Humans

By Paul Raeburn and Kevin Zollman
Morgan Schweitzer
As the holidays near, we eagerly anticipate spending time with our nearest and dearest. When we gather in the warmth of the hearth, we’re so happy to see them – that is, until we end up at each other’s throats.
How do we encourage our families to behave themselves in a way that reflects how, deep down, they truly love each other? Turn to game theory, the science of strategic thinking.
Game theory underpins everything from negotiations over the broadcasting rights of big sports fixtures to schemes for improving organ donation. The mathematics of the prisoner’s dilemma – one of the field’s most famous problems – have even been applied to the hunt for new life forms in space.Advertisement
You already know more about it than you realise: whenever you find yourself considering what you should do in terms of how someone else might respond, that’s game theory. But brushing up your know-how could help you preserve family harmony over the holidays. After all, if game theory was able to help avert nuclear apocalypse during the cold war, there’s an outside chance it could get your lazy uncle to help for once.
Who will host?
The solution to this problem may appear simple. In the lead-up to the holidays, have everyone vote: Grandma’s house or Aunt Laurel’s. (You’ll have to draw straws for who gives Grandma the bad news.)
But what if there are three choices? Game theorists say you should use a Borda count. Each person ranks their preferences: 1, 2, 3. Then you add up the numbers. The host with the lowest score wins. Variants of the Borda count are used in some national elections – and even important international matters such as selecting the winner of the Eurovision Song Contest.
Who conducts the Borda count is another question. Maybe break out the straws again?
Who brings what?
That greasy green bean casserole gets thunked down on the table every year – your cousin’s contribution to the festive feast. Many people have delicious alternatives they would love to provide, but no one wants to hurt her feelings, so those woeful wilted beans keep coming back. How can you break free from this pattern without being insulting?
People expect others to behave consistently when they encounter the same situation. But whether a situation is considered the same or different can depend on how it is presented. In game theory, this is known as framing, and it can cause people to radically alter their behaviour. When told something is a business interaction, for instance, people behave more selfishly; if told the exact same interaction is social, they are more altruistic.
So switch frames. Seize on a change of time or venue. “Since we’re at Dad’s house this year, let’s change dishes.”
The last bit of dessert
If your family members aren’t arguing about politics, they’re probably squabbling over who gets the last roast potatoes or the final sliver of Stilton. How can you keep the bickering to a minimum? Game theorists recommend using I Cut, You Pick. If there are two people hankering after the last of the yule log, one slices and the other chooses.
Or, if you’re facing your first holiday after a marital separation, you might use the same technique to peaceably allocate the living room furniture, the still unused china and the fondue set. When the person doing the dividing is motivated to make the portions equally good, it’s more likely that both parties will end up satisfied. And that applies whether it’s cake or crystal.
Too much food?
It’s always the same: every year you’re begging people to take home leftovers. Everyone brings way too much food. Why? Look at their incentives. There’s no real penalty for bringing an excessive amount, but somebody might be offended if they bring too little. So change the incentives.
It works. In 2002, Ireland brought in a 15 cent tax on plastic grocery bags. Within weeks, plastic bag use dropped by 94 per cent. In England, it is down about 80 per cent since a plastic bag fee was introduced in October 2015.
How can you harness the power of incentives to reduce the extra food? Give a prize to the cook whose dish is totally gone, or make the guest with the most leftovers host next time. Now it’s not a measure of one’s love, it’s a game.
Morgan Schweitzer
Stop playing tag in the living room!
The kids are misbehaving after dinner. Mum yells, “If you don’t stop, we’re leaving!” They ignore her, and minutes later the antique lamp is in pieces. Why didn’t the children listen? They knew an overstuffed Mum didn’t really want to leave. Her warning was a non-credible threat.
The principle is the same when far more is at stake. One argument for holding nuclear weapons is to deter other countries from using theirs. But what if the other country strikes first? You can’t retaliate if you’ve been wiped out. To maintain a credible threat, the UK has “letters of last resort” aboard its four nuclear submarines: instructions for what to do in that situation. Since enemies don’t know where the subs are, or what the instructions say, the danger of retaliation is real.
For Mum though, it might be enough to threaten to make the kids do the dishes. If they know she is more than happy to follow through, it’s more likely to have an impact.
Uncle Larry never helps
Everyone else is busy straightening up the house, but Uncle Larry is on the couch playing Candy Crush. How can you make him do his fair share? It’s no use telling him that everyone thinks he should help. People pay more attention to empirical expectations, what others do, than normative expectations, what others say they should do.
In an experiment where people had a sum of money they could share with others, telling them that “most people donate” encouraged more giving than telling them “other people think you ought to donate”.
You can put empirical expectations to work with Larry. Make a point of having someone clean up around him, so he can see them doing it. He might just feel obliged to pitch in.
Game time
You are about to put your feet up when you sense an argument brewing over whether to play charades or put on Elf for the umpteenth time. What to do? Use an auction. Those in the opposing camps can bargain by offering to do chores. Whoever makes the best offer – finish washing the dishes and tidy up the kitchen – gets to pick.
“It’s no use telling someone to help – people pay attention to what others do, not what they say”
Game theorists recommend auctions for everything from hawking old junk from the attic to selling off bands of radio frequency to broadcasters. They are the best way to figure out who really cares more.
Getting the kids to share
One final trick if all else fails: the ultimatum game. Two kids get a small box of chocolates to share. How do they divvy them up? Ask Sally to keep some for herself and offer the rest to Richard. But add a consequence. If Richard thinks she’s being unfair, you will step in, divide the chocolates and take a few for yourself. That’s a credible threat, because they know you like chocolate.
A similar scenario applies in trade union negotiations or international trade deals. If the terms aren’t fair enough for everyone, they all lose out on the benefits of striking a deal.
Experiments show that people will reject a financial offer, despite losing money in the process, if they think they are getting a raw deal. Even when it comes at our own expense, we all take pleasure in punishing someone who is acting unfairly.
This article appeared in print under the headline “How to win at Christmas”

More on these topics: More

By Kate Douglas

You can read this premium archive article for free as part of New Scientist’s 2022 advent calendar. To enjoy this and other festive gems, sign-up to become a registered reader for free.
WHATEVER you’re celebrating, the holidays are a good excuse to eat, drink and make merry. Flatulence is one of the most immediate consequences of overindulging and a perennial topic of mirth. But it also raises genuine questions that you’re probably too embarrassed to ask. We’re here to help.
Are some foods fartier than others?
Beans are not the only musical foods: flatus happens when we eat any complex carbohydrates. They are abundant in beans and pulses, but are also found in fruit and vegetables, dairy products, meat, alcoholic beverages and other goodies (yes, that’s practically everything – the list of foods that can reduce your toots is short and filled with caveats).Advertisement
“Joseph Pojul made a career entertaining theatregoers with his fartistry”
These compounds cannot be broken down in the small intestine, where most foods are digested, so pass unadulterated into the colon. Here, they are set upon by some 2 kilograms of bacteria, including the deceptively cuddly sounding Firmicutes and Bacteroidetes, which ferment the recalcitrant foodstuffs. The inevitable by-product is gas.
Gut microbes are particularly perky when you indulge in festive meals, largely due to the glut of carbohydrates. However, turkey with all the trimmings packs a double punch. Brussels sprouts, onions, dried fruit, red wine and the bird all contain sulphates, which are the key component of the most noxious intestinal gases.
How much wind is normal?
This is a tough one because you have to rely on honest answers. Studies asking volunteers to monitor their own emissions suggest 10 to 20 toots a day is normal. However, Terry Bolin at the University of New South Wales, Australia, found that men let rip an average of 12 times a day to women’s seven – which may result from a female tendency to suppress emissions.
In keeping with such wide variations, other research indicates that healthy people pass between 0.4 and 2.5 litres of gas daily. Not all of this is food-induced, though. About half the total volume derives from swallowed gases. Still, what you eat makes a huge difference, so much so that regular punters given a “flatulogenic diet” have been found to produce two-and-a-half times as much gas “per anus” as they do on their normal diet.
What’s in a fart?
Even the untrained nose can ascertain that the composition of flatus is highly variable. The percentage of swallowed gas can be far higher for people with ill-fitting dentures or an addiction to fizzy drinks. These gases are mainly nitrogen and oxygen. The remainder, produced by gut bacteria, is mostly hydrogen, along with carbon dioxide and methane.
So what makes the stink?
As in any perfume, the aroma comes from tiny quantities of pungent molecules. Flatulence guru Michael Levitt at the University of Minnesota, Minneapolis, has traced its noxiousness to three sulphurous gases, which together account for less than 1 part in 10,000 of an expulsion of wind. With help from two stalwart “odour judges”, he discovered that a fart’s potency derives from hydrogen sulphide, the “rotten-egg” gas. The overall bouquet, however, depends on how this intermingles with two other main culprits: methanethiol, which smells of “decomposing vegetables”, and the “sweet” odour of dimethyl sulphide.
Are silent ones deadlier?
Although sometimes described as a “bottom burp”, a fart is more like a whistle. The greater the volume and pressure of air passing through your rear, the louder the noise. This “instrument” has been played to considerable effect by professional trumpers, most notably the Frenchman “Le Pétomane”, aka Joseph Pojul, who from 1887 made a career entertaining theatregoers with his fartistry. Pojul had taught himself to suck up air through his anus and expel it under pressure to create farts that were thunderous but fairly innocuous.
By contrast, low volume and pressure give rise to a more discreet trump. But is it more noxious? Perhaps. Levitt found that women’s flatus contained significantly more pungent hydrogen sulphide than men’s, and his judges rated it as smellier.
Women also tend to produce less flatus than men, perhaps because of suppression – suggesting they are also more likely to control the pressure of their emissions to avoid drawing attention. This logic hints that a fart’s bark may indeed be inversely correlated with its bite.
Are farts really flammable?
Some people’s are. Glenn Gibson, who builds working models of the human colon at the University of Reading, UK, says all farters fall into one of two groups, “smelly” or “inflammable”. About a third of us are in the latter camp, with methane-producing bacteria in our bowels acquired from our mothers.
Methane, otherwise known as natural gas, is odourless and highly combustible. In fact, at concentrations above 4 or 5 per cent, it is explosive, so it’s fortunate that the act of passing wind mixes it with air, diluting the methane to safe levels. Place a match close enough to the source, however, and the seemingly innocuous flatus of an “inflammable” can be made to ignite.
Is it better out than in?
Every day, your gut generates a whopping 20 litres or more of gas. But most of this is not destined to become flatus: almost all of it is either recycled by the bacteria in your colon or absorbed into your body and exhaled in your breath.
For the bit that remains, there is evidence that smelly hydrogen sulphide prevents inflammation of the gut lining, maybe reducing your risk of bowel disease and cancer. So perhaps it might actually be good to hold that fart in. Gibson is sceptical, however. “Hydrogen sulphide is as toxic as cyanide,” he says. “Get rid of it.”
What’s to be done?
Well, there are products that contain the same enzymes used by the bacteria in your colon. Take one with your festive lunch and it will get to work straight away, breaking down the complex carbohydrates into simpler sugars that are more easily digested in the small intestine.
If it’s not wind but the nasty niffs that bother you, Levitt has found that bismuth can help, and there are stomach-remedy products available that contain it. However, a daily dose is not recommended because they can irritate the gut. And stay away from those charcoal knickers advertised on international flights: for all their promise, they’re full of hot air.
In any case, the experts agree that for most of us, flatus is nothing to worry about – a “blessing in disguise” that indicates you have healthy gut bacteria. Besides, is there a better butt for a joke than a fart?
(Image: Modern Toss)
This article appeared in print under the headline “Clearing the air”

More on these topics: More

WHATEVER you’re celebrating, the holidays are a good excuse to eat, drink and make merry. Flatulence is one of the most immediate consequences of overindulging and a perennial topic of mirth. But it also raises genuine questions that you’re probably too embarrassed to ask. We’re here to help.
Read more: Find all our holiday long reads here
Are some foods fartier than others?
Beans are not the only musical foods: flatus happens when we eat any complex carbohydrates. They are abundant in beans and pulses, but are also found in fruit and vegetables, dairy products, meat, alcoholic beverages and other goodies (yes, that’s practically everything – the list of foods that can reduce your toots is short and filled with caveats).
“Joseph Pojul made a career entertaining theatregoers with his fartistry”Advertisement
These compounds cannot be broken down in the small intestine, where most foods are digested, so pass unadulterated into the colon. Here, they are set upon by some 2 kilograms of bacteria, including the deceptively cuddly sounding Firmicutes and Bacteroidetes, which ferment the recalcitrant foodstuffs. The inevitable by-product is gas.
Gut microbes are particularly perky when you indulge in festive meals, largely due to the glut of carbohydrates. However, turkey with all the trimmings packs a double punch. Brussels sprouts, onions, dried fruit, red wine and the bird all contain sulphates, which are the key component of the most noxious intestinal gases.
How much wind is normal?
This is a tough one because you have to rely on honest answers. Studies asking volunteers to monitor their own emissions suggest 10 to 20 toots a day is normal. However, Terry Bolin at the University of New South Wales, Australia, found that men let rip an average of 12 times a day to women’s seven – which may result from a female tendency to suppress emissions.
In keeping with such wide variations, other research indicates that healthy people pass between 0.4 and 2.5 litres of gas daily. Not all of this is food-induced, though. About half the total volume derives from swallowed gases. Still, what you eat makes a huge difference, so much so that regular punters given a “flatulogenic diet” have been found to produce two-and-a-half times as much gas “per anus” as they do on their normal diet.
What’s in a fart?
Even the untrained nose can ascertain that the composition of flatus is highly variable. The percentage of swallowed gas can be far higher for people with ill-fitting dentures or an addiction to fizzy drinks. These gases are mainly nitrogen and oxygen. The remainder, produced by gut bacteria, is mostly hydrogen, along with carbon dioxide and methane.
So what makes the stink?
As in any perfume, the aroma comes from tiny quantities of pungent molecules. Flatulence guru Michael Levitt at the University of Minnesota, Minneapolis, has traced its noxiousness to three sulphurous gases, which together account for less than 1 part in 10,000 of an expulsion of wind. With help from two stalwart “odour judges”, he discovered that a fart’s potency derives from hydrogen sulphide, the “rotten-egg” gas. The overall bouquet, however, depends on how this intermingles with two other main culprits: methanethiol, which smells of “decomposing vegetables”, and the “sweet” odour of dimethyl sulphide.
Are silent ones deadlier?
Although sometimes described as a “bottom burp”, a fart is more like a whistle. The greater the volume and pressure of air passing through your rear, the louder the noise. This “instrument” has been played to considerable effect by professional trumpers, most notably the Frenchman “Le Pétomane”, aka Joseph Pojul, who from 1887 made a career entertaining theatregoers with his fartistry. Pojul had taught himself to suck up air through his anus and expel it under pressure to create farts that were thunderous but fairly innocuous.
By contrast, low volume and pressure give rise to a more discreet trump. But is it more noxious? Perhaps. Levitt found that women’s flatus contained significantly more pungent hydrogen sulphide than men’s, and his judges rated it as smellier.
Women also tend to produce less flatus than men, perhaps because of suppression – suggesting they are also more likely to control the pressure of their emissions to avoid drawing attention. This logic hints that a fart’s bark may indeed be inversely correlated with its bite.
Are farts really flammable?
Some people’s are. Glenn Gibson, who builds working models of the human colon at the University of Reading, UK, says all farters fall into one of two groups, “smelly” or “inflammable”. About a third of us are in the latter camp, with methane-producing bacteria in our bowels acquired from our mothers.
Methane, otherwise known as natural gas, is odourless and highly combustible. In fact, at concentrations above 4 or 5 per cent, it is explosive, so it’s fortunate that the act of passing wind mixes it with air, diluting the methane to safe levels. Place a match close enough to the source, however, and the seemingly innocuous flatus of an “inflammable” can be made to ignite.
Is it better out than in?
Every day, your gut generates a whopping 20 litres or more of gas. But most of this is not destined to become flatus: almost all of it is either recycled by the bacteria in your colon or absorbed into your body and exhaled in your breath.
For the bit that remains, there is evidence that smelly hydrogen sulphide prevents inflammation of the gut lining, maybe reducing your risk of bowel disease and cancer. So perhaps it might actually be good to hold that fart in. Gibson is sceptical, however. “Hydrogen sulphide is as toxic as cyanide,” he says. “Get rid of it.”
What’s to be done?
Well, there are products that contain the same enzymes used by the bacteria in your colon. Take one with your festive lunch and it will get to work straight away, breaking down the complex carbohydrates into simpler sugars that are more easily digested in the small intestine.
If it’s not wind but the nasty niffs that bother you, Levitt has found that bismuth can help, and there are stomach-remedy products available that contain it. However, a daily dose is not recommended because they can irritate the gut. And stay away from those charcoal knickers advertised on international flights: for all their promise, they’re full of hot air.
In any case, the experts agree that for most of us, flatus is nothing to worry about – a “blessing in disguise” that indicates you have healthy gut bacteria. Besides, is there a better butt for a joke than a fart?
(Image: Modern Toss)
This article appeared in print under the headline “Clearing the air”

Topics: More

Video: How to get drunk by eating food

I LOVE cooking with wine. Sometimes I even put it in the food.
Ah, the old ones are the best. But here’s an oldie that is well past its sell-by date: if you cook with wine, all the alcohol is “burned off” by the heat.
When I started telling people about my plan to see if I could eat myself drunk, I heard this piece of kitchen folklore again and again. And no wonder: it seems so plausible. The boiling point of ethanol is about 78.5 °C, significantly lower than the boiling point of, say, a casserole. So if you add wine to a hot pan, the alcohol evaporates.Advertisement
Read more: Find all our holiday long reads here
Not so. In 1992, a team of food scientists at the University of Idaho put this old chestnut to the test. They created several different booze-laden recipes, each with a different method of adding alcohol, and tested how much was left at the end. The answer ranged from “not much” to “most of it” – but all the recipes, including a casserole cooked for two-and-a-half hours, retained some alcohol.
This got me thinking: is it possible to get drunk only by eating things? If I ate a helping of, say, coq au vin followed by peaches in brandy, could I get pie-eyed? Not falling-down drunk, but legally drunk, which in England means being over the drink-drive limit of 80 milligrams of alcohol per 100 millilitres of blood, or a blood alcohol concentration of 0.08 per cent (see map).

Herein lies the serious side of my experiment. If cooked foods retain alcohol, people need to be careful – especially around Christmas. If a helping of casserole or a slice of Christmas cake contains even a few millilitres of alcohol, then eating it may be enough to push a careful but not totally abstemious driver onto the wrong side of the law.
The first thing I had to find out was how much I needed to drink to get over the limit. So I bought a breathalyser and set to work.
Can this man hold his drink?David Stock
For my first attempt I went to the pub, drank a pint of lager (5 per cent alcohol by volume), went back to my desk and waited. My breathalyser advises waiting at least 30 minutes before using it so the alcohol has cleared from your mouth, or else it upsets the reading. Half an hour later, I tested myself; the reading was 0.07 per cent, just below the limit.
The next day, I bought some beers on my way home and drank one before dinner. Half an hour later I breathalysed myself and found I was unfit to drive, with a blood alcohol level of 0.09 per cent – a bit of a surprise because I had drunk less than the day before. But other circumstances, such as food consumption, the environment in which you drink and even your mood can influence the rate at which the alcohol is absorbed. I drank another couple of beers just to make sure, but forgot to test myself again because I was watching reruns of Man v. Food.
In the end, I calculated it would take around 25 millilitres of alcohol (2.5 units) in liquid format to push me over the drink-drive limit. Would that also hold for alcohol in food?
Perhaps this innocent looking meal can get you drunk?David Stock
It quickly became clear that I could do it the easy way or the hard way. The easy way would involve a lunch of vodka jelly, liqueur chocolates and other things that are really just booze masquerading as food. The hard way would involve cooking, and then eating, a lot of food with quite low levels of alcohol in it. I chose the hard way.
My colleagues, who I turned to for menu suggestions, weren’t much help. Most said “don’t bother, the alcohol will all have burned off” (where have you been?). Lots of them came up with items on the banned list. Vodka gazpacho sounded promising until I realised that it is basically a Bloody Mary and hence not food. One colleague told me about a Jamaican cake called “black cake” that is apparently so potent it can knock out a horse, but it took too long to make.
And so I asked Google. Google was really helpful. It led me, among other things, to a study carried out in 2011 that tested various dishes for alcohol retention and, helpfully, included a recipe for fish simmered in white wine. My search also alerted me to the idea of flambéing chorizo, and led to a recipe for a cake so boozy that you could probably use it as an incendiary device.
The final menu (see below) was designed to deliver about 30 millilitres of alcohol; I was confident of making it over the line as long as I could manage to eat everything – though I bought a box of liqueur chocolates just in case.
Did I make it? Yes and no. The starter instantly tipped me over the drink-drive limit. That fits with the surprising finding that one of the least efficient methods of getting rid of ethanol is flambéing, with 75 per cent left after the flames go out. Although the potent effect may also have been because I breathalysed myself too soon, when my mouth was still awash with brandy.
After the main course I was still over the limit, though less so. According to the fish study, cooking the dish this way retains around 30 per cent of the alcohol. That’s because alcohol forms what is called an azeotropic mixture with water, in which the vapour has the same alcohol/water ratio as the liquid. In other words, boiling the mixture doesn’t change the ratio – so it is impossible to boil the alcohol off completely. The dish should have added to my previous tipsiness, but perhaps the potatoes washed some of the brandy out of my mouth.
The trifle was another instant lawbreaker, pushing the breathalyser over its detection threshold (which was more than twice the drink-drive limit) and the cake – which in true seasonal style I forced down despite being full – kept it there. I’m not sure whether that was down to alcohol in my mouth or my bloodstream. But I felt distinctly drunk and would not have driven.
I even ate one of the emergency chocolates. OK, two.
Half an hour after finishing, I was hovering around the limit. After an hour I was safely back under it (though I would still have been unfit to drive in many countries because the UK has some of the laxest drink-drive laws in the world). But I think my point has been made: even if you don’t drink any alcohol, food can push you over the legal limit. So if you do have a drink and are expecting to drive home, be careful what you eat. And next time somebody tells you that cooking with wine burns the alcohol off, tell them about the man who ate himself pissed.

Alcohol retained in cooked food
85% If alcohol is added to boiling liquid then taken off heat
75% Flambéed
70% No heat, stored overnight
Alcohol stirred into mixture then baked/simmered for:15 minutes = 40%30 minutes = 35%1 hour = 25%1.5 hours = 20%2 hours = 10%2.5 hours = 5%

Menu
STARTER: Chorizo flambéed in brandyAlcohol added: 45 ml brandy, 36% ABVMethod: flambéAlcohol retention: 75 per centEthanol consumed: 12.15 ml
MAIN: Fish in white wineAlcohol added: 180 ml wine, 12% ABVMethod: simmer, 30 minutesAlcohol retention: 35 per centEthanol consumed: 7.56 ml
DESSERT: Sherry trifle with syllabub toppingAlcohol added: 275 ml sherry, 17% ABV45 ml brandy, 36% ABVMethod: no heat, refrigeratedAlcohol retention: 70 per centEthanol consumed: approx 6 ml per portion
DESSERT 2: Long Island Iced Tea cakeAlcohol added: 255 ml spirits, 40% ABVMethod: baked, 30 minsAlcohol retention: 35 per centEthanol consumed: approx 4.5 ml per slice
EMERGENCY LIQUEUR CHOCOLATESApproximately 0.06 ml alcohol per chocolate

This article appeared in print under the headline “Eat yourself drunk”

Topics: More