7 ms·

Evolution could explain the placebo effect

43 points by mmahemoff 14y ago

lukevdp 14y ago
"Evolution could explain the placebo effect" Umm... what else could explain the placebo effect? Evolution can explain every biological aspect ever to have existed if you take it to a broad enough level
- aufreak3 14y ago
  It is healthy to be wary of "evolution explains X" claims. As you say, evolution theory is intended to explain all biological developments. That doesn't mean that any particular evolutionary pressure we can conceive of that logically leads to the effect is the real explanation.
  - dllthomas 14y ago
    Yes, but the headline is still funny. "Evolution could explain the placebo effect" is a fantastic understatement - evolution almost certainly explains the placebo effect. "We could have found the evolutionary explanation for the placebo effect" is less snappy, though, I guess.
- mindslight 14y ago
  Methinks you need to refine your definition of 'explain'.
- drcube 14y ago
  Not really. Evolution only explains the persistence of traits which influence survival and reproduction. It can't explain why those traits arose in the first place (random mutation), or the existence of traits which don't affect survival or reproduction. It also can't explain why some traits never arose at all (say, winged humans). And to be really nitpicky, "evolution" is the observed fact that species change over time. It isn't an explanation at all. Natural selection is the explanation for evolution, both in general, and for specific traits.
  - sageikosa 14y ago
    Random mutation and natural selection. One's a generator, the other a filter.
- nyan_sandwich 14y ago
  In the same sense that Physics can explain it... It might be better to refer directly to psychology and neuroscience to explain the placebo effect
tokenadult 14y ago
Because the submitted article mentions the placebo effect, in the usual manner of popular articles, perhaps I should share here some links that are helpful for understanding what placebo effects are all about. Some of these online links cite quite a few useful scholarly publications. http://www.sciencebasedmedicine.org/index.php/michael-specter-on-the-placebo-effect/ http://www.sciencebasedmedicine.org/index.php/michael-specte... "In other words, the best research we have strongly suggests that placebo effects are illusions, not real physiological effects. The possible exception to this are the subjective symptoms of pain and nausea, where the placebo effects are highly variable and may be due to subjective reporting." http://www.sciencebasedmedicine.org/index.php/angells-review-of-psychiatry/ http://www.sciencebasedmedicine.org/index.php/angells-review... http://theness.com/neurologicablog/index.php/the-rise-and-fall-of-placebo-medicine/ http://theness.com/neurologicablog/index.php/the-rise-and-fa... http://www.sciencebasedmedicine.org/index.php/placebo-effects-revisited/ http://www.sciencebasedmedicine.org/index.php/placebo-effect... http://www.skepdic.com/placebo.html http://www.skepdic.com/placebo.html http://www.sciencebasedmedicine.org/index.php/revisiting-daniel-moerman-and-placebo-effects/ http://www.sciencebasedmedicine.org/index.php/revisiting-dan... The statement in the article kindly submitted here, "Someone suffering from a low-level infection will recover just as nicely whether they take an active drug or a simple sugar pill" should be interpreted as "Animals have a lot of capacity for recovering from infections, and some treatments for infections are indistinguishable in outcomes from doing nothing" until a citation for a specific study involving infection in HUMAN subjects is brought into the discussion. Usually the "placebo effect" is just the no-op effect of the body healing over time with the body's own healing mechanisms, and the ONLY reliable findings of placebo effects in human medicine, according to the sources I am citing here, are self-reported subjective symptoms like pain and discomfort, not physiologically verifiable improvement in disease states. So let's not rush too fast to assume an explanation for a phenomenon until the phenomenon is better defined. The submitted article goes on to discuss some animal studies related to seasonal patterns of light and darkness. These studies are related to the idea that the immune system is costly to maintain, drawing on many physiological resources of the living organism. That's a reasonably important point and is indeed the subject of much ongoing research. But human beings, with their very complicated behavior patterns for adaptation to many environments, probably have a system for regulating immune response that is harder to observe. I note for the record and for your reading enjoyment that the recent book he Folly of Fools: The Logic of Deceit and Self-Deception in Human Life by Robert Trivers http://www.amazon.com/The-Folly-Fools-Deceit-Self-Deception/dp/0465027555 http://www.amazon.com/The-Folly-Fools-Deceit-Self-Deception/... includes a chapter, with some citations to scientific studies, about immune system interaction with the brain suggesting a theory of self-deception in the aid of bodily healing, on evolutionary grounds. The whole book is interesting, and there is better established findings in it, so it is well worth a read whatever other science says about placebo effects.
vectorbunny 14y ago
From the Nicholas Humphrey paper cited in the post: "My view is this. The human capacity for responding to placebos is in fact not necessarily adaptive in its own right (indeed it can sometimes even be maladaptive). Instead, this capacity is an emergent property of something else that is genuinely adaptive: namely, a specially designed procedure for 'economic resource management' that is, I believe, one of the key features of the 'natural health-care service' which has evolved in ourselves and other animals to help us deal throughout our lives with repeated bouts of sickness, injury, and other threats to our well-being". in full here: http://www.humphrey.org.uk/papers/2002GreatExpectations.pdf http://www.humphrey.org.uk/papers/2002GreatExpectations.pdf
vannevar 14y ago
FTA: We subconsciously respond to treatment - even a sham one - because it comes with assurances that it will weaken the infection, allowing our immune response to succeed rapidly without straining the body's resources. I wonder if there isn't an alternative explanation, that the placebo effect may be an elaboration of the human social instinct. Consider how a control patient in a drug trial must feel when they are not given any treatment. Perhaps receiving the pill is an act of symbolic inclusion in the tribe that cues the immune system that the individual has a better outlook because they will be cared for by others.
- maratd 14y ago
  > I wonder if there isn't an alternative explanation, that the placebo effect may be an elaboration of the human social instinct. You read my mind. We're social animals. Hamsters may respond to sunlight, human beings respond to communal support. We have plentiful food stores when we are supported by our community and have none when we are abandoned. We're not hamsters. Somebody bothering to place you in a study, ask you dozens of questions, then give you medicine ... at no cost to you ... doesn't that scream social support?
  - SquareWheel 14y ago
    I wonder if a placebo would be just as effective if taken at home as a Tylenol or similar.
syncerr 14y ago
If we are to believe that triggering the full-force of the immune system is some sort of switch, then perhaps it would be possible to synthesize a drug to do this directly?
- TheSOB88 14y ago
  According to the article, that drug is sugar in a gelcap...
username3 14y ago
What can't evolution explain?
- SquareWheel 14y ago
  Well, abiogenesis, for one.
jeffdavis 14y ago
"I'm pleased to see that my theory stands up to computational modelling," Was anyone else disturbed by that statement? We all know that models are heavily dependent on parameters, and by tweaking them you can get whatever result you want. The only use a model has is when it shows a pattern of predicting observations in the real world. In other words, a model is essentially a theory about the way the world works. So "stands up to computational modeling" strikes me as a very unscientific thing to say -- kind of like saying "my theory stands up to his theory". Theories should stand up against testing and observations in the real world.
- aggronn 14y ago
  Without reading the context, I expect that 'computational modeling' refers to a largely mathematical model that is potentially agnostic about underlying causes. You can run simulations that accurately reflect the real world using one set of variables, then run another model (or somehow test another model) that confirms the original simulation's results from a different perspective; ie, you have two theories, and you validate the second by proving its equivalent to the first, even though it uses a different set of variables, or looks at it using a different theoretical framework. of course, you're right that this can be troublesome. just because you can validate a theory as accurately modeling reality doesn't mean that the components of the model are true or useful. and necessarily, the first 'computational model' would have needed to be already validated before something else might be validated against it...in case that wasn't clear.

43 points by mmahemoff 14y ago

"Evolution could explain the placebo effect" Umm... what else could explain the placebo effect? Evolution can explain every biological aspect ever to have existed if you take it to a broad enough level

aufreak3 14y ago
It is healthy to be wary of "evolution explains X" claims. As you say, evolution theory is intended to explain all biological developments. That doesn't mean that any particular evolutionary pressure we can conceive of that logically leads to the effect is the real explanation.
- dllthomas 14y ago
  Yes, but the headline is still funny. "Evolution could explain the placebo effect" is a fantastic understatement - evolution almost certainly explains the placebo effect. "We could have found the evolutionary explanation for the placebo effect" is less snappy, though, I guess.
mindslight 14y ago
Methinks you need to refine your definition of 'explain'.
drcube 14y ago
Not really. Evolution only explains the persistence of traits which influence survival and reproduction. It can't explain why those traits arose in the first place (random mutation), or the existence of traits which don't affect survival or reproduction. It also can't explain why some traits never arose at all (say, winged humans). And to be really nitpicky, "evolution" is the observed fact that species change over time. It isn't an explanation at all. Natural selection is the explanation for evolution, both in general, and for specific traits.
- sageikosa 14y ago
  Random mutation and natural selection. One's a generator, the other a filter.
nyan_sandwich 14y ago
In the same sense that Physics can explain it... It might be better to refer directly to psychology and neuroscience to explain the placebo effect

tokenadult 14y ago

Because the submitted article mentions the placebo effect, in the usual manner of popular articles, perhaps I should share here some links that are helpful for understanding what placebo effects are all about. Some of these online links cite quite a few useful scholarly publications. http://www.sciencebasedmedicine.org/index.php/michael-specter-on-the-placebo-effect/ http://www.sciencebasedmedicine.org/index.php/michael-specte... "In other words, the best research we have strongly suggests that placebo effects are illusions, not real physiological effects. The possible exception to this are the subjective symptoms of pain and nausea, where the placebo effects are highly variable and may be due to subjective reporting." http://www.sciencebasedmedicine.org/index.php/angells-review-of-psychiatry/ http://www.sciencebasedmedicine.org/index.php/angells-review... http://theness.com/neurologicablog/index.php/the-rise-and-fall-of-placebo-medicine/ http://theness.com/neurologicablog/index.php/the-rise-and-fa... http://www.sciencebasedmedicine.org/index.php/placebo-effects-revisited/ http://www.sciencebasedmedicine.org/index.php/placebo-effect... http://www.skepdic.com/placebo.html http://www.skepdic.com/placebo.html http://www.sciencebasedmedicine.org/index.php/revisiting-daniel-moerman-and-placebo-effects/ http://www.sciencebasedmedicine.org/index.php/revisiting-dan... The statement in the article kindly submitted here, "Someone suffering from a low-level infection will recover just as nicely whether they take an active drug or a simple sugar pill" should be interpreted as "Animals have a lot of capacity for recovering from infections, and some treatments for infections are indistinguishable in outcomes from doing nothing" until a citation for a specific study involving infection in HUMAN subjects is brought into the discussion. Usually the "placebo effect" is just the no-op effect of the body healing over time with the body's own healing mechanisms, and the ONLY reliable findings of placebo effects in human medicine, according to the sources I am citing here, are self-reported subjective symptoms like pain and discomfort, not physiologically verifiable improvement in disease states. So let's not rush too fast to assume an explanation for a phenomenon until the phenomenon is better defined. The submitted article goes on to discuss some animal studies related to seasonal patterns of light and darkness. These studies are related to the idea that the immune system is costly to maintain, drawing on many physiological resources of the living organism. That's a reasonably important point and is indeed the subject of much ongoing research. But human beings, with their very complicated behavior patterns for adaptation to many environments, probably have a system for regulating immune response that is harder to observe. I note for the record and for your reading enjoyment that the recent book he Folly of Fools: The Logic of Deceit and Self-Deception in Human Life by Robert Trivers http://www.amazon.com/The-Folly-Fools-Deceit-Self-Deception/dp/0465027555 http://www.amazon.com/The-Folly-Fools-Deceit-Self-Deception/... includes a chapter, with some citations to scientific studies, about immune system interaction with the brain suggesting a theory of self-deception in the aid of bodily healing, on evolutionary grounds. The whole book is interesting, and there is better established findings in it, so it is well worth a read whatever other science says about placebo effects.

vectorbunny 14y ago

From the Nicholas Humphrey paper cited in the post: "My view is this. The human capacity for responding to placebos is in fact not necessarily adaptive in its own right (indeed it can sometimes even be maladaptive). Instead, this capacity is an emergent property of something else that is genuinely adaptive: namely, a specially designed procedure for 'economic resource management' that is, I believe, one of the key features of the 'natural health-care service' which has evolved in ourselves and other animals to help us deal throughout our lives with repeated bouts of sickness, injury, and other threats to our well-being". in full here: http://www.humphrey.org.uk/papers/2002GreatExpectations.pdf http://www.humphrey.org.uk/papers/2002GreatExpectations.pdf

vannevar 14y ago

FTA: We subconsciously respond to treatment - even a sham one - because it comes with assurances that it will weaken the infection, allowing our immune response to succeed rapidly without straining the body's resources. I wonder if there isn't an alternative explanation, that the placebo effect may be an elaboration of the human social instinct. Consider how a control patient in a drug trial must feel when they are not given any treatment. Perhaps receiving the pill is an act of symbolic inclusion in the tribe that cues the immune system that the individual has a better outlook because they will be cared for by others.

maratd 14y ago
> I wonder if there isn't an alternative explanation, that the placebo effect may be an elaboration of the human social instinct. You read my mind. We're social animals. Hamsters may respond to sunlight, human beings respond to communal support. We have plentiful food stores when we are supported by our community and have none when we are abandoned. We're not hamsters. Somebody bothering to place you in a study, ask you dozens of questions, then give you medicine ... at no cost to you ... doesn't that scream social support?
- SquareWheel 14y ago
  I wonder if a placebo would be just as effective if taken at home as a Tylenol or similar.

syncerr 14y ago

If we are to believe that triggering the full-force of the immune system is some sort of switch, then perhaps it would be possible to synthesize a drug to do this directly?

TheSOB88 14y ago
According to the article, that drug is sugar in a gelcap...

username3 14y ago

What can't evolution explain?

SquareWheel 14y ago
Well, abiogenesis, for one.

jeffdavis 14y ago

"I'm pleased to see that my theory stands up to computational modelling," Was anyone else disturbed by that statement? We all know that models are heavily dependent on parameters, and by tweaking them you can get whatever result you want. The only use a model has is when it shows a pattern of predicting observations in the real world. In other words, a model is essentially a theory about the way the world works. So "stands up to computational modeling" strikes me as a very unscientific thing to say -- kind of like saying "my theory stands up to his theory". Theories should stand up against testing and observations in the real world.

aggronn 14y ago
Without reading the context, I expect that 'computational modeling' refers to a largely mathematical model that is potentially agnostic about underlying causes. You can run simulations that accurately reflect the real world using one set of variables, then run another model (or somehow test another model) that confirms the original simulation's results from a different perspective; ie, you have two theories, and you validate the second by proving its equivalent to the first, even though it uses a different set of variables, or looks at it using a different theoretical framework. of course, you're right that this can be troublesome. just because you can validate a theory as accurately modeling reality doesn't mean that the components of the model are true or useful. and necessarily, the first 'computational model' would have needed to be already validated before something else might be validated against it...in case that wasn't clear.