Dopamine, contrary to what many people believe, is not about pleasure.
It is an ancient molecule, the processing machinery of which is conserved in mammals, birds, fish, insects; This is also the case in roundworms, which have only 302 neurons in their nervous system.
Five hundred million years of evolutionary persistence suggests that dopamine serves something more fundamental.
What is that?
It inspires us. The Latin root of that word, motivus, means to drive or inspire; And dopamine, in the strict (and philosophical) sense, is about speed. This is why people who have too little of it – for example, people with Parkinson’s – become stiff and unable to move easily.
More importantly, dopamine helps us decide which direction to move. Meaning, it’s not about the pleasure as much as it is about the chase, it’s about the thrill of the chase. This was evidenced by the work of biologist Richard Palmiter in the 1990s. In their experiments, mice that were genetically engineered to produce no dopamine did not move, and starved to death even when there was food nearby.
When researchers placed the food directly in their mouths, they chewed and swallowed normally. The machinery of eating and liking was intact. What was missing was longing; The will to move towards it.
Once dopamine decides it’s worth pursuing something, it reinforces the learning it gave us and commands: more!
In their best-selling book The Molecule of More (2018), neuroscientist Daniel Lieberman and physicist-author Michael Long argue that dopamine is related to what is out of reach spatially, socially, or in the future. The moment we actually get the thing, the dopamine calms down and other neurotransmitters – what they call “here and now” molecules, like serotonin – take over the experience of getting it.
As long as the reward is out of reach, the dopamine system is at work, helping us assess the trade-offs we have to make to obtain it. Once it’s in hand, the dopamine kicks in, making the world feel a little flat. Evolutionarily, this makes sense. In a world of scarcity, you want to be on the lookout for the next shiny thing. It also clarifies a familiar paradox: “wanting” feels intense and important, while “having” feels ephemeral.
Thanks to the work of neuroscientists like Kent Berridge, we now know that cravings and liking occupy different biochemical pathways in our brain. There is a large dopamine-driven network that underlies the search, and the hedonic hotspots are a hundred times smaller that generate the actual feeling of pleasure.
Now onto the dark side of dopamine. It’s really great at helping us survive in an uncertain world, but it was not designed for a reality in which human engineering can turn the reward settings up to 11.
Substances like cocaine, alcohol, nicotine, and processed sugar push the dopamine circuits into overdrive, and the neural pathways (cues like location, time) that lead to the hit aren’t just lined up; They are in capital letters, bold and highlighted in our brain. And thus, we become addicted.
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In The Hacking of the American Mind, endocrinologist Dr. Robert Lustig argues that the systems of craving (mediated by dopamine) and satisfaction (mediated by serotonin) work in opposition.
Excess dopamine depletes serotonin, making us sad and craven, unable to enjoy life’s simple pleasures. Dopamine and serotonin also compete at the level of their amino-acid precursors. Tyrosine (for dopamine) and tryptophan (for serotonin) both travel in the same taxi – the L-type amino acid transporter or LAT1, across the blood-brain barrier – to cross into the brain. Since seats are limited, overcrowding of one in the cab means fewer rides for others.
Modern engineering hijacks dopamine on three fronts: highly palatable food, digital feeds that combine endless signals with micro-rewards, and frictionless convenience that blurs the distinction between wanting and getting.
Let’s start with food. A remarkable set of experiments by Paul Johnson and Paul Kenny showed how rewiring occurs. They implanted an electrode into the pleasure circuitry of rats and connected it to a lever that the rats could press to receive a short electrical sound. By finding the minimum current that worked for each rat, the scientists established a minimum reward threshold. When that threshold increased, it meant the rat’s reward system was becoming numb.
Next, they divided the rats into three groups. One received only lab chow, nutritious but uninteresting. The other had an hour a day of junk food: bacon, sausage, cheesecake, frosting, chocolate. The third got round the clock access (RTCA) for it.
Within 40 days, the RTCA mice became obese, and were consuming almost twice as many calories as other mice fed lab chow. The limit of their reward increased. They needed much larger shocks to feel happy than rats in other groups.
When they were forced to eat only chow (a form of drug abstinence), they ate much less and lost weight. Importantly, their reward cap remained high for the entire two weeks of withdrawals.
What makes this particularly scary is that, in another experiment, cocaine-addicted rats regained their pre-addiction reward threshold after about 48 hours of abstinence. Was junk food more addictive than cocaine?
To check how deep the rewiring went, the scientists conducted another test. Each rat was given 30 minutes of junk food daily. While they were eating a cue light pulsed and during that light there were painful shocks on the floor. The rats quickly learned: the light is on, the pain is coming.
On the day of testing, the lights flashed but there was no shock. Chow-only and one-hour rats reduced their food intake rapidly after receiving the warning (even when junk food was available), but the obese rats continued to eat. They understood that danger was coming. He ate anyway.
Their behavior was disconnected from the outcome – the defining characteristic of compulsion.
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What does this mean in human terms?
Well, in a sense, we already resemble obese RTCA rats. A Jordanian survey of 675 food-delivery-app users found that 87% said fast food was their most popular order; More than half said it was hard to find healthy options. A Chinese study found that takeaway food contained 20% more meat, 15% less grains, and had a 53% higher carbon footprint than home cooking. One respondent in a small UK study put it best: “It’s quite addictive in the way that it’s very convenient to order… I’m eating unhealthy.”
Apps are also designed to be addictive. They take advantage of a powerful psychological mechanism called a variable ratio schedule of reinforcement. If someone gets a reward every time, the novelty wears off and the dopamine decreases. But if the reward is unexpected, dopamine production skyrockets.
Think about a slot machine: you know the prize is great, but don’t know if the next try will yield it. This is what makes slot machines addictive and profitable, and it is why casinos devote more square footage to slot machines than anything else.
Phone and app makers understand this. The phone’s notification badge takes advantage of an evolutionary alarm color, red (blood, ripe fruit, fire), which attracts attention. The ping itself acts as a habit-loop signal. Is that ping an important meeting, delivering an offer or a message from a lover? The variable cue reward ensures that dopamine increases upon sound.
Apps add extra lures, essentially mimicking slot machines. Physically pulling down a feed and waiting a beat for new content mimics the action and anticipated delay of pulling down a lever on a slot machine.
Eye-watering images keep the user engaged, and gamification keeps the dopamine spikes flowing all the way: order placed (small reward, sometimes confetti thrown), handed to driver (small reward), driver on his way (small reward). The food here is delicious (big reward). Packaging, carbon and food waste are not recorded as prominent.
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Should we be worried?
Some devastating figures are emerging. Researchers at the University of Bonn and SMERU Research Institute in Indonesia tracked health metrics in 497 districts in Indonesia as super apps like Gojek and Grab launched city-by-city between 2015 and 2018, comparing places that got the apps with those that didn’t.
The study found that in districts where food delivery became available, BMI increased by 0.57 points, waist circumference increased by 3.2 cm, and overweight incidence increased by 4.6% compared to comparable districts without food delivery.
Other research shows that dopamine addiction impairs mental and emotional resilience. Apps that deliver constant dopamine hits reduce the sensitivity of the brain’s response, leaving the user in a state of repeated or chronic craving; One in which simple pleasures like a book or a walk seem flat.
When attention is snatched away by pings and sharp cuts, it becomes difficult to maintain sustained focus for intensive work. The loop also steals sleep, further reducing emotional resiliency (and further upsetting the dopamine system). One addiction can pave the way for another, as Lustig and others noted: Give up the phone and the person finds themselves sugar, alcohol, shopping, porn — anything to re-light the dim circuits.
Dopamine is not the villain. As Dr. Anna Lembke, a Stanford psychiatrist and author of Dopamine Nation (2021), says, it helps us be “prepared to survive in a world of scarcity.”
But in today’s world, the molecule that once helped us survive scarcity is being used to sell surplus goods. Somewhere in that irony lies a warning.
(Mridula Ramesh is a climate-tech investor and writer. She can be reached at tradeoffs@climateaction.net. Views expressed are personal)
