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LostInParadise's avatar

Is there an evolutionary explanation for addiction?

Asked by LostInParadise (18099 points ) July 25th, 2012

I did a Web search and all I found was speculation, mostly not very convincing. Let’s leave aside emotional addiction and just concentrate on physical addiction, and to narrow the discussion still further, let’s concentrate on the most common form of addiction, which would be alcohol addiction. It is not just humans that can become addicted. Laboratory mice can also become alcoholics.

I don’t know how often mice in the wild become alcoholics. I would guess not too often. Such an addiction would not seem to confer any advantage to either plant or animal. Maybe there is some underlying body mechanism that the alcohol triggers. Hunger and thirst are types of cravings with obvious advantages. People can also develop a craving for salt if there is a deficiency. Might it be that there is a generalized craving mechanism in the brain that is necessary for the development of drug dependencies? Just a speculation, and not even a complete explanation, but no worse than what I have come across on the Web.

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8 Answers

thorninmud's avatar

What evolution accounts for is the brain’s reward system. This is the feel-good mechanism that encourages us to do things that are beneficial to our survival, like eating, drinking and mating. This reward mechanism is based on the release of neurotransmitters, especially dopamine and serotonin, triggered by certain stimuli. We feel pleasure as a result, and so will want to repeat those activities. This confers an obvious survival benefit.

Certain substances, though, can hijack this reward mechanism in various ways. Some mimic the effects of the neurotransmitters. Others artificially increase the release of the neurotransmitters. Alcohol does the latter, but also has the pernicious effect of decreasing the sensitivity of the receptors over time, so that naturally released neurotransmitters have a diminished effect. This causes the alcoholic to feel an increased need for the release provided by the alcohol. And because of the lower sensitivity, more and more alcohol will be required to provoke a release.

So evolution simply put the mechanism in place. The chemical addiction exploits that mechanism.

josie's avatar

@thorninmud Took my answer and did it better. Evolution creates all sorts of possibilities to interact with the external environment. That is not to say that human beings cannot discover them and use them in a fashion counter to why they evolved.

Blueroses's avatar

It’s a great question. One, I wonder, if it might be more related to social evolution?

I’ve been asking myself often, lately, about the prolific prescriptions for SSRI drugs. Are we redefining “normal”? Are we passing on a dependency on seratonin reuptake inhibitors to the next generations?

Pandora's avatar

Well all animals (including humans have basic needs to fulfill). Eating, drinking, sleeping and sex. Sex and food are both very addictive. Food to survive and sex to reproduce. Both are hardwired pleasures. Although water does not seem to do the same as alcohol, alcohol does numb our pain. It could be the lack of feeling pain is also a pleasure of sorts. But alcohol does also increase sexual desire as well, so it goes back to the need to procreate.

rooeytoo's avatar

I’ve often thought about this because when alcohol is introduced into more primitive cultures, addiction seems to suddenly become a huge problem where it was not before. But to my casual observations, it seems there was always a drug of choice in all cultures regardless of how advanced or primitive. But in primitive conditions, more time and energy are needed to survive, hunting or gathering just to eat, building shelters, making body coverings, there simply was not enough leisure time in which to indulge in addictions. I can see this in just the time period from when my grandfather was alive to now. He was a farmer and for many years had no gas powered vehicles to make his life easier, he used horses and worked from sunup to sun down 7 days a week, his wife also. There was no time for an addiction to drugs or alcohol, he did however smoke a pipe and still lived to his mid 80’s. Now most have a 40 hour work week, a power mower to do the lawn. I don’t have to list them, our lives are filled with time and energy saving devices that my grandparents never dreamed of, so I and everyone else has a lot of time to now devote to addictions. Anyhow, bottom line as I see it is that there were always addictive substances and behaviours around, it is simply a question of how much time there was to waste on them. Idle hands are the devil’s workshop.

I realize this is an overly simplistic opinion but I nonetheless think is has its place in the list of reasons why!

LostInParadise's avatar

@thorninmud , Thanks, that is a more specific statement of what I was stumbling towards.

LostInParadise's avatar

I am still not sure about the physical effects of addiction. Why is it so painful to withdraw? I don’t know about alcohol, but the process of cold turkey withdrawal from opiates is reputed to be extraordinarily painful.

This morning I heard a story on the radio about Suboxone, which is used to treat patients with heroin or prescription drug addictions and, as the article explains, worked its way onto the black market. This gives an idea of how it works, but it is still unclear how it eases the process of withdrawal.

rooeytoo's avatar

Many have died going cold turkey off alcohol.

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