Scientists have found that the seven deadly sins aren't all bad. Consider this your official permission to give in to temptation.
Quit beating yourself up about your unused gym membership: It’s only 10 percent your fault! Turns out, laziness is largely genetic. In 2004, Timothy Lightfoot, currently a kinesiologist at Texas A&M University, began publishing studies about what separates athletes from couch potatoes. He bred two types of mice—energetic and lazy—and then measured how far they ran on the exercise wheel. Active mice clocked five to eight miles per day—the equivalent of a human running two marathons in a row. By contrast, the sedentary mice ambled about 0.3 miles per day, with the laziest of the bunch stuffing wood shavings around the wheel to turn it into a bed. When Lightfoot examined the rodents’ DNA, he found that heredity accounted for about 50 percent of the differences in their activity levels. Since then, studies on humans suggest that up to 90 percent of our energy levels are controlled by genetics.
But there’s a reason laziness hasn’t been weeded out of the gene pool. Back when our cave-dwelling ancestors weren’t scrounging for food or running from saber-toothed tigers, they lounged to conserve calories. Even in civilized society, where inventions from banana peelers to Segways encourage sloth, laziness can give us an edge. One 2011 study by University College London found that employees who work more than 11 hours a day have a 67 percent higher risk of heart disease than slackers. Other studies have linked long work hours to higher levels of stress, fatigue, depression, musculoskeletal disorders, chronic infections, diabetes, and death. Yikes! Sounds like you’re safer staying on the couch.
Of all the cardinal sins, lust has perhaps the most obvious good points (procreation!) and as long as you avoid its potentially nasty side effects (chlamydia!) it can be measurably good for your health.
In a Duke University study that followed 252 North Carolina residents over 25 years, medical sociology professor Erdman Palmore found that men who had sex more than once a week lived two years longer on average than men who had it less often. For women, quality trumped quantity: Those who said they enjoyed sex lived seven to eight years longer than women who weren’t so into it. Sex keeps people alive and kicking, Palmore says, because it comes with both physical and psychological benefits. “It gets your heart pumping, plus it makes you feel good about life,” he says.
If a longer life span isn’t convincing enough, here’s another perk: improved public speaking skills. In a 2006 study, Stuart Brody at the University of Paisley in Scotland forced volunteers to give a speech to a panel of bored judges. After the orators slinked offstage, Brody took their blood pressure, which was sky-high for most—except for the people who, in diaries of their activities, said they’d had intercourse at some point in the past two weeks. Sex, it seems, doesn’t just keep us calm; it’s a pretty good antidote for stage fright.
At the National Institute of Radiological Sciences in Japan, scientists slid 19 volunteers into an MRI machine, then summoned the green-eyed monster by presenting them with a description of someone who had it all—great job, great relationship, great life. As participants read about the high achiever, an area of their brains called the anterior cingulate cortex (ACC) ignited. This spot also flares in the presence of physical pain, proving that envy really does hurt. However, ACC activation was only induced when the subject and object were similar in sex, age, class, or background. “[If] the possession of the target person is superior and the comparison domain is self-relevant, we feel intense envy,” reported Hidehiko Takahashi in a 2009 study.
But feeling intense jealously actually spurs the envious to improve their performance. “Individuals experiencing envy in response to another’s advantage are being appropriately alerted to the advantage and motivated to commence corrective action,” note psychologists Sarah Hill and David Buss in the book Envy: Theory and Research. “Over the course of evolutionary time, individuals who did not feel subjective discomfort in these situations would likely have been out-competed by their more envious counterparts.”
Some scientists have even proposed that envy may help explain why humans are less prone to hierarchy than many species and are constantly rebelling against kings and dictators. Nader Habibi, an economics professor at Brandeis University, argues that Tunisia’s successful 2011 rebellion against president Zine El-Abidine Ben Ali sparked a wave of “democracy envy” throughout the Middle East, leading to riots that toppled other despots, starting with Egyptian president Hosni Mubarak. “What happened in Tunisia filled Egyptians with envy,” Habibi says. “For the average Egyptian, the emotional cost of living under Mubarak’s authoritarian rule suddenly rose skyhigh. ‘Are we less courageous than the Tunisians?’ they asked one another. As this question echoed in their ears, envy turned to outrage, compelling them into the streets. The rest, of course, is history.”
Between Bernie Madoff and, well, everyone involved in the financial crisis of 2008, greed has gotten a bad rap. One of the most confounding questions: Why do wealthy bankers and CEOs still want more? In 2000, financial reporter Jason Zweig set out to answer this question by having his brain scanned via MRI when he played gambling games. During one experiment, scans revealed that his brain lit up like a slot machine while he anticipated winning five bucks. Once he’d earned the money, however, his neural circuits cooled off. “Making money feels good, all right; it just doesn’t feel as good as expecting to make money,” Zweig explains. “In a cruel irony that has enormous implications for financial behavior, your investing brain comes equipped with a biological mechanism that is more aroused when you anticipate a profit than when you actually get one.”
In an evolutionary sense, of course, greed is essential to survival. When resources are scarce, people who hog more than their fair share will last longer than those who don’t. And it goes beyond individuals. Economists in Switzerland have found that a moderate level of greed is beneficial for society as a whole. In 2010, Dirk Helbing, a professor of sociology, modeling, and simulation at ETH Zurich, announced that he’d designed a computer model to test the effects of greed on social cohesion. Not surprisingly, a high greed society led to a “freeloader effect” where everyone was out for themselves and anarchy reigned. But the low greed society, long thought of as the utopian ideal, was also bad for social cohesion: Individuals had such a low threshold for contentment that they didn’t bother pitching in to the common good. In the moderate greed model, Helbing writes, “cooperation and agglomeration emerged, reaching a stationary state where clearly more than one half of the population is cooperative and individuals tend to agglomerate and form cooperative clusters.” In other words, a little greed is good for society.
Need a good excuse to cram handfuls of pork rinds into your maw? Science has your back. While there are plenty of downsides to weight gain (studies show heavier people don’t get hired or promoted as much), an expanding waistline can tip certain scales in your favor.
In 2005, Leif Nelson, a professor at New York University, published a paper detailing how he’d parked himself in front of the college cafeteria and asked entering and exiting students to write down their ideal weight preference in a mate. Surprisingly, men changed their answers based on two factors. Those who hadn’t eaten yet wrote that they preferred their girlfriends to weigh an average of 125.5 pounds—2.7 pounds heavier than men who’d already had their fill of cafeteria fare. And those with less money in their wallets preferred women to weigh 127.2 pounds—2.3 pounds heavier than men who had plenty of cash. Nelson’s theory is that our less prosperous evolutionary pasts are to blame. Back in our cavedwelling days, a few extra pounds on a woman didn’t spell the difference between a size six and an eight; they determined whether she could stave off starvation a little longer, giving a man ample time to bring home the mammoth bacon. On the other hand, Nelson found that women’s tastes in a man’s weight remained constant regardless of whether they’d eaten or how much money they had.
For men, a few extra pounds come with even more surprising benefits. In a 2010 study by the University of Missouri, volunteers were shown pictures of politicians, some of which had been doctored to make the politicos appear obese. When asked to rate how well these candidates would perform on the job, the portly men were deemed more trustworthy than the thin ones.
As anyone who's driven in rush hour traffic can attest, wrath is a sin that’s hard to avoid. And while society tends to see angry people as irrational, those with tempers might be seeing things more clearly than their even-keeled friends. In 2007, UC Santa Barbara scientist Wesley Moons had volunteers write about their hopes and dreams, then trashed some of the essays right in front of the writers to push their buttons. After that, Moons presented written proposals on a variety of topics, like whether high schoolers should have to take comprehensive exams in order to graduate. In these proposals, some of the arguments were strong (“comprehensive exams improve students’ job prospects”) while others were noticeably weaker (“someone’s cousin took that exam so others should too”).
When Moons asked his study subjects to pick which case was most compelling, the irate volunteers didn’t waver: They chose the stronger argument. Meanwhile, the mellower control group seemed equally lulled by both strong and weak arguments. Anger, Moons concluded, appears to sharpen our analytical skills—most likely because it forces us to ignore irrelevant details. “Anger increases our attention and focus, which helps us process information more thoroughly,” says Moons. “We’ve moved from a time when anger is this terrible thing to a more nuanced view that it can be beneficial.”
Pride is traditionally considered the root of all sins—it’s what caused Satan to think he could do a better job than God, which got him kicked out of heaven. But as it turns out, our bodies are programmed for pride. In 2005, Julian Keenan of Montclair State University in New Jersey pinpointed the area of the brain responsible: the medial prefrontal cortex. In his experiments, Keenan managed to “turn off ” pride by asking volunteers to don a cap of electromagnetic coils that disrupted the firing of neurons via a process called transcranial magnetic stimulation, or TMS. Keene then gave them an “IQ test” where he ran a bunch of obscure words by his study subjects, asking if they knew what these words meant. What he didn’t mention was that it was a trick quiz: Half the words were made up. “An IQ test does not measure pride. However, pretending to know items on an IQ test that aren’t real is a measure of pride,” Keenan says. Sure enough, pride prompted the cap-less control group to “know” many of the fabricated words, while those subject to TMS admitted ignorance.
Pride is clearly natural, but it also may be necessary. Keenan has found that people with no pride tend to be clinically depressed. Originally, “I thought people with depression saw themselves as unrealistically bad,” he says. “It turns out that people without depression see themselves as unrealistically good.” Another upside of pride is that it fuels further accomplishments. In a 2008 study, Lisa Williams and David DeSteno of Northeastern University gave subjects a task and told some of them that they’d aced it even if they hadn’t. They then grouped the participants into teams to solve puzzles. Participants who’d been primed to feel pride tended to take charge and handle the puzzle pieces more than those who hadn’t gotten feedback on the earlier task. The results convinced Keenan that pride is an essential evil: “Pride allows us to go out and take risks and do stupid things, and some of those stupid things pay off pretty well.”
This article originally appeared in mental_floss magazine, available wherever brilliant/lots of magazines are sold. Get a free issue here!