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Why Can't Elephants Jump?
And 113 Other Tantalizing Science Questions Answered
By New Scientist
Pegasus Books LLCCopyright © 2011 New Scientist Magazine
All rights reserved.
Food and drink
Is there a single foodstuff that could provide all the nutrients that a human needs to stay reasonably healthy indefinitely?
Any single substance such as water or fat? No. Any single tissue such as muscle or potato? No. But if we allow free drinking water and air to breathe – even though those are also nutrients – then we can relax our rules. Even so, drinking milk while eating corn would count as two foodstuffs, and who knows how many foodstuffs pizza contains.
Not surprisingly, no strict monodiet can rival any healthily balanced diet, but there are two classes of foodstuffs that in appropriate quantities can maintain a reasonable level of health. One such class is baby food. Examples include eggs, milk, certain seeds, and so on. None is a perfect option, but some are adequate.
Alternatively one might cheat by counting essentially whole animals: oysters or fish such as whitebait or sardines might supply the necessary nutrient uptake. Animals sufficiently closely related to humans might also do, if eaten in the correct form and quantity. Farming families in the semidesert Karoo region of South Africa apparently ate mainly sheep or cattle.
For the most perfectly balanced human monodiet, however, other humans would be the logical food of choice. Not sure there would be many takers though.
Somerset West, South Africa
Despite various claims made over the years for spinach, baked beans or bananas, the answer is 'no'. To remain healthy over the course of a natural lifetime, a human needs a balanced diet, with a combination of carbohydrates and protein and a proper range of vitamins. The balance may vary with age, from individual to individual, and even between societies in differing environments, but balance is the key to healthy eating.
Probably the most homogenous diet of any human community is that of the Inuit in Arctic North America, which traditionally consists of 90 per cent meat and fish and effectively no carbohydrates. The explorer Vilhjalmur Stefansson not only established that Inuit hunters often lived for between six and nine months of the year on a wholly carnivorous diet, but also claimed to have sustained himself by eating just meat and fish on his expeditions.
In a series of controlled experiments under the auspices of The Journal of the American Medical Association, Stefansson and a number of his colleagues reproduced the dietary regime they had followed in the Arctic, without any apparent ill effects and without, much to the supervising doctors' surprise, developing scurvy. However, subsequent long-term studies of health factors in the Inuit community have established a strong correlation between the carnivorous diet and early deaths among Inuit men from heart attacks and other cardiac problems.
The bottom line is to remember what your mother told you: always eat your greens.
Norwich, Norfolk, UK
Humans have been suggested as the ideal diet for other humans, but eating human flesh would not satisfy all our dietary needs, no matter how healthy the diner or victim, for a very simple reason: not every nutrient, mineral and vitamin in the body remains available to the next step in the food chain. Some substances are 'used up' and others are built into indigestible tissues and structures.
Cooking can increase the digestibility of many foodstuffs for a human, but things like hair, bones and teeth cannot be prepared to make them amenable to our digestion. However, we need the minerals, amino acids and other nutrients in them to make these substances for ourselves.
The human body is a tenacious machine and will continue to survive on a very poor diet for quite a while. Many people living in harsh climates have their own dietary supplements in local foods and 'delicacies' that they may not even realise are making up a shortfall. The same is true of those who live in a self-imposed harsh regime, such as true vegetarians. One can live on such diets and remain healthy as long as there is a balanced variety of nutrients, or by taking artificial supplements such as vitamin B12.
Some natural foodstuffs provide a reasonable balance of necessary nutrients, but the only known and proven foodstuffs that truly provide everything that a human body would need, in a single wrapper, are manufactured. Survival rations and trail foods are many and varied, but remain unpopular because they are generally dry and unpalatable.
Foods made to cover all the needs of large and physiologically similar mammals, such as dogs, pigs and other omnivores, could probably sustain us very well too, although we may have to eat more of the stuff than we'd like to get sufficient supplies of any human-specific nutrients.
By email, no address supplied
What is the significance of James Bond's famous phrase 'shaken, not stirred'? Is there really a difference in the taste of a shaken vodka martini, as opposed to a stirred one? And if so, why?
Stockport, Cheshire, UK
The dispute over the difference between a shaken or stirred martini has run for some years in the Last Word. An earlier book in this series, How to Fossilise Your Hamster, drew on the following three answers to explain the differences. However, more information has come to light – Ed.
Supposedly, when a martini is shaken, not stirred, it 'bruises' the spirit in the martini. To seasoned martini drinkers this changes the taste.
Newcastle, New South Wales, Australia
Because a martini is to be drunk within seconds of preparation rather than minutes, there is a difference. The tiny bubbles caused by the shaking mean that a well-shaken martini is cloudy. This will also have an effect on the texture of the drink – it is less oily than the stirred version – hence the taste. The long-standing assumption that the spirit is bruised by the process is nonsense because vodka does not have a vascular system.
James Bond may have appreciated the softening and ripening effect of partial oxidation of the aldehydes in vermouth – akin to letting red wine breathe before drinking. In a refined and homogeneous substrate such as vodka martini, a good shake can speed the process.
Bishops Stortford, Hertfordshire, UK
We have since learned, however, that other chemical reactions may be taking place – Ed.
Biochemists at the University of Western Ontario in Canada have suggested that the change in flavour is not caused by the oxidation of aldehydes, but because shaking martinis can break down hydrogen peroxide present in the drink. Stirred martinis have double the amount of hydrogen peroxide that shaken ones contain. This significantly affects the flavour.
Vancouver, British Columbia, Canada
The reason that shaken martinis are cloudy is not so much down to bubble formation from the cocktail-shaking process but rather that the crushed ice used in the shaker deposits tiny crystals into the poured drink. These make the drink more cloudy and then slowly melt, allowing it to clear.
New York City, US
This clearly called for more research. Was it bubbles or ice that caused the cloudiness in a shaken martini? And could either account for any difference in taste? First up we needed a good martini recipe. This one came from cocktail mixologist Eric Keitt, who works the bar at Oceanaire in Washington DC:
Double vodka and a few drops of dry vermouth
Pour into a cocktail shaker with crushed ice
Shake until the hand holding the shaker is very cold
Strain into a martini glass
Add an olive or a twist of lime zest
Eric tells us: 'The application of vermouth should be a few – and I mean a few – drops, maybe two or three. Vermouth will release the aromatics of the vodka, making for a more enjoyable drink.' Eric is a fan of stirring the drink for the reasons given below, but in this instance we had no choice but to shake.
Three martinis were prepared. The first was shaken with crushed ice. The drink was very cloudy and took a long time to clear but, as far as we could ascertain, the cloudiness was caused only by tiny bubbles from the shaking plus the condensation on the chilled martini glass. No ice crystals were present unless they were microscopic.
The second was a room-temperature martini, shaken without ice. Bubbles formed in this when it was poured but quickly dissipated, much faster than in the iced martini.
The third martini was made in an attempt to replicate the chilled conditions of the iced martini but without adding ice to the shaker. The martini and its shaker were wrapped in a drinks chiller until ice cold and the same temperature as the first martini. Then it was shaken. When poured it was cloudy for much longer than the room-temperature martini but not for as long as the iced martini.
From this we ascertained that the ice does have some effect on the clouding process, as do cold conditions. Iced martinis do produce the cloudiest drink, but no ice spicules appeared present in the drink, contrary to the suggestion above by Frank Melly. Chilled martinis without ice produced a cloudy drink too, but for a shorter time than iced martinis. The room-temperature martini cleared the fastest. So nothing conclusive here yet, except that temperature plays a role of some kind – more experimentation is needed. Is there any reader out there who can examine the shaken martini microscopically to rule out (or, indeed, confirm) the presence of ice crystals?
But there's more. Putting cloudiness to one side for the moment, Anna Collins seems to have answered the original question of what makes a shaken martini taste different to a stirred one, her suggestion apparently being confirmed in a blind tasting – Ed.
The reason Bond orders his martinis shaken is that the ice helps to dissipate any residual oil left over in the manufacture of vodka from potatoes – the base vegetable for many vodkas at the time Ian Fleming's original novels were written. With the rise of higher quality grain vodkas the process is now unnecessary. In fact, shaking the martini with ice dilutes it too much for many fans of the drink. Stirring chills the martini without losing its essential strength.
Washington DC, US
Anna Collins is correct, according to our blind trial. We bought two bottles of vodka, one grain based, the other potato based. First we tasted the vodkas. In the blind trial all six people in our sample said the potato vodka was oily, the grain vodka wasn't. Then we made two vodka martinis using the potato vodka. One was stirred with ice, the other shaken with ice. The difference was quite distinct and in a blind tasting every one of the six drinkers correctly identified the shaken martini as being much less oily. But the martini had to be consumed quickly. If left to settle for about 5 minutes or so, the shaken martini became oily again.
Maybe that's the last word on vodka martinis. Although knowing our readers' propensity to keep unearthing new evidence, we suspect not – Ed.
Having discovered the joys of the 'appletini' (vodka mixed with apple juice, cider or apple liqueur), I have a question. The garnish is a slice of apple and a Maraschino or glacé cherry on a cocktail stick. If the cherry is at the bottom of the stick it floats in the appletini, but with the apple slice at the bottom it sinks. Why? Surely the buoyancy of the two items combined is an absolute and their orientation should make no difference. I shall leave it to the imagination as to the number of 'tinis consumed before this anomaly became a burning topic of conversation.
St Saviour, Jersey
Ethanol acts as a wetting agent, so in an alcoholic drink the submerged slice of apple holds too little air to float the non-buoyant, sugary cherry. The assembly will thus sink, though if you add soda, enough bubbles might attach to the apple to make the whole thing float again.
Human sloshing complicates insights after the fourth glass of appletini, but buoyancy is a more complicated affair than density considerations might suggest. For example, a boat that is seaworthy might sink if capsized.
Try dropping a clean, dry pin or razor blade gently onto a glass of still, pure water. Dropped endwise the object sinks; the metal is too dense. But surface tension will support the item if you gently drop it flat onto the fluid, especially if the metal is lightly waxed or oiled.
The behaviour of your appletini garnish is similar in some ways. The waxy skin and the broad shape of an unpeeled slice of apple on the surface of the drink can resist both the wetting and the shipping of fluid over the edge of the slice.
The stimulation of considering this question's complications should mitigate the brainaddling aspects of appletini, though, sadly, not to the extent of fully reversing them.
Surface tension effects probably account for the observations. If the buoyancy of the cocktail stick assembly is nearly neutral, a flat slice of apple, when uppermost and level with the cocktail surface, may provide a sufficiently long perimeter for surface tension to hold the assembly up. The spherical cherry in the same position has little or no perimeter on which surface tension can act. The coating on the cherry may also reduce surface tension.
Try replacing the apple slice with a small ball of apple and see if the stick now sinks even with the apple uppermost. If this experiment fails, the cocktail may have aged, so drink it and try again with a new one ...
Northwich, Cheshire, UK
Hot to trot
Mustard and chillies are both hot, but the burning sensation from a chilli stays in the mouth for ages while the sensation from hot mustard disappears in a few seconds. Why is this?
By email, no address supplied
The chemical mainly responsible for the burning spice in chilli peppers is capsaicin, a complicated organic compound that binds to receptors in your mouth and throat, producing the desired (or dreaded) sensation.
Capsaicin is an oil, almost completely insoluble in water. This is why you need a fat-containing substance like milk to wash it away – watery saliva doesn't do the trick.
On the other hand, the compound responsible for the hotness of mustard (as well as horseradish and wasabi) is called allyl isothiocyanate. This chemical is slightly water-soluble, and can be more readily washed away into the stomach by saliva.
Further, the chemical in mustard is more volatile than capsaicin so it evaporates more readily, allowing its fumes to enter the nasal passages (explaining why the burning sensation from mustard is often felt in the nose). These fumes can be easily removed by breathing deeply, a useful strategy if the sensation becomes overwhelming.
The hotness of mustard comes from allyl isothiocyanate, which is formed when myrosinase and sinigrin (in mustard seeds) react together in water. It dissolves well in most organic compounds, and to an extent in water, and is also volatile, so will quickly disperse.
On the other hand, capsaicin, the hot ingredient of chillies, is not very water-soluble. So its heat tends to stay. It is soluble, however, in alcohol, which raises the question: which came first, the lager or the vindaloo?
We are constantly being exhorted to eat five servings of fruit or vegetables a day, cut down on red meat, eat more fish and so on. But very little of this advice mentions that other kingdom of gastronomic delights, fungi. What nutritional value does your average edible fungus have?
Until recently the village of Bourré in central France, where I live, was a major production centre for mushrooms. Now all we have left is an artisanal operation as a tourist attraction.
However, the two kinds of mushrooms that were the mainstays of the industry are still produced here: Agaricus bisporus, or champignon de Paris, which in English tends to be simply called a 'mushroom'; and Lentinula edodes, the shiitake mushroom. The former has slightly more than 3 grams of protein per 100 grams, and a range of trace minerals including calcium, iron, magnesium, phosphorus, potassium, zinc, copper and manganese. It also contains vitamin C and several B vitamins. Shiitake mushrooms contain rather more zinc but are lower in protein and vitamin C.
Excerpted from Why Can't Elephants Jump? by New Scientist. Copyright © 2011 New Scientist Magazine. Excerpted by permission of Pegasus Books LLC.
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