The Nature V. Nurture False Dichotomy
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Hi allAs you know by now, I am fascinated by human behaviour and have quite an interest in genetics. You should also know that I am not a “genetic determinist”. I have to state this more or less each time I make a contribution; such is the “blank slate” theory of human behaviour still in vogue within the SP, and the consequent assumption that anyone who mentions genes and behaviour in the same sentence, must be a “genetic determinist”.My position is that “genes matter”, and so does the environment. You cannot separate the two.The condition I would like to share with you today is an interesting one, and one that I have meant to mention before in our exchanges, but I forgot to do so.Not only do human genes have an effect on human behaviour, but so, possibly, do the genes of a parasite: “Toxoplasma gondii”. Apparently, latent infection with Toxoplasma gondii, a common protozoan parasite, is among the most prevalent of human infections.The normal target hosts for this parasite are cats, via rodents. When infected, the behaviour of the rodents changes so that instead of being frightened of cats, they start behaving in a devil-may-care way, take risks, and are thus more likely to be caught by cats (inside which the parasite completes its life cycle).A common way for humans to ingest the parasite is if they have been in contact with cat faeces. According to Wikipedia, “In the United States about 23% are affected and in some areas of the world this is up to 95%.”Studies have shown that humans infected by the parasite show small, but statistically significant, behavioural changes with some differences in the way men and women are affected. More research is needed to determine if the effect on human behaviour is a direct result of the presence of the parasite, or of the human body’s immune response – or, indeed, if people already having the behavioural characteristics are more likely to own cats (for example).
Quote:“For the first time, we’ve shown that such parasite manipulation occurs in a primate, in a very specific way. We found that in our closest relative, the chimpanzee, Toxoplasma-infected animals lost their innate aversion towards leopard urine, their only natural predator,” she added.It had been thought that if Toxoplasma, a single-cell “protozoan” parasite similar to malaria, does have an effect on human behaviour it must be a side-effect of its ability to manipulate the behaviour of other “dead end” host species such as rodents. However, the discovery that it can affect other primate species suggests a more ancient evolutionary link with humans, Dr Poirotte said.“Our study rather supports the hypothesis that manipulative abilities of T. gondii have evolved in the human lineage when our ancestors were still under feline predation. Behavioural modifications in humans could thus be an ancestral legacy of our evolutionary past,” she said.“Latent toxoplasmosis was commonly assumed to be asymptomatic in humans, except in pregnant women….Recent studies have shown that it could represent a risk factor for some mental disease such as schizophrenia, but more studies are needed to understand all the impacts on human health,” she added. http://www.independent.co.uk/news/science/toxoplasma-gondii-parasite-that-breeds-in-cats-could-affect-human-behaviour-when-it-infects-people-a6861221.htmlI will leave it to those that are interested to do their own research on the internet and elsewhere.But I think this could be quite a good example of what Richard Dawkins called “the extended phenotype”; i.e., an organism’s genes reaching beyond its own body to influence other organisms.One example Dawkins gave of this was a male song bird’s genes, honed by evolution in such a way that they produce sound that travels through the air until they hit the auriculars (ears) of the female bird who, impressed by the beautiful song, cannot help herself but is drawn in his direction.Meel
Meel wrote:As you know by now, I am fascinated by human behaviour and have quite an interest in genetics. You should also know that I am not a “genetic determinist”. I have to state this more or less each time I make a contribution; such is the “blank slate” theory of human behaviour still in vogue within the SP, and the consequent assumption that anyone who mentions genes and behaviour in the same sentence, must be a “genetic determinist”.Not true, the so-called "blank slate" theory is not in vogue in the Socialist Party. See for instance the review of Steven Pinker's The Blank Slate: The Modern Denail of Human Natrure in the April 2003 Socialist Standard (here) and in particular this passage:
Quote:We are not required to defend everything that Marx or the Cultural Anthropologists said or did. However, neither thought that the mind had no structure or that there was no such thing as human nature. Both Marx and the Cultural Anthropologists rejected Blank Slatism for one of the reasons Pinker advances for knocking down his straw man who believes in it: “That the mind can't be a blank slate, because blank slates don't do anything”. Precisely. The brain is not just a passive receptor of sense-impressions (experience) but plays an active role in organising these impressions so as to make sense of them (understand them). This capacity to organise sense-impressions is part of human biological nature. Clearly, before humans could develop culture – “accumulated local wisdom: ways of fashioning artifacts, selecting food, dividing up windfalls, and so on”, as Pinker defines it, which is learned and passed on by non-biological means – they had to have brains capable of learning and of using language and of thinking abstractly with symbols representing parts of the outside world. These brains had to have evolved and are just as much a part of “human nature” as walking upright and stereoscopic colour vision. So, there's no denial of human nature here.As to not wanting to mention genes, we have published a whole pamphlet on the question, Are We Prisoners of Our Genes?, which can be found here.Dawkins's “extended phenotype” is him backtracking on some of the more extravagant claims he made in his original "selfish gene" book.
Quote:ALB Wrote:Not true, the so-called "blank slate" theory is not in vogue in the Socialist Party. See for instance the review of Steven Pinker's The Blank Slate: The Modern Denail of Human Natrure in the April 2003 Socialist Standard (here) and in particular this passage:I would be delighted to think that the “blank slate” is not supported by the SP. The link you provide above is interesting and nuanced.However, I get mixed messages reading contributions on your forum. For example, when I see claims that “human behaviour is culturally determined”, without further qualifications, this to me seems to suggest that this is precisely what you propose, an “infinitely malleable” human nature at birth, inscribed by “culture”.In any case, were you not at least a bit intrigued by the life cycle of the Toxoplasma parasite and its ability to change not just the behaviour of rodents, but ours as well? This was the interesting bit of information I wanted to convey.Meel
there is another toxoplasmosis on youtube. https://www.youtube.com/watch?v=XuKjBIBBAL8
Hi DaveYes, I have seen this before. Scary stuff. I think of this kind of thing when the Jehovah’s Witness I work with waxes lyrical about "the beauty of God's creation", and "isn't it perfect in every way".There are some very interesting articles about on viruses and bacteria and how they can alter the host's behaviour (including the human host).Meel
I see from the papers that it's the 40th anniversary of Dawkins's book The Selfish Gene and that they're bringing out a special anniversary edition of it. It's a terrible book. Even its basic scientific hypothesis (that the unit of biological evolution is the individual gene) has been open to challenge (look at the convolutions its supporters have to go through to explain "altruism" and the survival of females after they can no longer have offspring), but worse is the title which suggests (and was probably meant to suggest by the publishers, if not by Dawkins himself)and which successfully cashed in on the popular and populist illusion that humans are genetically selfish. Ok, Dawkins later recognised that he'd gone too far and he backtracked in the books he wrote after by introducing "extended phenotypes", grouped genes, "memes", etc.Having said that, his The Blind Watchmaker (also being repiblished) is a good popular science book explaining evolution. He's also done some other good work defending rationalism against religion and pseudi-science. Even so, The God Illusion (which is being republished too) suffers from being a purely rationalist criticism of religion that doesn't take into account the sociological reasons for its coming into being and continued existence.
I don't know whether there's anything in this or not but at least it's a contribution to the debate:http://socialismoryourmoneyback.blogspot.co.uk/2016/05/poverty-is-genetically-damaging.html
I think we did epigenetics on this forum not all that long ago. An analysis of the general 19thcentury debate is a bit problematic due to the inevitable inclusion and transference of 20thcentury and thus anachronistic DNA gene theory back into it. The ‘content’ of Lamarkism is; …the ideathat an organismcan pass on characteristics that it has acquired during its lifetime to its offspring… The content of modern Epigentics, or the form it takes now is; ….Epigenetics is the study, in the field of genetics, of cellular and physiological phenotypic trait variations that are caused by external or environmental factors that switch genes on and off and affect how cells read genes… It is splitting hairs a bit I think to say that these two idea are irreconcilable or don’t share a common thread, root or content. There is a false and anachronistic idea, based on pedantry, put that Darwin ‘radically’ overturned Lamarkism. Whilst Darwin had his own speculative version or form of lamarkism and epigenetics which he so happened to call a ‘pangenesis theory’. Thus; …Darwin's pangenesis theory was criticised for its Lamarckian premise that parents could pass on traits acquiredin their lifetime…. https://en.wikipedia.org/wiki/Pangenesis So to cut the crap and debate the matter as it stands now. The environment ‘affects’ the genes of an organism ‘that are already there’; and an organism somehow, by some feedback system, can activate or reactivate or switch on genetic instructions from its library and switch off others. Actually this modern idea is much more radical and sensational than boring Engels like Lamarkism. I mean it is ‘bad enough’ that using my thumb alot would make me have children with good thumbs; but it is even ‘worse’, surely? that I could genetically and phenotypically develop a better thumb in a lifetime. You would think it was a less radical idea that we inherit our own genes in various states of switched on or off-ness? This was first allegedly noticed quite recently in microbes as you might expect in fast breeders. Where they seemed to develop fantastic new and integrated metabolic tricks in a surprisingly short time. i was up to speed anyway as i discussed that with bob malone on the old forum 10 years ago. In a way you could think of it is a kind of ironic fillip to the ensemble of social relations theory. star trek did a variation of it as well. https://en.wikipedia.org/wiki/Genesis_(Star_Trek:_The_Next_Generation)
ALB wrote:I don't know whether there's anything in this or not but at least it's a contribution to the debate:http://socialismoryourmoneyback.blogspot.co.uk/2016/05/poverty-is-genetically-damaging.htmlInteresting how the geneticists are catching up with attachment theorists. However typically they fail to see the social context of the situation, early anxiety is not specifically about poverty but rather a function of the absence of what Ainsworth called the Secure Base. Bowlby's theory was based on how we learn to regulate and manage anxiety, the presence of a predictable and calm care giver is how infants and growing children learn to regulate their anxiety. Quite obviously poverty and social depravation can cause more distraction and unavailability in care givers (usually parents however this is not always the case, writers have recently started describing "boarding school syndrome" amongst those educated from an early age, including those who have had multiple care givers in their early but privileged lives (different au pairs every week, parents too busy to bother etc.).If the secure base is not available then the limbic system is over stimulated. In the case of children who suffer early years abuse, neglect and privation, the impact has been known and understood for decades, hype vigilance, social anxiety and in extreme cases Borderline Personality disorder, Psychopathy, etc. They seem to be mistaking the social effect for the genetic impact!
ALB wrote
Quote:I don't know whether there's anything in this or not but at least it's a contribution to the debate:http://socialismoryourmoneyback.blogspot.co.uk/2016/05/poverty-is-geneti…I think this blog is relevant to the discussion. The two examples of famines altering the genes of future generations that I have come across are “the Dutch Hunger Winter” and a Swedish famine of 1836.I recently read Nessa Carey’s “The Epigenetics Revolution”, which mentions this Dutch famine. Below is link to a fair review of her book (my emphasis in the extract):
Quote:The glorification of individual scientists in the popular science trade is often coupled with a desire to give individualized illustrations of general points. In The Epigenetics Revolution the exemplar is the movie star Audrey Hepburn. As a child (Figure 3) Hepburn lived through the privations of the Dutch Hunger Winter, when a German blockade led to famine conditions in parts of Holland. Studies based on people in utero during this catastrophe have suggested long-term influences on adult disease risk, and some transgenerational influences on their reproductive outcomes have been reported. For Audrey Hepburn, who was a teenager during the hunger winter, we are told that ‘the after effects of this period, including poor physical health, stayed with her for the rest of her life’. This story was picked up by the British Daily Mail newspaper in a review of the book entitled ‘Is Audrey Hepburn the key to stopping the obesity epidemic?’.8 The answer is, of course, no. The Dutch Hunger Winter literature and theorizing regarding the supposed epigenetic influences of this event are largely based on those exposed in utero; Hepburn was a teenager.http://ije.oxfordjournals.org/content/41/1/303.full The epigenetic “control mechanism” (controlling the on/off switch on genes, and the level at which they are expressed) is usually wiped clean between generations, but not always it appears.Below from an article about the Swedish famine:
Quote:In the second prong, the researchers expanded the Överkalix data to include both men and women from multiple birth years, and what they saw was remarkable. As before, the grandsons of men who had a season of feast just before puberty were at significantly increased risk of earlier death. But they also found that the granddaughters of women who had lived through a famine period when they were in the womb or just born were also at significantly increased risk of early death. In other words, grandfathers who were over-nourished when their sperm were forming put their grandsons at risk of early death, and grandmothers who were undernourished in the womb—when their eggs were forming—put their granddaughters at risk. But how could the non-genetic message be getting passed down?Bygren and Pembrey proposed that epigenetic mechanisms were at work. Epigenetics, which means, literally, “above genes,” describes how genes are turned on and off by certain molecules that attach to them—called epigenetic marks. The marks essentially act like on/off switches for genes. The cells that make up your brain and your muscles all have the same DNA at their center, and yet the reason the cells lead entirely different lives involves how epigenetic marks turn on or off particular genes, giving the cells their own unique identities. That was known well prior to Bygren and Pembrey’s work. The stunning implication of the ALSPAC smoking data and the Överkalix data was that some important epigenetic marks that impact human health might not get wiped clear between generations, but might actually be passed down for multiple generations along with genes. Bygren finally published his initial Överkalix data in 2001, and he and Pembrey published their joint work in 2006, in the European Journal of Human Genetics. Meanwhile, transgenerational epigenetic inheritance was being definitively demonstrated in animals.http://io9.gizmodo.com/how-an-1836-famine-altered-the-genes-of-children-born-d-1200001177Epigenetics is one interesting extension to the traditional, vertical neo-Darwinist/modern synthesis view of evolution by natural selection.
I think things have been moving on quite fast re ‘epigenetics’ over the last 15 years. It cautiously and heretically stuck its head above the parapet as I said, recently, circa 15 years ago, in the relatively safe area of microbes. But it then steered well clear of behaviour in higher animals. Some recent research has been done on rat behaviour. So they have one set of male rats or whatever in a horrid stressed environment or whatever, and another set who have access to Sky rat porn TV, season tickets for Newcastle United Games and lots of food and Brown Ale etc. Male rats is important here. Because they wank them both off and take the sperm and inseminate a control group of just general female rats, like you do. Then they compare the ‘behaviour’ of the progeny of the male stressed rats to that of the male happy rats. The attraction of this experiment is that there would appear to be no possibility of a contactless isolated wanked off male rats, happy or not, passing on a cultural essembly of social relations from the father to son etc. But what appeared to happen, and it was apparently sensationally experimentally reproduced, was that the stressed male parent rats ‘produced’ , subjectively, ‘neurotic psychopathic offspring’. Whilst the other lot were chilled out rat like hippies in comparison.
Contrary to your hypothesis, Newcastle United Season tickets actually create horrid stressed environments, believe me I know, I'm just off to measure my sperm
I would have thought that epigenetics, in showing that how some genes have their effect on the body is influenced by the environment, undermines the genetic determinists' case that we are the prisoners of our genes. This was obvious anyway but the scientists working in the field of epigenetics seem to be coming up with the way this works.
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