Steven Pinker (the evolutionary biologist) recently released ANOTHER book, entitled “The Better Angels of Our Nature.” In it he shows how violence has declined over the last 30,000 years of human affairs. And he says that’s due to the rise of competing characteristics, like cooperation, self-control, and empathy. According to Pinker and others, human characteristics like these arose from brain evolution. For example, our urge to cooperate evolved over time, because the laws of natural selection favoured a brain with plenty of social circuitry. (A lot of this circuitry is thought to be in the medial prefrontal cortex, just in front of the ACC.) When a tendency or a characteristic improves your ability to function and survive, and especially your ability to produce and raise children, then you’re more likely to have more kids (who also have more kids, who also have more kids) than your neighbours. I mean, wouldn’t you pick a cooperative, empathic, self-possessed partner over a raging savage to have your babies with? So then the biological quirk that gave you that quality — in this case a more humane brain — becomes a part of human nature. It beats out the competition.
What about addiction? We know that the tendency to pursue specific rewards (drugs, booze, porno, food, internet gambling, feet if you’re a foot fetishist, etc.) grows easily into addiction. That’s why so many of us are addicted to something. And we know that certain brain processes, like the rise in dopamine whenever you’re reminded of the thing you want, are what make addiction happen. In fact, much of the prefrontal cortex seems prewired for addiction. Increased dopamine flow cultivates more and more synapses in the orbitofrontal (lower/prefrontal) cortex, and in the nearby ventral striatum. These synaptic networks come to represent the details, angles, images, and the beatific value of the thing you crave. Which dredges up more dopamine from the brain stem, so you wire up more synapses in the addictive network, and on and on it cycles. No wonder we’re easily addicted. Our brains seem perfectly designed for it.
Addiction as a byproduct of brain evolution
Yet, brains did not evolve to make us better addicts! That wouldn’t make sense. Addicts are not very functional (except when it comes to meeting certain needs), they often don’t survive as well as most, and they make relatively lousy mates and parents. The brain processes that underlie addiction should have been weeded out, not strengthened, by natural selection.
Except that natural selection (evolution) doesn’t explain everything about being human. (As argued most forcefully by Stephen Jay Gould, one of Pinker’s detractors.) A lot of human characteristics are byproducts, accidents, that arise from structures designed for different purposes. For example, half the people I know over the age of 35 have back problems. Did back problems evolve because they’re adaptive? Of course not. Back problems are a result of walking around with an upright spine, something our ape ancestors didn’t have to worry about. Having an upright spine is good for a lot of things. Like having your hands free to do stuff while your feet take care of locomotion. In the same way, I think that addiction is a byproduct (a nasty one, quite often) of having a brain designed to maximize goal-pursuit in an uncertain world.
A circuit evolved for goal-pursuit
The circuitry connecting the orbitofrontal cortex and ventral striatum is a beautifully crafted machine for learning what you like and pursuing it with single-minded purpose. Its fuel is dopamine, sucked up from the midbrain (upper brain stem). And this machine sends messages directly to the premotor and motor cortex, which trigger behaviour, action, in pursuit of the good things in life. This machine evolved so nicely because it’s really really important to pursue valuable goals. Immediate goals. And not all those goals can be prewired from birth. You need to learn them as you go along. So the goal-pursuit circuit is flexible. It learns. It’s always open to try new rewards, and then to pursue them if they’re as good as they look (or taste, or smell). That’s why we pursue goals ranging from fruit, to fries, to Ferraris. We go after money — a relatively recent invention — because it’s really nice to have. It makes life better. We go after romantic partners deemed to be attractive by movie and magazine images. We can learn to go after anything, full bore, if it attracts us. And that’s how we get ahead in life.
But it’s also how we get addicted. The goal-pursuit circuit is a bit too flexible. Cocaine high. Oh yeah. That feels good. Want more. Got to get it. That drink at the end of the day. Feels good. Want it. Stop at the liquor store on the way home. These tendencies eventually cause us a lot of suffering, but they are simply byproducts of a brain that evolved to seek rewards, based on their attractiveness, and to pursue them with almost relentless energy.
When your back-ache gets bad enough, you start doing physio or yoga, so that you can use your upright spine to its best advantage. When your addiction gets bad enough, you’d best figure out how to use the goal-pursuit circuit for what it’s designed for: to be successful and happy, to avoid suffering, and — of course — to feed the little ones back at the cave.
This post also appears, with a bit less detail, on my “other” blog on the Psychology Today website. I know, I have to consolidate…
Informed by unparalleled neuroscientific insight and written with his usual flare, Marc Lewis’s The Biology of Desire effectively refutes the medical view of addiction as a brain disease. A bracing and informative corrective to the muddle that now characterizes public and professional discourse on this topic.” —Gabor Maté, M.D., author of In The Realm of Hungry Ghosts: Close Encounters With Addiction
Marc, one of your most interesting posts yet!
Dave
Thank you, sir! I’m quite pleased with it myself (modesty, always modesty)
Is the part of the brain under sized at birth that receives the “Rewards” or is a lack of nurturing as a child that cause some addictive dependency? Is the use of a stimulant or mood brightener, not a avenue for self medicating an underline condition. Why can’t I get an alternative legal alternative medication for cocaine like methadone or suboxone for opiate users?
I guess what you mean is coffee.
But in fact most of the brain is not undersized in infancy. There are actually way more synapses in infancy than later on, and they get pruned with experience. Of course you grow a few new ones on the way, but the point is to ditch that “blooming buzzing confusion” in exchange for a super-efficient goal-seeking machine.
🙂
“super-efficient goal-seeking machine”
Okay, let’s get that up in lights!
I don’t quite get what you mean by giving up the “blooming buzzy confusion”? I was always under the impression that as we grew up our brains where wiring up, sort of speak, threw childhood till around age 10. If this is true and a person dose not get the nurturing need during that stage of development, Is that part of the brains reward defiant in some way? and if so would not that person seek out Rewards of fulfillment in that area to compensate their need. In saying so, that person in having found that Reward through drugs or alcohol not entitled to a prescription medication to address that need. eg: mood brightener / simulant?
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Hi Marc,
A friend sent me this in response to an article in the Globe and Mail (Nov. 4/11) by Gerald Caplan regarding Professor Pinker’s book positing the decline of violence.
If Caplan accepts that violence is on the decline, I’d be interested to learn when he believes that it peaked !!!! Just the numbers belie this nonsense. Forget wars, there are now 3 plus billion women on this planet and over 70% of them are subjected to abuse and violence. Caplan should perhaps subscribe to:
http://ipsnews.net/genderwire/
Hi Linda, I’m not sure where you get your stats, but I think Pinker’s argument is convincing and refreshing in this pessimistic age. Whenever people say that everything’s getting worse, I think about the absence of slavery in 99% of human societies (a few hundred years ago, nearly everyone either had a slave or was one), I think about a black president in the US, a mere 50 years after legal racial segregation in half the states, I think about the world literacy rate that is nearly 100% now — used to be closer to 1% even a few hundred years ago. And, oh yeah, violence.
Well, it’s true that there were a few unpleasant blips in the 20th century (World Wars I and II, the Holocaust)…and it was perfectly acceptable to beat up gays and people of colour. But wars have been a lot smaller since 1945, and gays have finally won acceptance in many parts of the world. If you look at the general trends, we’re just getting better and better. Wars these days are localized. Wars in the old days had names like the Hundred Years’ War, the Crusades, etc). And murder was 5 times more common a mere two centuries ago, in England at least (from Pinker’s book).
I don’t know the stats on violence against women, but I do know that most people and most cultures condemn it, there are many organizations dedicated to fighting it, and women are leaders of several of the richest and most powerful countries in the world. Think of all that, relative to say The Suffragette movement: women were universally mocked for espousing the very idea that they should have a vote.
Things are far from perfect, but we’re heading in the right direction. (except for the little matter of global warming, which even the Republicans are starting to acknowledge). We’ve still got lots of work to do.
This is one of the most fascinating theories I’ve heard on addiction. Even better, it makes complete sense to me. The question that always comes to my mind, though, is why are some people much more wired for addiction than others? Does it just come down to basic human physiological differences — such as, for example, that one person gets a sublime high from listening to Beethoven and the other to Celine Dion or Metallica?
Maybe the musical one was a bad example. What I meant was physiological differences in the brain. Do some people’s synapses just fire faster or differently than other people’s in response to certain stimuli — which are different for each individual? In that sense, is it a genetic thing? And then if environmental factors (esp. growing up) are factored in, some people are just more susceptible to addiction? Are addictive brains more developed for reward?
Another question I have is about the term “addicted brain.” I’ve often heard about the addict personality — if you’re addicted to one thing, you’re susceptible to being addicted to another. Well, I was a raging, binging alcoholic, but I’ve smoked one cigarette a day for ten years and I’ve never wanted more than that. And I have no other addictions. This puzzles me.