Over the past decade, two facts have become increasingly obvious – that our ever-increasing consumption is wrecking the planet, and that continually chasing more stuff, more food and more entertainment no longer makes us any happier. Instead, levels of stress, obesity and dissatisfaction are spiralling.

So why is our culture still chasing, consuming, striving ever harder, even though we know in our sophisticated minds that it’s an unrewarding route to eco-geddon? New scientific studies are helping to reveal why. It’s our primitive brains. These marvellous machines got us down from the trees and around the world, through ice ages, famines, plagues and disasters, into our unprecedented era of abundance. But they never had to evolve an instinct that said, “enough”.

Instead, our wiring constantly, subliminally urges us: “Want. More. Now.” Western civilisation wisely reined in this urge for thousands of years with an array of cultural conventions, from Aristotle’s Golden Mean (neither too much, nor too little) to the Edwardian table-saying: “I have reached an elegant sufficiency and anything additional would be superfluous.”

Consumer culture ditched all that, though, constructing instead an ever more sophisticated system for pinging our primitive desire circuits into overdrive. It got us to the point where we created everything we need as a basis for contentment. Now it’s rushing us past the tipping point, beyond which getting more makes life worse rather than better. And it’s making our brains respond more weirdly than ever.

Our old wiring may condemn us to keep striving ever harder until finally we precipitate our dissatisfied demise. But, instead, we could learn to practise the comfortable art of “enough” in this overstuffed world. There is a broad armoury of strategies we can adopt to proof our brains against the pressure to pursue and consume too much, to work too hard and to feel constantly inadequate and underprivileged. The most fundamental of these is knowledge: forewarned is forearmed. So here are just a few of the myriad unexpected ways in which our culture pushes our wanting brains into overdrive.

Stuffed by celebs

Consumer society has invented a barrage of ways to stimulate our want-more brains’ acquisitive instincts, but the latest and greatest of these innovations is celebrities.

The desire-driven wiring of our primitive brains evolved in the Pleistocene era, between 130,000 and 200,000 years ago. It was moulded by half-starved hunter-gatherers and farmers whose crops frequently failed. Those who kept going survived to give us their yearning genes. That wanting instinct gets fixated on material goods. We evolved to desire possessions as no other creature does. Neolithic cave sites may partly explain why. Many contain millions of hand-axes – far more than cave-dwellers ever needed. Anthropologists believe that the best axes were not just prized tools, but precursors of Ferraris and Jimmy Choos. Owning Stone Age bling displayed your high reproductive value.

Nowadays this status-chasing urge makes designer goods sorely alluring, even if they make no real difference to our luxury-glutted lives. Our hunter-gatherer brains seem wired to experience constant buyers’ urges, too. Brain scans by Emory University in Atlanta show how the reward-chemical dopamine is released when we spot a product and ponder its purchase. But only the anticipation, the hunt, releases dopamine. After the deal is sealed, the high may evaporate in minutes, leaving what shop-owners call “buyer’s remorse”.

One of the most successful ways to dispel that remorse and stimulate more buying is celebrity endorsement. Manufacturers spend millions paying the likes of Elizabeth Hurley to squirt their fragrance and Daniel Craig to handle their gadgets. Neurologists at Erasmus University in Rotterdam report that our ability to weigh desirability and value is knocked awry if an item is endorsed by a well-known face. This lights up the brain’s dorsal claudate nucleus, which is involved in trust and learning. Areas linked to longer-term memory storage also fire up.

Our minds overidentify with celebrities because we evolved in small tribes. If you knew someone, then they knew you. If you didn’t attack each other, you were probably pals.

Our minds still work this way, giving us the idea that the celebs we keep seeing are our acquaintances. And we sorely want to be like them. Humans are born imitators: this talent enabled us to develop far quicker than our competitors could via biological evolution alone. One chimp can watch another poking a stick into an anthill and mimic the basic idea, but only humans can replicate a technique exactly. We must choose carefully whom we copy and have evolved to emulate the most successful people we see. Thus, many of us feel compelled to keep up materially with celebs, the mythical alphas in our global village.

We’ve also evolved to despise being out of the in-crowd. Brain scans show that social rejection activates brain areas that generate physical pain, probably because in prehistory tribal exclusion was tantamount to a death sentence. And scans by the National Institute of Mental Health show that when we feel socially inferior, two brain regions become more active: the insula and the ventral striatum. The insula is involved with the gut-sinking sensation you get when you feel that small. The ventral striatum is linked to motivation and reward. To stave off the pain of feeling second-rate, we feel compelled to barricade ourselves behind evermore social acquisitions. That kept our ancestors competitively stretching for the next rung of social evolution, but now it has locked us into a Pyrrhic battle because the neighbours can also just about afford the latest status symbols, too.

Infomania

Our brains have an instinctive way of handling information that worked well until very recently: if we are confused or worried by what we learn, we feel driven to learn more. Now, however, technology has brought an info-blizzard. We see, for example, more then 3,500 sales messages a day. More than six trillion business e-mails were sent last year. It’s bewildering, so we feel driven to seek even more information in quest for the one golden fact that explains it all.

The roots of this lie deep. On the savannah where our ancestors evolved, you needed to make the best of all the information you had. Novelty – new faces, shapes and concepts – was rare and would spark a mental conflict between fear and curiosity. It would take strong inquisitiveness to stimulate an early human to explore matters such as: “What happens if I kick that lizard?” The people who explored often won the best chances to feed and breed. Over time, a reward system evolved in primitive brains to encourage information gathering.

It is still busily at work. A University of Southern California study reports that when we grasp a new concept, the “click” of comprehension triggers a shot of heroin-like opioids to reward the brain. The researcher Irving Biederman says human brains have a cluster of opioid receptors in a brain region associated with acquiring new information: we evolved to get high whenever we learn something. “We are designed to be info-vores,” he says. “When you are trying to understand a difficult theorem, it’s not fun. But once you get it, you feel fabulous.”

The reward system is overridden by more pressing needs for food or safety, but on today’s comfy sofas we have no predators or famines, so infomania can run amok, creating a mass desire for scary news, banal texts and celeb gossip. We keep seeking new sources for our mini-kicks because the opioid reward diminishes each time a novel experience is repeated.

Biederman’s scans of volunteers’ brains show they get less stimulation each time they see the same picture. In reply, the media industry offers increasingly quickfire stimuli that squeeze our “duh, seen that” response ever harder, intensifying our novelty addiction and curtailing our attention spans. This causes confusion: a survey by the Henley Centre, the social forecasting company, says that we are a society of info-hoarders, the new-media equivalents of crazy types living in homes crammed with newspapers. More than 70 per cent of people ticked the survey box saying: “I can never have too much information.” But more than half also said that they don’t have time to use the information they already have. One way of trying to cope with this overload is to cram in more information-seeking. Most twentysomethings now watch TV while also being online.

On top of this, our 24-hour rolling-news culture keeps us constantly story-chasing. Our minds fill with exaggerated anxiety as they witness regular reruns of the day’s most shocking images. How many times does one have to see the same bomb-blast to get the idea? The horror is replayed continually, but we learn nothing more. Instead we become convinced that life is dangerous and beyond control. So we feel compelled to watch more news.

This is exacerbated by our primitive brains’ limited sense of geography: if we see footage of a far-off massacre, our minds think it must have happened close by, within range of a Neolithic human’s wanderings. We feel compelled to learn everything about this “nearby” threat. This causes a stressy cycle of continual info-seeking. Some psychology studies suggest that we should limit our news-watching to 30 minutes a day – or risk anxiety-related depression.

Appetite for destruction

Having an overacquisitive, harried, multi-tasking mindset is one of the worst ways in which to approach one of the greatest challenges that unprecedented abundance presents us: food. A quarter of Western adults are obese and a third are overweight. The majority will, it is predicted, be overweight in the next 20 years.

Our appetite will always tell us that food is fearfully scarce. Historically, it has been right. As recently as 1321, one English person in five is thought to have died of famine. First World War British soldiers were on average only 5ft 5in tall. They had grown up seriously malnourished. With food, as with possessions and information, our brains have never before had the need for an “enough” button. Tests by Martin Yeomans, an appetite psychologist at Sussex University, show that we don’t really know when to stop eating. He gave volunteers plates of pasta, but kept switching and replenishing their plates, so that they lost track of how much they were consuming. “One man happily polished off 2kg of pasta at one sitting and thought he’d had a normal portion,” he says.

Our appetite levels are intensified by constant ads and marketing. Our brains fill with reward chemicals at the mere sight of it all. The pleasure response is stronger than the one we get from eating food itself, claims Dr Nora Volkow, the director of the US National Institute of Drug Abuse. This is why food marketing is so dangerous, she says: “It stimulates an old mechanism by which nature ensures that we actually consume food when food is available. We never knew when food was going to be available next.”

This instinct is worsened by haste. Twenty years ago we spent on average 33 minutes over our evening meals. Now it’s 14½ minutes. Meals get bolted as we refuel mindlessly over desks, in front of the telly, reading or on the phone. A 2006 survey found that fewer than 20 per cent of us regularly give our plates our full attention.

But being preoccupied or stressed while eating makes us overconsume, reports the journal Appetite. Your mind fails to experience the full spectrum of pleasure that it can obtain from consuming food. The “I’ve eaten loads, thanks” message fails to get sent from brain to body, and snacky pangs soon return. Kathleen Melanson, a nutrition professor at Rhode Island University, found this when she asked 30 women students to make two visits to her lab. Each time they were given a large plate of food and told to eat as much as they wanted.

When they were told to eat quickly, they consumed 646 calories in nine minutes, but when they were encouraged to pause between bites and chew each mouthful 15 to 20 times, they ate only 579 calories in 29 minutes. They also said they enjoyed their food more, felt fuller at the end of the meal and still felt fuller an hour afterwards. “Satiety signals clearly need time to develop,” Melanson says. Other research indicates that it takes 20 minutes for your brain to realise that your stomach is full, so taking time to chew undistractedly enables your mind to keep up with your golloping.

© John Naish 2008. Extracted from Enough: Breaking Free From the World of More (Hodder & Stoughton, £16.99), to be published January 24. It is available from Times BooksFirst for £15.29, p&p free: 0870 1608080 or visit timesonline.co.uk/booksfirst

PROOFING YOUR BRAIN

Change your mindset to “postmore” by challenging our culture’s ingrained assumption that “more” of everything is automatically better. We’re beset by slogans such as “Smart girls get More” and Virgin’s “Get more” ad campaign.

Grow your gratitude. Our poor, starved, frozen ancestors would cry tears of joy if they suddenly landed in our culture of abundance. Fostering our appreciation of this bounty can also block the consumerist “cool” pressure to deride so many of our fine, workable possessions as “so last year”.

Be enough We’re constantly told that we aren’t rich enough, glam enough, cool enough, networked enough, etc. This has a powerful insidious effect on our primitive, socially competitive brain circuits. It’s like a toxic substance that turns rational brains into needy toddler-like grizzlers.

NEXT WEEK Enough happiness. Why the modern imperative to be ever happier is a con

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