favor of Newtonian empirics strikes me as ungrounded. (It strikes me as hillarious that some who argue on basis of Newtonian empiricism fail to mention his religious convictions that somehow survived, for him, unmitigated thereby.)\n\nMy stance is that it is NOT intellectually consistent to insist that something is self evident until and unless one can certify it.\nAfter all, if the proposition that an object in motion will continue along its motion (its vector?) in the same direction (and same rate of speed) until and unless acted upon by an outside force, until an experiment is set up and conducted to remove all doubt. To set up the experiment, we would be constrained, to find a place outside the universe where there is "no other force" in play. Where would that be? As a mind experiment, it dashes up against the maddening problem that, in the context of the place and time where we would set up the experiment,we would face the dilemma that an object would have no direction of travel and not rate of travel there, if such things are only expressions of relativity between one object and another, or others. And, if we are so clever as to argue that, in view of the way things behave in the context of a grand milieu of forces exerted by other objects, such as by the theoretical bending of space time, what would be time, and what would be space, in that milieu.\n\nNo I am not saying Newton's so-called "laws" have not been a useful myth. I am just saying that just because we can set up such things as balls rolling down inclined planes, and make sure not to measure to more than a blunt level of accuracy, the results seem to point toward such a law. Also, I am all too happy to point out that, at different macros... or different levels of emergence of reality, if you will, laws can DIFFER. That certainly seems to be borne out by what seem to be contradictions at the level of emergence of quantum physics, does it not? So, okay, how LARGE would be a bowling ball, if relegated to a non-universe... a place having no other object in it? Would it be equivalent to the smallest particle of mass in our universe, multivers, or whatever? Or would it be equivalent to a galaxy? \n\nSo, okay, how does one dispense with the possibility that a bowling ball, if we could teleport it to the proper place for our empirical experiment, might explode into a big bang, or cease to exist or something. \n\nNewton made the answer simple for himself, and any who don't quibble over what a famous man says. We just "know" from a preponderance of evidence in this, our, milieu, that points to what would occur in that milieu. Oh, really?\n\nHow wonderful! Or, should I say, "How convenient."\n\nBut if science is the study of materiality (mass and energy) to the extent we can observe it, measure it, play around with it and see what results... then Newton's "object" is outside that realm. Wouldn't it be a shame if someone were to insist that it could not be mentioned in any class in school, other than a class in metaphysics?\n\nSuch dilemmas or paradoxes are legion. We could go on with them all day. \n\nJump forward to Immanuel Kant, if you will, and his (to my way of thinking which could be wrong)apologetic for pure argumentation for what is tantamount to saying "near enough to absolute proof is sufficient." We can argue that he implied that another time. \n\nMaybe reading him doesn't jump out and scream to you "cop out" as it does to me. But Kant, too, strikes me as having taken certain arguments as far as he could go with them, and then said, in effect, "Beyond that doesn't matter. It's not important. Science -- and oh, this is a beauty, can have all the "proof" it needs to make us sure it is right, without exhausting every twit of observations, measurement, experimentation... which reduces to an unspoken assertion, in my estimation, that "as close as we can get is close enough to provide... well, okay... "reasonable" certainty, which is as good as infinite certainty. \n\nHow often do we say, "I just KNOW, that's all. And that's all that matters"? Let a theologian say that and he's a nut. Let a scientist say it, and... 'nuff said?\n\nSo, when is sure enough, certainty? \n\nAnd, after answering that one, we can then ask where does Newton cop out? Where do Kantian's cop out. Where do quantum physicists cop out?\nOh, and I'd better not mention neo-Darwinists, or the patron saint, as it were, or the book of immaculate proof that genes are selfish. \n\nBut if I find such arguments at once both highly USEFUL and highly necessary in providing or defending certain unfalsifiable STANCES I would defend all day long AS SUCH, some would deem me to be unreasonable and insulting if I were even to ASK, "Could they be wrong?" So, okay, I won't ask then. \n\nI could be wrong but I have a personal stance that I should separate absolute certainties from unfalsifiable opinions. And if that is an insult to anyone's patron saint, or favorite rational model supported by a lot of circumstantial evidence he or she is aggressively seeking to bolster with more of the same, just look back at sentence one of this paragraph, and accept my apologies. \n \nConjecture has a valid and useful place in science, and so does circumstantial evidence. So,too, for that matter has any other myth. \n\nPlease forgive me if this seems abusive, too; but from where I live and think, if science relies solely upon knowledge necessary, sufficient and certain, then ALL the books of science in public schools should be burned, I would think. But, on the other hand, if science is the best we can do with measuring, observing, experimenting and rationalizing, then it's a wonderful tool for enabling us to progress from one level of ignorance to a another that is less ignorant.\n\nLet me take pains to emphasize that, in view of the latter of these stances in reference to what science is, and does, I strongly support all efforts by those greatest of minds which, in their finest hours, accummulate and document more circumstantial evidence, and those who form new syntheses, and those who argue and resolve upon consensus to defend in fair and respectful debate until so many anomolies are encountered that some new synthesis, less reminiescent of a \nSwiss cheese. \n\nSo, finally, I can get to the point I would like to venture about the subject article, and much of the rhetoric of biologists in general. Get angry with me if you wish, but I discern in reading the words of biologists, more so than physicists, that many of them mistake INTERPRETATION, and the taking of stances of assumptions, as "reasonable certainty," or what might be called Kantian certainty, if that does not roll him in his grave.\n\nDo you suppose that Kant ever dreamed a day would come when a scanning, tunneling microscope would measure so acutely as to discern that a twelve inch ruler, measured even to the width of a proton, would be a moving target... one engaged in Brownian motion, which presents only a statistical reality, whereby it cannot be conclusively said that the boundary is at this precise place, or that, or is subject to the paradox of super-position. \n\nWould anyone argue that splitting hairs that fine is not science? No way. But what if we were to say that a biologist who argues that, for every gap a deist objects to in the chain of events between a single cell and a current-day elephant is a continuous one. Perhaps it is. And I totally condone and support all efforts to find out. But clear and present certainty, based upon preponderance of current forensic evidence, with gaps in it. Point to gaps in physics, and lots of physicists take it in stride. Point out a gap in evidence in biology, on the other hand, and its an evil, ignorant, myth-only-based slap in the face.\n\nIf you've ever raised children, and endured the pangs and arrows of being accused of making their lives hell, when you just did the best you could and hoped they would mature into healthy, happy, well-adjusted adults who could make it on their own. You know there is a period, mostly in their adolescent years, when nothing you say is valid unless it happens not to stand in the way of something they want to think, or do. Then it's unreasonable, unfair, inequitable, judgmental, over-bearing, insulting,cruel... and worse.\n\n"Could it be," I wonder, "that the bio-science fields are in their adolescence, while physics has grown a beard?"\n\nAre biologist justified in getting angry and defensive as a result of being questioned in their stances on some things, by people who lack sophistication (or operant conditioning, or esoteric inculcation, or some such dreadful thing, so as to know what's reasonably certain) and therefore have no right to have an opinion, or no right to believe that the road to future rational models my veer off in a direction quite different than anyone as yet has supposed?\n\nMaybe biologists have been made angry and aggressive in defense of the current state of their progress in moving their field up, step by step, from baser levels of ignorance to slightly more enlightened ones. If so, it's a shame.\n\nBut it is a more blatant shame if, in being made arrogant and defensive they may have lost a bit of objectivity, and become overly entrenched.\n\nHey, I could be wrong. Maybe they could be wrong on a stance or two. \n\nAs for the assessment most intellectually satisfying to me, the greatest single need of science and the lay humans who cannot help but wonder where the facts end and the ego's take over, is a need for humility on both sides, and a willingness to listen and learn.\n\nBut if only one of these two parties to a misunderstanding is noble and rational, shouldn't that one be most desirous of admitting to a line between what is only conjectured and taken as a stance, on the one hand, and what is certain, on the other?\n\nMaybe neither side can do that.\n\nMaybe wisdom to know and admit the difference is just too much for any human to aspire to and attain.
Avatar of: Dov Henis

Dov Henis

Posts: 97

January 18, 2011

Enhanced D para D:\n\nD. Shock yourself:\n- Imagine plants upside down. Their root system are their head/brain complex. \n- Other, non-self-replicating spin arrays mass formats, regardless of size, f.e. black holes, are "intelligent", too. Even if they do not have "comprehension" and/or "understanding" mechanisms, they do, too, "profit from experience" and try gobbling mass or energy to prolong their temporary survival, to postpone sharing the fate of all spin-array mass-formats as fuel for expanding the cosmos, for reconverting the mass resolved at the big-bang back into energy.\n- The RNAs, Earth's primal organisms, most probably "profit from experience", too, when selecting an alternative splicing route ("Whence And Whither, On Life's Twist").\n , comment.\n\nDH\n
Avatar of: Babak Makkinejad

Babak Makkinejad

Posts: 4

January 20, 2011

I liked this article for 3 reasons:\n\n1- It confirmed the observations of Conway-Morris that the process of evolution reuses prior bilogiocal materials in novel ways.\n\n2- It rightly raised the fundamental question of when and how evolutionary process acts on assemblies of cells rather than cells themselves\n\n3- And pointed to a possible origin for cancer

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