Scientists now believe that human beings acquired the sense of taste as a way to avoid being poisoned. Edible plants generally taste sweet; deadly ones, bitter. Taste is supposed to help us differentiate food that’s good for us from food that’s not. The taste buds on our tongues can detect the presence of half a dozen or so basic tastes, including sweet, sour, bitter, salty, and umami (a taste discovered by Japanese researchers, a rich and full sense of deliciousness triggered by amino acids in foods such as shellfish, mushrooms, potatoes, and seaweed). Tastebuds offers a limited means of detection, however, compared with the human olfactory system, which can perceive thousands of different chemical aromas. Indeed, ‘flavor’ is primarily the smell of gases being released by the chemicals you’ve just put in your mouth. The aroma of food can be responsible for as much as 90% of its flavor.

 The act of drinking, sucking or chewing a substance releases its volatile gases. They flow out of the mouth and up the nostrils, or up the passageway at the back of the mouth, to a thin layer of nerve cells called the olfactory epithelium, located at the base of the nose, right between the eyes. The brain combines the complex smell signals from the epithelium with the simple taste signals from the tongue, assigns a flavor to what’s in your mouth, and decides if it’s something you want to eat.

 Babies like sweet tastes and reject bitter ones; we know this because scientists have rubbed various flavors inside the mouths of infants and then recorded their facial reactions. A person’s food preferences, like his or her personality, are formed during the first few years of life, through a process of socialization. Toddlers can learn to enjoy hot and spicy food, bland health food, or fast food, depending upon what the people around them eat. The human sense of smell is still not fully understood. It is greatly affected by psychological factors and expectations. The mind filters out the overwhelming majority of chemical aromas that surround us, focusing intently on some, ignoring others. People can grow accustomed to bad smells or good smells; they stop noticing what once seemed overpowering.

 Aroma and memory are somehow inextricably linked. A smell can suddenly evoke a long-forgotten moment. The flavours of childhood foods seem to leave an indelible mark, and adults often return to them, without always knowing why. These ‘comfort foods’ become a source of pleasure and reassurance a fact that fast-food chains work hard to promote Childhood memories of Happy Meals can translate into frequent adult visits to McDonald’s’, like those of the chain’s ‘heavy users’, the customers who eat there four or five times a week.

 The human craving for flavour has been a large unacknowledged and unexamined force in history. Royal empires have been built, unexplored lands have been traversed, great religions and philosophies have been forever changed by the spice trade. In 1492, Christopher Columbus set sail in order to try to find new seasonings and thus to make his fortune with this most desired commodity of that time. Today, the influence of flavour in the world marketplace is no less decisive. The rise and fall of corporate empires – soft-drink companies, snack-food companies, and fast-food chains – is frequently determined by how their products taste.

 The flavor industry emerged in the mid-1800s, as processed foods began to be manufactured on a large scale. Recognizing the need for flavor additives, the early food processors turned to perfume companies that had years of experience working with essential oils and volatile aromas. The great perfume houses of England, France, and the Netherlands produced many of the first flavor compounds. In the early part of the 20th century, Germany’s powerful chemical industry assumed the lead in flavour production. Legend has it that a German scientist discovered methyl anthranilate, one of the first artificial flavours, by accident while mixing chemicals in his laboratory. Suddenly, the lab was filled with the sweet smell of grapes. Methyl anthranilate later became the chief flavoring compound of manufactured grape juice.

The quality that people seek most of all in a food, its flavour, is usually present in a quantity too infinitesimal to be measured by any traditional culinary terms such as ounces or teaspoons. Today’s sophisticated spectrometers, gas chromatograph, and headspace vapor analyzers provide a detailed map of a food’s flavour components, detecting chemical aromas in amounts as low as one part per billion. The human nose, however, is still more sensitive than any machine yet invented. A nose can detect aromas present in quantities of a few parts per trillion. Complex aromas, such as those of coffee or roasted meat, may be composed of gases from nearly a thousand different chemicals. The chemical that provides the dominant flavour of bell pepper can be tasted in amounts as low as 0.02 parts per billion; one drop is sufficient to add flavour to the amount of water needed to fill five average-sized swimming pools

 Telecommuting, Internet shopping and online meetings may save energy as compared with in-person alternatives, but as the digital age moves on, its green reputation is turning a lot browner. E-mailing, number crunching and Web searches in the U.S. consumed as much as 61 billion kilowatt-hours last year, or 1.5 per cent of the nation’s electricity-half of which comes from coal. In 2005 the computers of the world ate up 123 billion kilowatt-hours of energy, a number that will double by 2010 if present trends continue, according to Jonathan Koomey, a staff scientist at Lawrence Berkeley National Laboratory. As a result, the power bill to run a computer over its lifetime will surpass the cost of buying the machine in the first place giving Internet and computer companies a business reason to cut energy costs, as well as an environmental one.

 One of the biggest energy sinks comes not from the computers themselves but from the air-conditioning needed to keep them from overheating. For every kilowatt-hour of energy used for computing in a data centre, another kilowatt-hour is required to cool the furnace-like racks of servers.

 For Internet giant Google, this reality has driven efforts such as the installation of a solar array that can provide 30 per cent of the peak power needs of its Mountain View, Calif., headquarters as well as increased purchases of renewable energy. But to deliver Web pages within seconds, the firm must maintain hundreds of thousands of computer servers in cavernous buildings. “It’s a good thing to worry about server energy efficiency,” remarks Google’s green energy czar Bill Weihl. “We are actively working to maximize the efficiency of our data centres, which account for most of the energy Google consumes worldwide.” Google will funnel some of its profits into a new effort, dubbed RE

 In the meantime, the industry as a whole has employed a few tricks to save watts. Efforts include cutting down on the number of transformations the electricity itself must undergo before achieving the correct operating voltage; rearranging the stacks of servers and the mechanics of their cooling; and using software to create multiple “virtual” computers, rather than having to deploy several real ones. Such virtualization has allowed computer maker Hewlett-Packard to consolidate 86 data centers spread throughout the world to just three, with three backups, says Pat Tiernan, the firm’s vice president of social and environmental responsibility.

 The industry is also tackling the energy issue at the computer-chip level. With every doubling of processing power in recent years has come a doubling in power consumption. But to save energy, chipmakers such as Intel and AMD have shifted to so-called multicore technology, which packs multiple processors into one circuit rather than separating them. “When we moved to multicore-away from a linear focus on megahertz and gigahertz—and throttled down microprocessors, the energy savings were pretty substantial,” says Allyson Klein, Intel’s marketing manager for its Ecotech Initiative. Chipmakers continue to shrink circuits on the nanoscale as well, which means a chip needs less electricity” to deliver the same performance, she adds.

 With such chips, more personal computers will meet various efficiency standards, such as Energy Star compliance (which mandates that a desktop consume no more than 65 watts). The federal government, led by agencies such as NASA and the Department of Defense may soon require all their purchases to meet the Electronic Product Environmental Assessment Tool standard. And Google, Intel and others have formed the Climate Savers Computing Initiative, an effort to cut power consumption from all computers by 50 per cent by 2010.

 Sleep modes and other power management tools built into most operating systems can offer savings today. Yet about 90 per cent of computers do not have such settings enabled, according to Klein. Properly activated, they would prevent a computer from leading to the emission of thousands of kilograms of carbon dioxide from power plants every year. But if powering down or unplugging the computer (the only way it uses zero power) is not an option, then perhaps the most environmentally friendly use of all those wasted computing cycles is in helping to model climate change. The University of Oxford’s ClimatePrediction.net offers an opportunity to at least predict the consequences of all that coal burning.

CO2 Stats is a free tool that can be embedded into any Website to calculate the carbon dioxide emissions associated with using it. That estimate is based on an assumption of 300 watts of power consumed by the personal computer, network and server involved- or 16.5 milligrams of CO2 emitted every second of use. “The typical carbon footprint is roughly equivalent to 1.5 people breathing,” says physicist Alexander Wissner-Gross of Harvard University, who co-created the Web tool.