My Contribution to the Science of Evolutionary Psychology

I may have actually helped create a new scientific theory today.

A couple months ago, I was thinking to myself about alternative medicine, after seeing a news report about one of the latest fad treatment for people who think actual medicine is too grounded in reality for their tiny minds to handle. This led to thoughts about the placebo effect, which is the only thing that makes most alternative medicine work at all. This in turn led to thoughts about how the heck something like the placebo effect could be produced by evolutionary pressures.

The real mystery about the placebo effect isn't the fact that sometimes the mere belief that a treatment works can lead to the body's own immune system and other defenses to cure an illness or reduce its symptoms faster than they otherwise would. The real mystery is: why the heck doesn't the body beat off illnesses that fast all the time? What possible evolutionary benefit could there be to a mechanism that slows down healing unless someone in a white lab coat hands you a pill and says it will cure you?

I actually came up with an idea. I couldn't remember hearing of this particular explanatory theory before, but I read a lot of odd scientific material now and then, and my memory is notoriously wonky when it comes to remembering if a joke is original or plagarized, so I wasn't sure if I'd really come up with an original concept or not. So for the last couple of days, I've been poking around on Google looking for anything online on the subject. I found several articles, most of which require a subscription to view, but of the free articles I found, one in particular seemed to be the sort of material I was looking for.

The article was"Great Expectations: The Evolutionary Psychology of Faith-Healing and the Placebo Effect", by Nicholas Humphrey of the London School of Economics. Dr. Humphrey focused on the costs and benefits to the sick individual of ramping up the immune system and other biological defense mechanisms, based on the situation in which one finds oneself injured or ill. Some responses to illness, such as fevers, can in some cases be more damaging then the illness itself, at least in the short term. The immune system is very expensive to operate in terms of energy, calories, and scarce nutrients such as carotinoids. In times of scarce food or other immediate danger, one may not have time to be bedridden, and thus it is better to simply let an infection run its course for a while, saving scarce resources for possible greater threats later on. Conversely, if one is safe at home and being taken care of by others, one may feel secure and confident enough to devote one's full biological resources to recovery.

However, my theory holds that the important thing, from an evolutionary standpoint, is the survival of the genes, not the survival of the individuals. At the time this placebo response mechanism evolved, humans lived in small groups of hunter-gatherers without modern medicine. These small bands were probably mostly composed of closely related family members (or relatives and potential relatives as future breeding creates genetic in-laws).

If an individual becomes sick or injured, his friends and family will likely try to nurse him through his illness in hopes that he will soon recover and once more become a productive member of the tribe. However, if food and other resources are scarce, sick or injured individuals who are not expected to recover even with such help might be abandoned, euthanized, or expelled from the community. Think of lepers in Biblical times, or elderly Eskimos being set adrift on ice floes, or elderly Polynesians being consumed through ritual cannibalism. This is because, if someone with a tropical fever or a burst appendix is inevitably going to be bedridden for a week and than die, it is a waste of resources to keep feeding them when there is no hope of them ever recovering anyways.

Worse yet, if the sick person has a communicable disease like smallpox or ebola, the longer they are kept alive by food and herbal palliative treatments, the longer the period in which they might infect others and spread the disease. And of course the people most likely to contract such an illness are the tribe's healers or medicine men, who may then die and be unable to care for other sick individuals who may then recover.

So primitive societies, especially when food or other resources were scarce, often performed a sort of ghoulish triage. Those sick individuals who had illnesses or injuries which experience had shown to be temporary, those who were expected to eventually recover if given proper care, were given food and whatever medicine the local level of medical knowledge allowed. However, those who were not expected to recover were given care focused less on recovery and more on preparing their soul for the afterlife. Catholic Last Rites are an example of such practices that have survived to the modern day.

But back to evolution. If a sick individual in such circumstances was being given the primitive equivalent of Extreme Unction to prepare him to meet Mumbo Jumbo the God of the Jungle in the next life, he knew that he was doomed. In such circumstances, the optimum strategy, from the point of view of his genes, is to shut down the immune system and die as quickly as possible, thus minimizing the drain of tribal resources and shortening the period of contagiousness of whatever sickness was killing him...and thus minimizing the risk to his friends, family, and offspring. However, if he is being given food and herbal poultices and medicinal teas which experience has shown to be effective in curing his illness, the optimum strategy is to ramp up his immune system to fight off the illness or recover from the injury as quickly as possible, so he can get back to breeding and finding food for himself, his children, and his fellow tribe members.

This, I believe, is the evolutionary origin of the placebo effect. If we think we are gonna get better, and we are in a safe situation where we are being cared for by others, our bodies will try and get well as soon as possible with a full immune response. If we think we have no hope and those around us have given up as well, our immune system gives up the fight and lets us die before we become any more of a burden to those around us who quite likely share many of our genes. Thus, either way, our genes, including whatever genes code for this connection between the brain and the immune system, have the most chance of being passed on and surviving to spread throughout the population. The placebo effect is thus, in effect, much like the instincts which will lead a mother cat to fight to the death to defend her kittens.

That article I linked above included an email link to the author, and this morning I sent him an email detailing my theory. This afternoon, I recieved a response.

He liked my idea. He hadn't heard it before, and he's a researcher in this field. Good grief, I may have created a new theory in the science of evolutionary psychology!