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Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format. New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address. THE LAST WORD Catching the red-eye Some bird species, such as the great-crested grebe, hunt underwater for fish and have red eyes. The red colouring is presumably beneficial to these diving birds, but in what way? If it does provide an advantage, why have other birds with similar habits not evolved red eyes? n The red eye is caused by the colour of the iris, which controls the diameter of the pupil. Only some diving birds have red irises. The pigmentation of the iris is just a device for making the iris as opaque as possible to accurately control the amount of light reaching the retina, by ensuring no light leaks through the iris muscles. Its colour is in this sense irrelevant. But eye colour was extensively reviewed by ophthalmologist Ida Mann in 1931, who concluded that iris colour is used as a signal between animals. There has been no evidence to counter this conclusion since. So that a structure used for signalling is conspicuous, it needs to contrast with its surroundings, and so bright iris colours often contrast strongly with the feather or skin of the head in birds (or, in certain cases, they match it). Eye colour varies widely. There are grebes with yellow eyes, penguins with black, red or yellow eyes, and cormorants with blue, green, red or black eyes. Iris colour changes with age in many birds, with the young showing only browns and blacks and not attaining the full bright colour until adulthood. Presumably this is when they need to use iris colour as a signal of fitness or when emotional state becomes important. Graham Martin Emeritus Professor Centre for Ornithology School of Biosciences University of Birmingham, UK Stirring stuff 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? (Continued) n Anna Collins of Washington DC told us that the reason James Bond ordered his martinis shaken was that at the time the Bond novels were written, vodka was widely made from potatoes rather than grain, as is common today. Potato vodka is noticeably oily and shaking it with ice dissipates the oil. This was confirmed in a blind tasting by reader Peter Simmons, of London. However, another reader in the UK, William France of Birmingham, wrote in to point out that in the book and movie Casino Royale Bond orders his martini to the recipe later known as a vesper, which contains more gin than vodka, yet he still requests that it is shaken. So why? – Ed n Bond’s martini in Casino Royale is made to the following recipe with thanks to the 1953 novel by Ian Fleming: “A dry martini,” [Bond] said. “One. In a deep champagne goblet.” “Oui, monsieur.” “Just a moment. Three measures of Gordon’s [gin], one of vodka, half a measure of Kina Lillet. Shake it very well until it’s ice-cold, then add a large thin slice of lemon peel. Got it?” “Certainly, monsieur.” The barman seemed pleased with the idea. We can also presume the vodka used was a potato vodka because Bond goes on to tell the barman: “Excellent... but if you can get a vodka made with grain instead of potatoes, you will find it still better.” So we know there is a measure of potato vodka in the vesper. To check whether this still makes a difference to the martini, I and four friends repeated Peter Simmons’s blind tasting of the martinis, making one batch with potato vodka and another with grain. We had to amend the recipe slightly because the Kina Lillet in the vesper (which replaces the dry vermouth used in standard martinis) is no longer produced, the nearest modern-day product being Lillet Blanc. Lillet Blanc is less bitter than Kina Lillet (Kina referring to the bitter quinine that was in the original) so we had to add two drops of bitters to the drink so it matched the original vesper taste. Without a doubt, the potato vodka vesper was oilier than the grain vodka version (despite containing only a single measure of gin, as opposed to three). And subsequently when shaken with ice, the oil in the potato- vodka vesper was much less pronounced. All tasters were unanimous in detecting this. Thus, despite the modern convention of stirring martinis, it seems that Bond, a man of obvious sophistication, knew what he was talking about when always asking for his martinis to be shaken, recipe notwithstanding. Janice Devaney London, UK This week’s questions TASTEFUL PARADOX Why, when pressed garlic is put on roasting red pepper, does it turn bright turquoise? Rowan Hooper London, UK RIGHT WAY ROUND Do standard anticlockwise running tracks favour right- handed runners? Do right- handers win disproportionately more track events than left- handers? If not, why? Francisco Silva Madrid, Spain “James Bond knew what he was talking about when he asked for his martinis to be shaken, not stirred” Last words past and present, plus questions, at last-word.com The latest collection: witty, brilliant, intelligent and packed with insight Available from booksellers and at www.newscientist.com/elephants Why can’t elephants jump?
