zz有诱人的证据表明一种普通的寄生虫可能影响人类的行为
http://article.yeeyan.org/view/108624/109261
弓形虫病与心理学
A game of cat and mouse
猫鼠游戏的背后
There is tantalising evidence that a common parasite may affect human behaviour
有诱人的证据表明一种普通的寄生虫可能影响人类的行为
Jun 3rd 2010 | From The Economist print edition
2010年6月3日|《经济学人》印刷版
IF AN alien bug invaded the brains of half the population, hijacked their neurochemistry, altered the way they acted and drove some of them crazy, then you might expect a few excitable headlines to appear in the press. Yet something disturbingly like this may actually be happening without the world noticing.
假如有一种外星虫子入侵半数人的大脑，并劫持他们的神经系统，改变他们的行为方式，使之陷入疯狂，那么你很快就会在各大新闻报纸的头条读到相关的报道。然而，有些类似的事情可能正在发生，却并没引起世界的关注。
Toxoplasma gondii is not an alien; it is a relative of that down-to-earth pathogen Plasmodium, the beast that causes malaria. It is common: in some parts of the world as much as 60% of the population is infected with it. And it can harm fetuses and people with AIDS, because in each case their immune systems cannot cope with it. For other people, though, the symptoms are usually no worse than a mild dose of flu. Not much for them to worry about, then. Except that there is a growing body of evidence that some of those people have their behaviour permanently changed.
冈地弓形虫并不是外来生物，它与导致疟疾的疟原虫是近亲：在世界上某些地区差不多有60%的人口感染这种寄生虫。它会对婴儿和艾滋病患者造成危害，因为这些人的免疫力比较低，不足以应付它们。不过对其它多数人来说，感染这种寄生虫的症状通常类似于一场轻微的感冒，并没有什么好担心的。除非有越来越多的证据表明，感染人群中有部分人的行为方式发生永久性的改变。
One reason to suspect this is that a country’s level of Toxoplasma infection seems to be related to the level of neuroticism displayed by its population. Another is that those infected seem to have poor reaction times and are more likely to be involved in road accidents. A third is that they have short attention spans and little interest in seeking out novelty. A fourth, possibly the most worrying, is that those who suffer from schizophrenia are more likely than those who do not to have been exposed to Toxoplasma.
产生这种怀疑的原因有四个：其一，某个国家感染弓形虫的水平好像与该国民众的神经质水平密切相关；其二，感染人群可能反应迟缓[注1]，更容易发生交通事故；其三，他们注意力不够集中，对新鲜事物缺乏好奇心；其四，也是最令人担忧的，精神分裂症患者感染弓形虫的比率要比其它人高的多。
Nor is any of this truly surprising. For, besides humans, Toxoplasma has two normal hosts: rodents and cats. And what it does to rodents is very odd indeed.
以上这些原因还不算真正的奇怪。除了人类之外，弓形虫还有两种典型的寄主：啮齿动物和猫科动物。那些感染弓形虫的啮齿动物才真叫古怪。
Fatal feline attraction
猫的致命诱惑
Joanne Webster of Imperial College, London, has been studying Toxoplasma for years. Like Plasmodium, which cycles between mosquitoes and man, Toxoplasma cycles between its rodent and feline hosts, living out different phases of its existence in each. In cats, it resides in the wall of the small intestine and passes out of the host in its faeces. These are then picked up by rats and mice (and also by other mammal species, including humans), where they form cysts in brain, liver and muscle tissue. Eventually, if the parasites are lucky, their rodent host is eaten by a cat and the whole cycle starts again.
伦敦帝国大学的乔安妮·韦伯斯特（Joanne Webster ）从事弓形虫研究多年。与疟原虫在蚊子和人类之间循环传播类似，弓形虫的循环在它的寄主啮齿动物和猫科动物之间进行，它在不同的寄主身上以不同状态存在。它生活在猫的小肠壁上，随着寄主的粪便排出体外。然后，它们就会被老鼠染上（同时还有包括人类在内的其它哺乳动物），以胞囊的形式存在于大脑、肺和肌肉组织内。最终，那些幸运的寄生虫，它们的老鼠寄主会被一只猫逮住吃掉，新一轮的循环重新开始。
Unlike Plasmodium, however, which can rely on the natural behaviour of mosquitoes to spread it around, Toxoplasma’s rodent hosts have a strong aversion to helping it into its next home. Which is where, in Dr Webster’s elegant phrase, fatal feline attraction comes in. Rats and mice infected with Toxoplasma start wandering around and drawing attention to themselves—in other words, behaving in ways that will bring them to the attention of cats. They are even, Dr Webster’s work suggests, attracted to the smell of cats.
与疟原虫不同的是，疟原虫依靠蚊子的嗜血天性传播，然而弓形虫的老鼠寄主肯定不会心甘情愿地跑到猫肚子里去。在这种情况下，用韦伯斯特博士简洁的说法， “猫的致命诱惑”出现了。感染了弓形虫的老鼠开始四处闲逛，行为乖张，自我表现——也就是说，他们的行为方式让它们更加容易引起猫的注意。韦伯斯特的工作表明它们甚至会被猫的气味所吸引。
How these behavioural changes come about was, until recently, obscure. But in 2009 Glenn McConkey of the University of Leeds, in England, analysed Toxoplasma’s DNA. When he compared the results with those of other species, he discovered that two of the bug’s genes encode enzymes involved in the production of a molecule called dopamine. This molecule acts, in animals that have nervous systems, as a chemical messenger between nerve cells. It does not, however, have any known function in single-celled critters. Moreover, dopamine is particularly implicated in schizophrenia. Haloperidol, an antipsychotic drug, works by blocking dopamine receptors.
这些行为改变是如何产生的至今仍让人费解。但是，2009年，英格兰利德斯大学的格伦·麦肯基（Glenn McConkey ）分析了弓形虫的DNA。他把结果与其它物种比较发现弓形虫基因编码的两种酶与一种叫做多巴胺的分子的产生有关。在具有神经系统的动物体内，多巴胺充当神经细胞间的化学信使。然而，单细胞动物当然不会有神经系统，他们产生多巴胺分子有什么用还不清楚。此外，多巴胺与精神分裂症有关。氟哌丁苯是一种强安定药，它的作用机理就是阻断多巴胺的受体。
Intriguingly, Dr Webster has found that haloperidol serves to reverse fatal feline attraction in rats. This suggests the parasite is indeed interfering with the brain’s dopamine system—and thus that it might be doing the same thing in people. Dr McConkey is now making a version of Toxoplasma with the dopamine genes excised, to see if rats infected with this modified bug are protected from the fatal attraction.
Culture club
文化俱乐部
The evidence that human toxoplasmosis does more than appears at first sight is, it must be said, quite scattered. But it is intriguing and probably worth following up.
不得不说，人类感染弓形虫比乍看起来要多得多，其证据非常分散。但是它十分有趣值得追踪研究。
The connection with schizophrenia was originally suggested in the 1950s, but only really took off in 2003, when it was revived by Fuller Torrey of the Stanley Medical Research Institute, near Washington, DC. In collaboration with Bob Yolken of Johns Hopkins University, Dr Fuller discovered that people who suffer from schizophrenia are almost three times more likely than the general population to have antibodies to Toxoplasma.
弓形虫病与精神分裂的联系最初在上世纪50年代被发现，但是直到2003年才真正开始有所发展，华盛顿特区附近的斯坦利医药研究院的富勒·特里（Fuller Torrey ）使之重获新生。在同约翰·霍普金斯大学的鲍勃·约肯（Bob Yolken ）的合作中，富勒博士发现患精神分裂症人群有弓形虫抗体的可能性几乎是普通人群的3倍。
That does not, of course, prove Toxoplasma causes schizophrenia. As every science student is taught from the beginning, correlation is not causation. It could be that schizophrenics are more susceptible to the infection, or some third, as yet unidentified variable may be involved.
当然，这并不能证明弓形虫会导致精神分裂。就像理科学生在最开始学到的那样，有相互关系并一定就是因果关系。可能是精神分裂症更容易感染弓形虫，或者有未知的第三方因素牵涉其中。
Another interesting correlation has, though, been discovered by Jaroslav Flegr of Charles University in Prague. Dr Flegr has studied several aspects of the Toxoplasma question. In one case he looked at the infection rate of people involved in road accidents. Both drivers and pedestrians who had been in accidents were almost three times more likely to be infected than comparable individuals who had not been. Similar results have been found in Turkey, by Kor Yereli of Celal Bayar University, in Manisa. And Dr Flegr has found other abnormalities in infected people. These included reduced reaction times and shorter attention spans—both of which might help to explain the accident statistics—and a reduction in “novelty-seeking”.
不过，布拉格查尔斯大学的雅罗斯拉夫·弗莱格（Jaroslav Flegr ）发现了另一种有趣的相互关系。弗拉格博士研究过弓形虫问题的诸多方面。在一个案例中，他统计了涉及到交通事故的人群的弓形虫感染率。发生交通事故的人，无论是驾驶员还是行人，他们的弓形虫感染率是类似无事故的人3倍。在土耳其马尼萨， 杰拉勒巴亚尔大学的科尔·耶莱里（Kor Yereli ）也发现了相似的结果。弗莱格博士还发现了感染人群的其它反常状况，其中包括减少反应时[注2]和缩短注意力集中时间——这两项可以帮助解释上面的交通事故统计——还会降低对新奇事物的追寻。
This latter is curious. The sort of behaviour shown by rodents is, if anything, an increase in novelty-seeking. But the point is that novelty-seeking is controlled by nerve cells that respond to dopamine. Humans are dead-end hosts as far as Toxoplasma is concerned, so the exact effect will not have been honed by natural selection and may therefore be different from the one in animals that are actually useful to the parasite.
后者非常奇怪。在啮齿动物中表现出的此类行为更可能是增加对新奇事物的追求程度。但是其重点是追寻新奇事物是由对巴多胺作出反应的神经细胞控制的。对弓形虫来说，人类是一个没有出路的宿主，确切的影响不会是由自然选择产生的，因此可能与对寄生虫实际有益的宿主动物有所不同。
All of these suggested effects are obviously bad for the individuals involved, but some researchers go further and propose that entire societies are being altered by Toxoplasma. In 2006 Kevin Lafferty of the University of California, Santa Barbara, published a paper noting a correlation between levels of neuroticism established by national surveys in various countries and the level of Toxoplasma infection recorded in pregnant women (a group who are tested routinely). The places he looked at ranged from phlegmatic Britain, with a neuroticism score of -0.8 and a Toxoplasma infection rate of 6.6%, to hot-blooded France, which scored 1.8 and had an infection rate of 45%. Cross-Channel prejudices, then, may have an unexpected origin.
所有这些提到的影响明显对涉及其中的个体不利，但是有些研究者进一步提出整个社会都在被弓形虫改变。2006年加州大学圣巴巴拉分校的凯文·拉弗蒂（Kevin Lafferty ）发表了一篇论文，指出在多个国家已经证实的调查中国民神经质的水平与记录的怀孕妇女感染弓形虫（一类常规检查）的水平密切相关。他查阅了从英国到法国各个地方的数据，其中冷漠的英国人神经质等级分为-0.8，弓形虫感染率为6.6%，而热血浪漫的法国人则分别为1.8和45%。跨越海峡的成见可能源于这样一个意想不到的原因。
To repeat, correlation is not causation, and a lot more work would need to be done to prove the point. But it is just possible that a parasite’s desire to get eaten by a cat is shaping the cultures of the world.
最后再重复一遍，有关系并不一定就是因果关系，要证明其中的关系还有大量的工作要做。但是存在这样一种可能：弓形虫想要它的老鼠寄主被猫吃掉的愿望塑造了世界文化的格局。
[注1][注2]:原文分别是"poor reaction times "和"reduced reaction times" ,如果反应时缩短,应该反应更快,怎么会导致事故多发?不明白.
弓形虫病与心理学
A game of cat and mouse
猫鼠游戏的背后
There is tantalising evidence that a common parasite may affect human behaviour
有诱人的证据表明一种普通的寄生虫可能影响人类的行为
Jun 3rd 2010 | From The Economist print edition
2010年6月3日|《经济学人》印刷版
IF AN alien bug invaded the brains of half the population, hijacked their neurochemistry, altered the way they acted and drove some of them crazy, then you might expect a few excitable headlines to appear in the press. Yet something disturbingly like this may actually be happening without the world noticing.
假如有一种外星虫子入侵半数人的大脑，并劫持他们的神经系统，改变他们的行为方式，使之陷入疯狂，那么你很快就会在各大新闻报纸的头条读到相关的报道。然而，有些类似的事情可能正在发生，却并没引起世界的关注。
Toxoplasma gondii is not an alien; it is a relative of that down-to-earth pathogen Plasmodium, the beast that causes malaria. It is common: in some parts of the world as much as 60% of the population is infected with it. And it can harm fetuses and people with AIDS, because in each case their immune systems cannot cope with it. For other people, though, the symptoms are usually no worse than a mild dose of flu. Not much for them to worry about, then. Except that there is a growing body of evidence that some of those people have their behaviour permanently changed.
冈地弓形虫并不是外来生物，它与导致疟疾的疟原虫是近亲：在世界上某些地区差不多有60%的人口感染这种寄生虫。它会对婴儿和艾滋病患者造成危害，因为这些人的免疫力比较低，不足以应付它们。不过对其它多数人来说，感染这种寄生虫的症状通常类似于一场轻微的感冒，并没有什么好担心的。除非有越来越多的证据表明，感染人群中有部分人的行为方式发生永久性的改变。
One reason to suspect this is that a country’s level of Toxoplasma infection seems to be related to the level of neuroticism displayed by its population. Another is that those infected seem to have poor reaction times and are more likely to be involved in road accidents. A third is that they have short attention spans and little interest in seeking out novelty. A fourth, possibly the most worrying, is that those who suffer from schizophrenia are more likely than those who do not to have been exposed to Toxoplasma.
产生这种怀疑的原因有四个：其一，某个国家感染弓形虫的水平好像与该国民众的神经质水平密切相关；其二，感染人群可能反应迟缓[注1]，更容易发生交通事故；其三，他们注意力不够集中，对新鲜事物缺乏好奇心；其四，也是最令人担忧的，精神分裂症患者感染弓形虫的比率要比其它人高的多。
Nor is any of this truly surprising. For, besides humans, Toxoplasma has two normal hosts: rodents and cats. And what it does to rodents is very odd indeed.
以上这些原因还不算真正的奇怪。除了人类之外，弓形虫还有两种典型的寄主：啮齿动物和猫科动物。那些感染弓形虫的啮齿动物才真叫古怪。
Fatal feline attraction
猫的致命诱惑
Joanne Webster of Imperial College, London, has been studying Toxoplasma for years. Like Plasmodium, which cycles between mosquitoes and man, Toxoplasma cycles between its rodent and feline hosts, living out different phases of its existence in each. In cats, it resides in the wall of the small intestine and passes out of the host in its faeces. These are then picked up by rats and mice (and also by other mammal species, including humans), where they form cysts in brain, liver and muscle tissue. Eventually, if the parasites are lucky, their rodent host is eaten by a cat and the whole cycle starts again.
伦敦帝国大学的乔安妮·韦伯斯特（Joanne Webster ）从事弓形虫研究多年。与疟原虫在蚊子和人类之间循环传播类似，弓形虫的循环在它的寄主啮齿动物和猫科动物之间进行，它在不同的寄主身上以不同状态存在。它生活在猫的小肠壁上，随着寄主的粪便排出体外。然后，它们就会被老鼠染上（同时还有包括人类在内的其它哺乳动物），以胞囊的形式存在于大脑、肺和肌肉组织内。最终，那些幸运的寄生虫，它们的老鼠寄主会被一只猫逮住吃掉，新一轮的循环重新开始。
Unlike Plasmodium, however, which can rely on the natural behaviour of mosquitoes to spread it around, Toxoplasma’s rodent hosts have a strong aversion to helping it into its next home. Which is where, in Dr Webster’s elegant phrase, fatal feline attraction comes in. Rats and mice infected with Toxoplasma start wandering around and drawing attention to themselves—in other words, behaving in ways that will bring them to the attention of cats. They are even, Dr Webster’s work suggests, attracted to the smell of cats.
与疟原虫不同的是，疟原虫依靠蚊子的嗜血天性传播，然而弓形虫的老鼠寄主肯定不会心甘情愿地跑到猫肚子里去。在这种情况下，用韦伯斯特博士简洁的说法， “猫的致命诱惑”出现了。感染了弓形虫的老鼠开始四处闲逛，行为乖张，自我表现——也就是说，他们的行为方式让它们更加容易引起猫的注意。韦伯斯特的工作表明它们甚至会被猫的气味所吸引。
How these behavioural changes come about was, until recently, obscure. But in 2009 Glenn McConkey of the University of Leeds, in England, analysed Toxoplasma’s DNA. When he compared the results with those of other species, he discovered that two of the bug’s genes encode enzymes involved in the production of a molecule called dopamine. This molecule acts, in animals that have nervous systems, as a chemical messenger between nerve cells. It does not, however, have any known function in single-celled critters. Moreover, dopamine is particularly implicated in schizophrenia. Haloperidol, an antipsychotic drug, works by blocking dopamine receptors.
这些行为改变是如何产生的至今仍让人费解。但是，2009年，英格兰利德斯大学的格伦·麦肯基（Glenn McConkey ）分析了弓形虫的DNA。他把结果与其它物种比较发现弓形虫基因编码的两种酶与一种叫做多巴胺的分子的产生有关。在具有神经系统的动物体内，多巴胺充当神经细胞间的化学信使。然而，单细胞动物当然不会有神经系统，他们产生多巴胺分子有什么用还不清楚。此外，多巴胺与精神分裂症有关。氟哌丁苯是一种强安定药，它的作用机理就是阻断多巴胺的受体。
Intriguingly, Dr Webster has found that haloperidol serves to reverse fatal feline attraction in rats. This suggests the parasite is indeed interfering with the brain’s dopamine system—and thus that it might be doing the same thing in people. Dr McConkey is now making a version of Toxoplasma with the dopamine genes excised, to see if rats infected with this modified bug are protected from the fatal attraction.
Culture club
文化俱乐部
The evidence that human toxoplasmosis does more than appears at first sight is, it must be said, quite scattered. But it is intriguing and probably worth following up.
不得不说，人类感染弓形虫比乍看起来要多得多，其证据非常分散。但是它十分有趣值得追踪研究。
The connection with schizophrenia was originally suggested in the 1950s, but only really took off in 2003, when it was revived by Fuller Torrey of the Stanley Medical Research Institute, near Washington, DC. In collaboration with Bob Yolken of Johns Hopkins University, Dr Fuller discovered that people who suffer from schizophrenia are almost three times more likely than the general population to have antibodies to Toxoplasma.
弓形虫病与精神分裂的联系最初在上世纪50年代被发现，但是直到2003年才真正开始有所发展，华盛顿特区附近的斯坦利医药研究院的富勒·特里（Fuller Torrey ）使之重获新生。在同约翰·霍普金斯大学的鲍勃·约肯（Bob Yolken ）的合作中，富勒博士发现患精神分裂症人群有弓形虫抗体的可能性几乎是普通人群的3倍。
That does not, of course, prove Toxoplasma causes schizophrenia. As every science student is taught from the beginning, correlation is not causation. It could be that schizophrenics are more susceptible to the infection, or some third, as yet unidentified variable may be involved.
当然，这并不能证明弓形虫会导致精神分裂。就像理科学生在最开始学到的那样，有相互关系并一定就是因果关系。可能是精神分裂症更容易感染弓形虫，或者有未知的第三方因素牵涉其中。
Another interesting correlation has, though, been discovered by Jaroslav Flegr of Charles University in Prague. Dr Flegr has studied several aspects of the Toxoplasma question. In one case he looked at the infection rate of people involved in road accidents. Both drivers and pedestrians who had been in accidents were almost three times more likely to be infected than comparable individuals who had not been. Similar results have been found in Turkey, by Kor Yereli of Celal Bayar University, in Manisa. And Dr Flegr has found other abnormalities in infected people. These included reduced reaction times and shorter attention spans—both of which might help to explain the accident statistics—and a reduction in “novelty-seeking”.
不过，布拉格查尔斯大学的雅罗斯拉夫·弗莱格（Jaroslav Flegr ）发现了另一种有趣的相互关系。弗拉格博士研究过弓形虫问题的诸多方面。在一个案例中，他统计了涉及到交通事故的人群的弓形虫感染率。发生交通事故的人，无论是驾驶员还是行人，他们的弓形虫感染率是类似无事故的人3倍。在土耳其马尼萨， 杰拉勒巴亚尔大学的科尔·耶莱里（Kor Yereli ）也发现了相似的结果。弗莱格博士还发现了感染人群的其它反常状况，其中包括减少反应时[注2]和缩短注意力集中时间——这两项可以帮助解释上面的交通事故统计——还会降低对新奇事物的追寻。
This latter is curious. The sort of behaviour shown by rodents is, if anything, an increase in novelty-seeking. But the point is that novelty-seeking is controlled by nerve cells that respond to dopamine. Humans are dead-end hosts as far as Toxoplasma is concerned, so the exact effect will not have been honed by natural selection and may therefore be different from the one in animals that are actually useful to the parasite.
后者非常奇怪。在啮齿动物中表现出的此类行为更可能是增加对新奇事物的追求程度。但是其重点是追寻新奇事物是由对巴多胺作出反应的神经细胞控制的。对弓形虫来说，人类是一个没有出路的宿主，确切的影响不会是由自然选择产生的，因此可能与对寄生虫实际有益的宿主动物有所不同。
All of these suggested effects are obviously bad for the individuals involved, but some researchers go further and propose that entire societies are being altered by Toxoplasma. In 2006 Kevin Lafferty of the University of California, Santa Barbara, published a paper noting a correlation between levels of neuroticism established by national surveys in various countries and the level of Toxoplasma infection recorded in pregnant women (a group who are tested routinely). The places he looked at ranged from phlegmatic Britain, with a neuroticism score of -0.8 and a Toxoplasma infection rate of 6.6%, to hot-blooded France, which scored 1.8 and had an infection rate of 45%. Cross-Channel prejudices, then, may have an unexpected origin.
所有这些提到的影响明显对涉及其中的个体不利，但是有些研究者进一步提出整个社会都在被弓形虫改变。2006年加州大学圣巴巴拉分校的凯文·拉弗蒂（Kevin Lafferty ）发表了一篇论文，指出在多个国家已经证实的调查中国民神经质的水平与记录的怀孕妇女感染弓形虫（一类常规检查）的水平密切相关。他查阅了从英国到法国各个地方的数据，其中冷漠的英国人神经质等级分为-0.8，弓形虫感染率为6.6%，而热血浪漫的法国人则分别为1.8和45%。跨越海峡的成见可能源于这样一个意想不到的原因。
To repeat, correlation is not causation, and a lot more work would need to be done to prove the point. But it is just possible that a parasite’s desire to get eaten by a cat is shaping the cultures of the world.
最后再重复一遍，有关系并不一定就是因果关系，要证明其中的关系还有大量的工作要做。但是存在这样一种可能：弓形虫想要它的老鼠寄主被猫吃掉的愿望塑造了世界文化的格局。
[注1][注2]:原文分别是"poor reaction times "和"reduced reaction times" ,如果反应时缩短,应该反应更快,怎么会导致事故多发?不明白.
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唐小糖@心理学是甜的 转发了这篇日记 2010-07-02 22:01:36 -
单刀刃 转发了这篇日记 2010-07-02 21:58:38
