Pabitra Mukhopadhyay

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Goodbye Mr. Darwin and the selfish gene?

Jaroslav Flegr, a self-described “sloppy dresser,” the 53-year-old Czech scientist has the contemplative air of someone habitually lost in thought, and his still-youthful, square-jawed face is framed by frizzy red hair that encircles his head like a ring of fire. He is trying to change the way we think about Darwinian Evolution.

He suspected that Toxoplasma Gondii, an obligate, intracellular, parasitic protozoan that causes the disease toxoplasmosis, and with which he is infected is changing his behavior subtly so that his ‘selfish’ genes are more or less now slave to those of the genes of the parasite. If what he thinks is true, Jaroslav is under more the selective pressure of the parasite than his own genes.

For fact, parasites inducing behavioral changes in hosts have been reported by many scientists. Toxoplasmosis is one of the most prevalent infection among humans. If you have affinity for cats, you are likely infected.

Jaroslav has come up with the idea of frozen evolution, which suggests that new adaptations by accumulation of random mutations happen only when their members are genetically uniform, i.e., only after a portion of the population of the original species has split off, balanced on the edge of extinction for several generations, and then undergone rapid expansion. After a short period of time,polymorphism accumulates in the gene pool due to frequency-dependent selection; and thus, in each generation, new mutations occur in the presence of different alleles and therefore change their selection coefficients from generation to generation. The species ceases to behave in an evolutionarily plastic manner and exists in this state until such changes accumulate in the environment that the species becomes extinct.

When you are a host, it is unknown in which direction your evolutionary future lies – survival or extinction.

So is it goodbye to Mr. Darwin or his celebrity proponent Dr. Richard Dawkins?

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    Dec 18 2013: Darwin never said that genes we're selfish.

    Dawkins on the other hand has a book with that title, and the title is often deeply misunderstood.

    I'm sorry Pabitra, but as with everything else that people think disproves evolution this is rather a magnificent(ly scary) example OF evolution...
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      Dec 18 2013: Jimmy,
      The debate actually does not challenge evolution but seeks to examine if it is time to question whether it follows a classical Darwinian philosophy. If frozen evolution hypothesis is established, the expressed phenotypes of an organism can no longer be credited to its genes rather, in a host-parasitic context parasite gene polymorphism takes control of the evolution.
      One can argue that half of humanity is crazy or our cultural diversity is the result of a parasitic infestation. I just wanted to know if we are ready yet to accept that possibility.
  • Dec 31 2013: Darwin did not propose the selfish gene hypothesis. the selfish gene is Dawkins'. Therefore, if the selfish gene hypothesis/metaphor was wrong, then it would be goodbye Dawkins, not goodbye Darwin.

    But the whole thing with toxoplasmosis is so wrong that I would not know where to start. Do the toxoplasma's genes get benefit from controlling the host or not? Well, the fallacy is on looking at the hosts genes no longer being benefitted, while other genes are. This case was clearly explained ever as far long ago as Dawkins' book "the selfish gene" itself. It was further explained in "the extended phenotype."

    Therefore if those are the words of Jaroslav Flegr, then Jaroslav has to learn to look more carefully what he/she is saying.

    The problem with the second part [EDIT: frozen evolution] shows poor understanding of population genetics. Some people should really stay away from evolutionary biology, or consult with someone more embedded on the subject before opening their mouths, Of course, it could be that this person knows evolutionary theory and population genetics well, but makes these declarations to gain notoriety.
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      Jan 2 2014: "The problem with the second part shows poor understanding of population genetics. Some people should really stay away from evolutionary biology, or consult with someone more embedded on the subject before opening their mouths,"

      What is the second part?

      Who do you mean are 'some' people?

      Why do you think these 'some' people should stay away from evolutionary biology?

      Jaroslav Flegr is a noted evolutionary biologist himself. Here is his bio and work.

      I think it is good and simple English and readable enough (papers under evolutionary parasitology) before coming to any quick assessment of his work and this debate.
      • Jan 4 2014: The second part is the frozen evolution part.

        "Who do you mean are 'some' people?"
        The guy you cite in the OP, for example.

        "Why do you think these 'some' people should stay away from evolutionary biology?"
        Because if they don't understand those concepts properly they can only come up with these unfounded ideas (like frozen evolution). The only effect they have is a lot of people misunderstanding evolutionary theories. for example, he's got you thinking that the selfish gene was an idea by Darwin, that a parasite controlling the host behaviour was a counter-examplke for the selfish gene (far from it), and that there's such a thing as "frozen evolution" which is but a mistaken way to look at population genetics.

        The link you provided shows that this guy is first a parasitologist and then a molecular biologists specialized in parasites. Not an evolutionary biologist proper. It's right there in plain English. But I did not need to see that since what you wrote shows enough poor understanding of evolutionary theory in general and of the selfish gene hypothesis/metaphor in particular for me to notice that the ideas lacked a proper foundation. I explained. You don't have to believe me, of curse, but at the very least you should be able to verify, for example, if Darwin suggested anything like the selfish gene (hint: by Darwin's time genes had not been described). It should also be easy for you to notice that, since the parasite's genes are benefitted, the selfish gene stands. That claiming the opposite shows that this person looked the wrong way (the hosts' genes, rather than the parasite's genes) when he made his assessment.

        See ya.

        P.S. I did not come with a quick assessment. The assessment took me years and years of learning and education in evolutionary biology. From reading the books by Darwin, Dawkins, E.O. Wilson, Gould, etc, to specific courses and participation in research.
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          Jan 4 2014: Thank you for clarifying.
          As far as I know and correct me if I am wrong, evolutionary biology, as a sub-field of biology has not emerged as an academic discipline in its own right until 1930 to 40.
          " It was not until the 1970s and 1980s, however, that a significant number of universities had departments that specifically included the term evolutionary biology in their titles, often in conjunction with ecology and behavior. In the United States, as a result of the rapid growth of molecular and cell biology, many universities have split (or aggregated) their biology departments into molecular and cell biology-style departments and ecology and evolutionary biology-style departments" Wikipedia says that.
          So I am not sure if any senior scientist will at all have a masters/bachelors on evolutionary biology. Flegr did MS on cytology - so I am not clear how you think he is first a parasitologist and then evolutionary biologist. His research activities clearly show work in the area of evolutionary biology.
          I think we both can agree that we cannot be too technical about the science involved in this debate, but I do not think any part of my OP can lead one to think that I am thinking 'selfish gene' was Darwin's idea. It was a hypothesis by Richrad Dawkins that has gained popularity is scientific community.
          Nor does 'Goodbye Mr. Darwin' mean Jaroslav's hypothesis of 'frozen plasticity' is anti-Darwinian in essence just like special relativity was not anti-Newtonian. Science simply does not work that way.
          Flegr's work seeks to provide ways to explain adaptive traits in sexual reproduction of species, which Darwin could not very successfully do nor did Richard Dawkins.
          What do you think are the gene's of the host? Altruistic genes? Did Dawkins hypothize 'selfishness' of genes only for the parasites? Also it may be very interesting to note that the parasitic genes freely proliferate through sexual reproduction.
      • Jan 4 2014: Hi Pabitra,

        This guy is first a parasitologist because that's what his main publications are about. Even several of those he labels as "evolutionary biology." His education clearly did not include the necessarily harsh discussion on evolutionary biology. I gave you a few examples that betray his lack of proper training.

        Reading through this guy's publications I gather a sense that this guy is talking inside an echo chamber. He is lacking a key need in scientific research, the voice of dissent within his own research group and collaborative network. This way he would have avoided some all-too-obvious mistakes. For example, I read the guy saying that sexual reproduction would work against natural selection. Yet, for example, some experiments on directed evolution show that recombination of selected variants can speed up evolutionary changes by orders of magnitude. The same is true in simulations. And that was just the first few paragraphs of his introduction. By the way, Darwin did not have any problems explaining evolution in sexual organisms at all. All his data was on sexually reproducing organisms to begin with. Sure, later on scientists started wondering about problems with sexual reproduction and evolution, but the problems were more about the risks of sexual reproduction, such as mate displays that make organisms easier targets of predation, not about the advantage of recombination. So, this guy has a lot of things quite wrong.

        As per the "goodbye Mr Darwin," the obvious effect is to mislead people into thinking that the whole of evolution is wrong. That's what "goodbye" entails, while Darwin represents the whole of evolution in the minds of most of the public.

        The selfish gene is about the unit of selection. Dawkins proposed genes as such. If some genes enslave other organism's genes makes no difference. Selfish genes still in effect. As I said, Dawkins explained this in his books. (There's more, but the books explains better than I could here.)

        I'm out.
  • Dec 27 2013: The selfish gene is nothing but the need . The need of an individual & at the stage where it requires to mutilate, to achieve is the stage were not only the individual but the full society feel it that way
  • Dec 27 2013: Hi Pabitra,

    A couple of observations: Biology is dynamic by definition and has a non-cyclic aspect to it as reflected in biological evolution.

    The concept of the niche is fundamental to what makes biology a science. No two separate species can occupy the same niche at the same location indefinitely. It's obvious that niches have expanded during the history of life on earth. Many of these expanding niches have come about dependent on other living organisms and as their populations expanded opportunites for new species in the form of viruses, mistletoe, etc., were added to the phylogenic tree.

    If I understand correctly Jaroslav Flegr is delving into some interesting potential consequences of how this host parasite relationship could influence the hosts in ways that could influence or interfere with the basic mechanism (genes) that enable the biological evolutionary process. I presume this influence would have only come about after the niche was invaded by a species. It's hard for me to think this would alter the basic concept and theory of biological evolution, but rather help define its evolving subtlies.

    It would not surprise me that Professor Flegr is onto something. Perhaps a future TED Speaker with an idea worth spreading. I am looking forward to reading what he has to say.

    I'm on cold medication so I hope I'm making sense.
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      Dec 28 2013: The problem, Dan, with the idea of biological niche is that of a scale. As we look at the ecology, which is biology expressed in grand scale, niche is obvious. If we look at genetics, which is biology expressed in the minutest of scale know to us, the boundaries defining niches start to become blurry.
      It is time we start defining the unit of life. To me it seems to be an organism having an independent life with a copy mechanism to reproduce and having a given life span and evolving in a given environment. To me it also seems that the idea of biological independence is rather contrived, the copy mechanism of reproduction is all but accurate and the environment is easily exchangeable with other species.
      • Dec 28 2013: Pabitra, I must admit I can't connect where you are coming from with your explainations, nor Flegr's postulate.

        Richard Dawkin's with his observation of memes (a word he coined) was able to explain how the affects of our human genetic constitution is not the sole influence of our life circumstances. We can, and have, independently influenced our niche and overall survival success by our behavior and cultural knowledge. Interestingly enough in some cases by negating the negative consequences of individual genetic phenotypic expression via medicine, and also in so many other ways via communication, inventiveness, and on and on.

        As already pointed out Flegr's claim seems more likely to be the consequence of the blind unfolding evolution of the living biosphere of which we are part, including serving as a niche for numerous other living organisms. These consequences may well often be esoteric, cumulative, selective, beneficial, detrimental, etc.

        I don't see a case here for his postulate.
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          Dec 29 2013: What do you think is the biological niche of T. Gondii? It has two aspects of its existence/life, one sexual that happens only within the stomachs of cats and another asexual part that can can happen inside the bodies of almost all warm blooded animals. Flegr's postulate in one part cites its strange life where T. Gondii arguably influence the non-cat hosts' brain functions subtly (Flegr himself is a host) so that the host organism's biological goal is compromised against the parasite's. Looked from T.Gondii's perspective it doesn't seem to have a niche, or if it does have one it is too complex and huge for its size.
      • Dec 29 2013: Hi Pabitra, in response to the concept of a biological niche.

        T. Gondii may have two physically independent aspects of its life cycle, but they are not independent of one another. The niche of this species like all other species of life would include all the physical needs necessary which enable it to survive as a species. The essential niche of this organism is in the belly of it host, but from there it is able to roam to intermediate hosts.

        This is my understanding of basic biology and it is an important concept because it is a fundamental component to understanding evolution. I don't see how better understanding T. Gondii via Jaroslav Flegr publications contradicts how evolution in known to work as originally postulated by Charles Darwin and beautifully explored by Richard Dawkins.
        • Dec 29 2013: Dan, Pabritra,

          As I read your posts I thought of how certain creatures gather in a certain location to reproduce and are abele to roam far from said location ... in the case you are talking about its the belly of one creature and the bodies of other creatures... in the one I was thinking about its a certain bay rather than the arctic waters ... and as I write this I consider how it could even be a certain river source vs the open seas ... or certain beaches vs the open seas.... or certain islands vs the vast territories they normally roam most of their lives... In other words the idea of reproducing in a particular place while living elsewhere most of their lives is rather common... there are even certain bugs that live under the ground most of their lives and come out to reproduce at a particular stage... In the case of your conversation it seems the creature likes to reproduce in the stomach of cats and live elsewhere... I wonder if it develop and subtlety influences hosts behaviors so as to induce them to live together in order to facilitate it's own existence... or if it just took advantage of the particular niche that the hosts created by living together... in a more civilized context ... to companies form where there is a workforce and favorable conditions or does the workforce live and the favorable conditions be created where companies form?
      • Dec 30 2013: Hi Esteban,

        One of the key aspects of the natural evolution of species is that it is blind as opposed to designed. The selective pressures and opportunist influences is what directs change in a given population expression by favoring variation within individual offspring members of the population, or favoring chance changes in the individual genes passed on to the offspring. Also a niche is characterized by a range and often reflected in the population of a species. The Douglas fir tree tends to be more magnificent in the center of its range in the Pacific Northwest than on the outer limits of that range. In other words these individuals tend to be more fit.
        • Dec 30 2013: Dan,

          When one species develops the capability of molding it's surroundings to expand and accommodate the rage over which it prospers the natural evolution can come into the influence of that one species whims and become designed and guided evolution... akin to breeding of dogs for particular traits... or 'genetically' modified plants/animals/environments. If we consider memetic influences into the human development evolution we may even observe more complicated relationships... do ideas tend to our needs or do we tend to the needs of ideas? Maybe its a bit more complicated as we tend to each-other wellbeing... the gardener-plant caring for each other breathing in and breathing out in a synergistic cycle thanks to the collaboration with the other...
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    Dec 21 2013: This talk appears to be strikingly relevant

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      Dec 21 2013: Yes it is Arkady. There is marked similarity between biological realm and cultural, the later grows, spreads, infects, develops immunity or gets perished almost like biological entities. There is a great insight here that we may seek to examine.
      Just like biosphere comes under periodical waxing and waning of parasitic, germ based influences globally that we may choose to call pandemic, the thought-o-sphere experiences the same incidence. Why and how exactly that happens is an intriguing question but you may like to just shift through the TED conversations of the past month and so to check how many of those involves memes like 'virus', 'evolution', 'survival', 'spread'.
      You will be amazed.
      When I showed that to my wife she said, are you sure these people do not conspire together?
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        Dec 21 2013: I like Dennett's talks not as much for what he says as much for what he implies. This talk has thoughts intersecting with your thesis on more levels than just meet the eye. First, he starts with an example from biology where a parasite changes behavior of an intermediate host to get to the host of its preference. This example is, essentially, the same as your example with toxoplasmosis.

        His talk also intersects with what I said below regarding the role of non-material things, such as ideas and will in biological evolution. Dennett says in his talk:


        Well, I wouldn't be so sure about other species. There are known examples when a dog risks its life to save another dog or its master, for example. This behavior cannot be explained by the desire to maximize the number of grandchildren.
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          Dec 21 2013: I too like Dennett's talks because they try to demystify consciousness. One of his focus areas is explaining consciousness based on biology.
          I think the twist in the tale is that untimely its biology but not exactly the way Darwinist's think. The selfish gene idea gave us a way to see what exactly is a unit of life. With parasites the boundaries become hazy. If one thinks about the genetic units of one's own ruling the things, well, humans are loaded with foreign units that are essential for its living, aren't they. I may not live at all if I am stripped of every single piece of non-human genetic material from my physiology. They are part of me and they determine how I live. It doesn't have to be parasites. Our alimentary systems are practically run by bacteria. Even mitochondria, our cells' battery used to be an independent organism once.
          With so much of biology involved, who is maximizing his grandchildren through us is a big question it seems.
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        Dec 21 2013: Here is another Dennett's talk which I have in my favorites

        I love it for the way he delivers his message. In the beginning he compares consciousness to street magic. When it's explained, people get disappointed because the magic disappears. Then he proceeds to explain how consciousness works, showing on a few simple examples that we see what we expect to see whereas the actual reality is something completely different.

        The funniest part of the talk is the comments. Many people are either disappointed or frustrated that Dennett didn't explain anything. Well, he did. That's exactly what he said - that reality is not what we expect it to be. And, in a twisted way, it applies to his presentation itself. People who are disappointed with his presentation simply don't get the point. The explanation of consciousness is not what we would expect.

        In a similar way, scientists would think that species are driven by the desire to perpetuate their genes. Whereas, the examples of mice infected with toxoplasmosis or the ant climbing up the grass blade, they appear to promote someone else's genes.

        And why do we have to promote any genes at all? Where does this desire come from? What's wrong with Mars and other planets without life?
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    Dec 19 2013: can you be more precise on the parasite you have in mind? Because if parasite should take over out system is more or less we are infected with a disease.
    If i'm wrong pls pull me back on the track.
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    Dec 19 2013: Pabitra,

    I wanted to thank you for another perplexing problem. I will add it to my collection. I downloaded Flegr's book and will read it when I have time. It has valuable insight not only on evolution and biology, but on science in general.

    This question seems to belong to a huge class of paradoxes connected with Russell's paradox http://plato.stanford.edu/entries/russell-paradox/. The paradox considers sets which do not contain themselves. If we consider a set of all such sets, we come to a contradiction when we try to decide whether such set contains itself. The "Barber's paradox" is of the same nature. Most paradoxes dealing with omnipotence and omniscience are of the same nature. The controversy of whether a fetus is a part of mother's body or a separate legal entity is another example. Controversies around "common good" vs. "individual good" seem to belong to the same category. "Where did the universe come from?" - another example. They are impossible to answer by logic.

    Is the parasite a part of our body or a part of the environment? But, even deeper than that, is our own body a part of its own environment? The answer seems to be "yes". Then, the distinction between the body and environment seems to disappear. Perhaps, this distinction makes sense in some contexts, but not in others.

    So, without going into details, it seems to me that your question does not have an answer. But, as usual, it's a great pleasure to think about it - just to realize how limited is our language and ability to understand things and "dissolve" these limits of our understanding (another paradox).
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      Dec 20 2013: Arkady,
      Paradoxes are beacons standing on their heads trying to attract our attention towards the way we reason.
    • Dec 20 2013: Arkady,

      Rather than get entwined into a paradoxical self-negating stand I prefer to follow a simpler way.
      The statement "there are no absolute truths" creates a paradox
      The statement "there are absolute truths" doesn't create a paradox
      Notice the self-validating point in the last statement.

      i find curious how relativists resort to absolutes rather than simply resort to relatives... To me an absolutists can always be both an absolutists and a relativists at the same time by choice (which sort of makes the distinction between being a relativists and an absolutists quite irrelevant). Note that the relativists can only accomplish such a feat in the particular case when what they had chosen as a relative truth happens to correspond to the absolute truth... Personally I rather take the stand where I can always be both rather than the stand where I can only be both in one particular case. The stand where what be be what be is much simpler than the stand where what isn't is what is and what is is and what isn't. Sure one could work in either one so long one kept track of the appropriate distinctions its just much simpler to work in a singularity where one win-or-wins than a confusing duality where one loses when one wins and wins when one loses (and ends up always loosing).

      As you said "Perhaps, this distinction makes sense in some contexts, but not in others". Careful with the ways we reason... it may be dew to the 'subtle influences of parasites' (biological ideological and others).
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        Dec 20 2013: According to this article, http://en.wikipedia.org/wiki/Self-refuting_idea, self-refuting ideas can be of two types: a self-consistent tautology (e.g. "this statement is true") or a self-contradiction (e.g. "this statement is false"). "This statement is true" is true or false, depending on what you believe about it. If you believe, it's true, it is so. If you believe it's false, it also confirms that belief without contradiction. It's interesting to observe that this self-consistency is absolute.

        "This statement is false", on the other hand, contradicts itself. As we go through logical steps trying to find out if it's true or false, it switches from true to false in every step: "if it's true, then it's false, then it's true, etc." In digital circuits, an equivalent of such statement is called a "ring oscillator" - a circuit that picks up noise and starts oscillating between logical high and low.

        Statements relative to ourselves are absolute. Your right hand is always on your right side, no matter where you face. The right hand of another person is also on your right if you face the same direction. But if you stand against each other, the other person's right hand will be on your left. This is how it is with moral statements. They are absolute for a given person and same for people with common interests, but turn into opposites when two people oppose each other. So, yes, things can be absolute and relative at the same time. Absolutism is relative (things can be absolute in certain contexts) and relativism is absolute ("everything is relative" or "nothing can be absolute in all contexts").

        It's a convoluted subject. The wikipedia article gives a good, although incomplete, overview of the issues involved. There is no way to coherently explain this issue because language is logical, and this issue deals with the limits of logic. But it's possible to understand this issue enough to recognize questions without answers.
        • Dec 20 2013: Arkady,

          I like what you said about " It's interesting to observe that this self-consistency is absolute".

          "This statement is true" is true or false, depending on whether the statement happens to be true or false... what one believes about it takes us to a whole different domain... In a way one stand can give each what they want while still giving them the same thing. Take the sustainable-desirable-congruent with life ways, it gives each what they want while still giving them the same thing (sustainable-desirable-congruent with life ways). Ending up in a place with only good; on the one hand is a reward to those who desire good and and on he other hand its a punishment for those who desire bad. Likewise 'may God give you abundantly of what you desire' can be a blessing or a curse!

          As you pointed certain ways lead into an oscillating back and forth rather than into a definitive position. BTW moral statements are absolute... those who say that good is bad and bad is good find it bad ... In other words it turns into opposite by those who oppose the good. I am glad that you conceded to the fact that things can be absolute and relative at the same time. I do see that you then when into the convoluted subject of 'Absolutism is relative and relativism is absolute' rather than into the straightforward notion where 'Absolutism is absolute and relativism is relative'...

          There be ways to coherently explain these issues using language and logic, independent of the fact that this issue may deals with the limits of logic, but even-though it's possible to understand this issue some choose to think its impossible and choose not to do what be required to understand it... sort of creating a self fulfilling self-consistent prophecy... in a way its a bit 'esoteric' those who know know and needn't be told and those who don't know while they may be told will not understand it... they could get it, they just choose not to get it...:-)
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        Dec 21 2013: What makes sense doesn't require an explanation.
        • Dec 21 2013: Often I read someone state "that doesn't make sense" when the truth of the matter be "someone can't make sense of that" while "somebody can make sense of that" ... in other words what be be what be and weather some individual can make sense of it or not is a whole different matter... Often individuals project their notions and thoughts unto reality and then claim reality is as they think and conceive it... when the truth of the matter be that what be be what be... and what one thinks of it be what one thinks of it ... sometimes there being a correspondence between what one thinks to be and what happens to be... I would rather stay away from getting too deep into this conversational rabbits hole... I am sure you and others can do a wonderful job... I was sort of drawn into this because of the mention of paradox and the work I have done related to transcending dualistic notions... keep in mind that when someone who is wrong tells somebody who is right that "somebody is wrong" they are somewhat validating that someone is wrong and somebody is right. If someone who is wrong where to say "somebody is right" we would have to figure out if its because someone recognized what is right or because somebody is wrong... as you mentioned previously 'It's a convoluted subject'. I like to say that one can twists the twisted straight ... of course if one makes just the appropriate and specific twists required... as I just said a couple of sentences back " I am sure you and others can do a wonderful job..." I hope that you and others actually do a wonderful job!
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      Dec 21 2013: Arkady, the philosophical contemplation as to whether or not a parasite is part of us is of not much practical relevance if as a result of this parasite invading your body, you are getting sick.
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        Dec 21 2013: Provided always how you define sickness (the semantical scope of the word included). When a virus gets to someone's brain, live their merrily without making one ill (meaning no obvious reason for a medical treatment) and subtly influences one's behaviors like dress sense, personality and mental capabilities, one borders on the doubtful boundary between sickness and health.
        I never know whether the cat loving driver running the bus I am in is Toxo positive but it can make the difference between life and death of a lot of people.
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          Dec 21 2013: Pabitra, in general you don't know anything at all about your bus driver. He could as well be a lunatic, alcoholic or whatever else one could dream up, without being toxo positive.
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        Dec 21 2013: Note that the parasite does not harm you. It causes you to harm yourself. The philosophical question is whether we can willfully resist this influence of the parasite or are we doomed to do what the parasite causes us to do. How much can we resist the influence of the environment?
        • Dec 21 2013: Consider that 'the parasite' may be biological, ideological , sociological and even energetically in form (and a couple of other alternatives)... to what extent the host is responsible for what they do under the influence of such stuff? the notion that the parasite does not harm you while it does causes you to choose to harm yourself could involve a bit of play of words... Who is responsible for 'the seduction': the seduced, the seducer, the circumstances around the event,the spirit of seduction that possessed each of the previous stakeholders? Does acting under the influence of... being possessed take away the individual responsibility? As you mention "The philosophical question is whether we can willfully resist this influence of the parasite or are we doomed to do what the parasite causes us to do. How much can we resist the influence of the environment"?

          To what extent does the parasite actually not harm you? To what extent does the parasite seduce you to harm yourself?
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          Dec 21 2013: It depends what you consider "harm". If the parasite changes something in my neural structure, then I would consider that very much a harm.
          The parasite doesn't cause, for example, schizophrenia, but changes something in the brain that eventually can lead to schizophrenia (and other problems).
          Not sure how you would be able to resist whatever the parasite causes, but if as a result you get schizophrenia you can get treatment for that.
          Resisting also seems difficult because in order to resist you first need to know that you got an infection, which most likely isn't the case.
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        Dec 21 2013: We have many parasites in our body without which we cannot survive, such as acidophilus bacteria. They also affect our digestion and neural system. Why do you think, it's "your" neural structure, anyway? Aren't you just an "environment" for the parasite, it's "habitat"? Why can we change our own habitat for our own benefit, but when a parasite does so, we consider it "harmful"? Aren't humans often acting as parasites in the ecosystem of the Earth?

        I don't expect answers to these questions. I'm just offering a perspective.
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          Dec 21 2013: We have a lot of micro organisms in and on our body but not parasites. Those are different.
          Btw, L. Acidophilus is not a parasite. A parasite is any organism living on/in its host and deriving nutrients at the host's expense.
          In any case, I don't enjoy parasites using my body as their playground. Do you ?
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    Dec 19 2013: Very good discussion going on....
    My thoughts are , what Jaroslav is saying is rather stregthening Darwin's proposition about "VARIATION".
    Well the differences are in how "VARIATION" happens , if I have understood the discussion here well.
    What Gerald is considering is that Parasites are part of environment from which actually the selective pressure for mutation coming in, but I feel Pabitra that is where differences of opinion are coming from.
    Like Gerald in my thoughts also , I consider parasites to be part of environment.

    Whether something is disease or not as pointed out by Herald, can be another subject for long debate. This something like what is NORMAL mental condition and what is not which sometime back I came across while studying depressive conditions or Schizophrenia. Hallucination or delusion someone with specific mental condition goes through are REAL experiences to them , which is unreal to all other who are wit so called stable Mental Condition.

    Molecular genetics was not that developed at the time of Darwin, moreover Genetics & Theory of Evolution didn't converge together that well during Darwins time. Darwin rather drew a very much "Helicopter View" on the process of changes happening in nature.

    So my understanding is that with the evidences of parasitic influence on mutation is rather strengthening Darwins proposition of VARIATION , STRUGGLE For Existence " Survival of the Fittest" as well as Natural Selection.

    Thanks Pabitra for bringing a thought provocative discussion.
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      Dec 19 2013: I cede to Gerald and you in accepting that yes parasites are also part of the environment of the host, because unless that is not the case the parasite host relationship will not develop at the first place. Well may be I should call it habitat or favorable environment?
      This is exactly the heart of the debate. Whose genetic expressions we are in the end? Our own or the parasite that infests us?
      Allorecognition and rejection of non-self part play an important role in maintaining genetic homogeneity throughout the life of an individual organism by preventing invasion of genetically different foreign entities that might parasitize the organism. What baffles me is that how come the parasites evolve to get past allorecognition of the host in as much as fooling its immune system whereas the hosts always lag in evolutionary terms not be clever enough to save themselves. They both are in the same environment, aren't they?
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        Dec 19 2013: Pabitrada , I am not sure from where Gerald came in, the point from where I am coming is....... here I was considering the cell itself where the gene is lying as it's macro environment. The parasite influencing the gene is also living in the same macro environment of the cell. From that sense it's part of environment of that gene. But for the host as a whole that becomes part of it physiological of biochemical environment.

        Other than the parasite host relationship , in the biological kingdom there are also other relations which you are aware of i.e. symbiotic relationship or commensalic relationship and those also I feel part of the micro environment.....something like a tiger is part of the environment for a deer in the macro environment of a forest. In food chain Deer & Tiger has a predator prey relationship which is analogous to host and parasitic / symbiotic / commensalic realtion.
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          Dec 19 2013: Interesting point made Salim, thank you. I was mentioning environment as more macro term than the cellular environment of the host body. In fact I recognize parasites as independent genetic entities from the hosts which by nature require a host's body to live and complete its life cycle.
          Moreover, symbiosis or commensalism is fundamentally different in terms of biological goals of organism from parasitism as parasites benefit at cost of host's harm. Allowing harm of an organism without developing a evolutionary antidote seems to be a weak argument for evolution itself. Flegr's hypothesis attempts to explain this as frozen plasticity of evolution as far as the host is concerned.
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        Dec 19 2013: Welcome Pabitrada and you are right that parasites are independent genetic entities from the host as it is for Tiger Vs Deer. In the totality of ecosystem of forest they again becomes part of environment.

        You definitely are aware that there are some viruses which displays basic features of life when those are in host body , if outside those are like non living things. Those viruses are considered to be the junction between living and non living world.

        Grasping concept of evolution seems to be easier when one goes into micro level look into the simpler form of life. More complex the species becomes more difficult it is to grasp evolutionary process at least to me.

        If I bring more analogy from physical world and focus on radio active matters the process of change from one matter to another becomes easier to understand. Same applies to biological world.

        I need to read about Frozen Plasticity and Flegrs hypothesis to understand this new concept. Thanks for your reference.
        Have a good day
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    Dec 19 2013: Dawkins must adapt or go extinct.
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      Dec 19 2013: :) I think professor Dawkins will love that!
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        Dec 19 2013: He might love the idea, but I'm not sure how much he loves to adapt his views. He seems to be pretty frozen in some of his convictions. People frequently love ideas until they realize that these ideas apply to themselves. :-)
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    Dec 18 2013: " its genetic code is homogeneous" -> what does that mean? Please... in you own words.

    "If our behavior is subtly changed under the influence of parasites taking over our neuronic pathways, we are nor not really changing under natural selective pressure."
    --> Yes we are,,, it's just that parasites have to be taken into acount as part of the environment. That's no news...
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      Dec 18 2013: I am not sure what exactly you mean by 'your own words'. These are my own words.I just have to hope that you understand genetic homogeneity and heterogeneity.

      When a parasite is highjacking an organism's neuronic path ways in as much as inhibiting it's natural evolutionary instinct of saving its own genes it is acting against its natural selection in a fundamental way. A Toxoplasma Gondii infected male rat finds the smell of cat urine (cat pheromone) sexually attractive, by that the parasite is increasing the possibility of the rat ending in the belly of a cat where the parasite can sexually reproduce and complete its life cycle. The parasite is neither part of its favorable environment which we may consider its habitat nor the infected rat's behavior is a phenotype of the rat's genes. It is news.
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        Dec 18 2013: I think Gerald was mainly asking for an additional explanation that would be easier to follow for those not in the field.

        I think your example here helps.
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        Dec 18 2013: Not it isn't news. What the selfish gene says is that selection happens at the level of the gene, not the individual or group or species (unless it benefits the gene). Who cares of one's "evolutionary instincts" (whatever that means) ? Either the gene causes the environment to replicate it, or it doesn't.

        "nor the infected rat's behavior is a phenotype of the rat's genes"
        It isn't, because it doesnt count on getting toxoplasmosis or getting run over by a truck to get its genes down a generation.
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          Dec 19 2013: Well Gerald, I guess you are better informed then :)
          To me, and I think to a lot it is news. The more I think about it it appears to be so plausible and it never struck me as a possibility.
          Parasites abound in nature - their ways were not studied that much so that a parasitic genetic polymorphism can be seen as the more general case of evolution rather than genetic mutation and adaptations under natural selection pressure. It may explain many strange extinctions in the past and possibly many unlikely selection of a species over a more (apparently) likely one.
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        Dec 18 2013: "The parasite is not part of its favorable environment which we may consider its habitat"
        Obviously it is, or that environment wouldn't allow it to reproduce.
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    Dec 18 2013: I don't understand this theory, Pabrita. Do you? If so, would you kindly explain it using your own words?
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      Dec 18 2013: Well, as far as I understand the theory suggests this (forgive me it is over simplified).
      The gradual and continuous evolution of an organism through genetic mutations under the selective pressure of the environment as thought by Darwin is not the actual case. When speciation takes place and a new organism splits from its ancestor, its genetic code is homogeneous and it is only at that time the organism goes through rapid evolutionary changes through adaptations. Soon enough the genetic code develops different 'morphs' and the same organism starts exhibiting different traits. Enough scientific evidence that parasite gene polymorphism or parasite-selected mutations in the host can lead to a situation when the host organism's evolutionary plasticity is lost. The host organism then becomes extinct under changing environment.
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        Dec 19 2013: Hi Pabitra.....what parasite do you have in mind ?
        If a parasite takes over your neural pathways then I'd call that a disease but has nothing to do with natural selection beyond the possibility that if you die from it nature removed you from the gene pool.
        Do you think that parasites highjacking neural pathways is something very common ?
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          Dec 19 2013: Harald, yes I think parasites highjacking neural pathways is way too common, certianly more common that we care to think.
          After I read Flegr's hypothesis and about the current research on parasite induced behavioral change, I am not really sure about if I can categorize it as 'disease'. I mean if results show that almost half of human beings can be Toxo-positive and it otherwise does not show in any way like fever, pain or medical conditions to be worried about, but just change our behavior very subtly making us more risk prone, reclusive and forgetful, overtly social for females all because the parasite manipulates us in large populations to facilitate its own survival - I think it is more than disease.
          Scary thing is, Toxo is just one parasite presently under popular microscope. There are truckloads of these in our bodies. Research indicates that during certain kinds of influenza, people become excessively social and outgoing because the virus needs to be spread through sprays of body fluids through sneezing.
          Do you think schizophrenia is a disease? Toxo infested population have a clear connection with schizophrenia. For example Toxo has a gene that encourages release of dopamine in situation normally an organism is expected not to, the consequences are easy to imagine.
          When the parasites have such access into our systems and such subtle control over our behaviors, it is hard to think about evolution taking place in a linear and gradual way with any level of predictability.
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        Dec 19 2013: Pabrita, while it seems to be true that a high percentage (a read 1/3 of the population) might be infected with toxoplasmosis, only very view actually develop any symptoms. Those that do are mostly people with a compromised immune system and pregnant women. Actually, I remember that for decades pregnant women are advised to stay away from cats because of that.
        I read about the possible subtle influence the parasite can have on our behavior, however, something like increased risk taking or higher probability for car accidents seems difficult to validate in my opinion, so I'm rather doubtful about those claims. For example, how do you know that if a person exhibits schizophrenia it is caused by toxoplasmosis ? Unless you run a study comparing the same person with and without the parasite, you can't know whether or not it is the real cause.
        Schizophrenia certainly is a disease, It's a mental disorder and can be found as such in the DSM-V.
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        Dec 20 2013: Pabrita, 12 out of 44 had reduced grey matter. This means, 32 that also had schizophrenia neither had a reduction in grey matter nor did they have a T. gondii infection.
        First the sample size is terribly small to be of much value. Secondly, more people without T. gondii had schizophrenia.
        Frankly, how can one conclude based on this information that schizophrenia is related to a T. gondiii infection ?
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        Dec 21 2013: Pabitra, none of those links provides details about the methodology,
        In any case, if infections with toxoplasmosis are so prevalent (at least 30 % of the population) it's virtually impossible not to find people that have toxoplasmosis AND some mental issue.
        The question is how do you establish causality ? In other words how does one know that toxoplasmosis was the cause for the mental issue
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          Dec 22 2013: Well the surest way is to have a test for T.Gondii, it may be available in few countries. Jaroslav himself got himself checked and tested positive.
          It is a problem to determine how much the parasite is controlling the brain, but please note that the debate is about how much not anymore about whether. Schizophrenia can be caused for various reasons, not all very well known, T. Gondii adds to the list.
          I am sure with research the causality will be established, if not the idea will be scrapped. When I read your responses, I notice nothing unusual actually. Not even scientists like the idea that a single cell protozoan can take control of one's mind and behavior in a subtle way. But Flegr's work, unfortunately, indicates towards that direction.
          Flegr is working on this for many years. When asked why his idea didn't become mainstream sooner, he says that its because he is not very outgoing, a recluse really, and he is not so proficient in English - those may be the reasons.
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        Dec 24 2013: Pabrita, since we cannot run human trials we can't establish causality in the case of Toxoplasmosis being responsible for schizophrenia, especially with such small sample sizes of the population.
        This whole story reminds of the Wakefield scam where he claimed that the MMR vaccine was responsible for autism. This claim was eventually disproved. Wakefileld either disseminated false data on purpose or he fell victim to the causality fallacy assuming that because the appearance of autism coincided with the vaccination the vaccination must be the culprit.
        This Toxoplasmosis story sounds very similar to the MMR story.