READING PASSAGE 1 – Last man standing

Some 50,000 years ago, Homo sapiens beat other hominids to become the only surviving species. Kate Ravilious reveals how we did it. 

A Today, there are over seven billion people living on Earth. No other species has exerted as much influence over the planet as us. But turn the clock back 80,000 years and we were one of a number of species roaming the Earth. Our own species. Homo sapiens (Latin for ’wise man’), was most successful in Africa. In western Eurasia, the Neanderthals dominated, while Homo erectus may have lived in Indonesia. Meanwhile, an unusual finger bone and tooth, discovered in Denisova cave in Siberia in 2008, have led scientists to believe that yet another human population – the Denisovans – may also have been widespread across Asia. Somewhere along the line, these other human species died out, leaving Homo sapiens as the sole survivor. So what made us the winners in the battle for survival?

B Some 74.000 years ago, the Toba ‘supervolcano’ on the Indonesian island of Sumatra erupted. The scale of the event was so great that ash from the eruption was flung as far as eastern India, more than 2,000 kilometres away. Oxford archaeologist Mike Petraglia and his team have uncovered thousands of stone tools buried underneath the Toba ash. The mix of hand axes and spear tips have led Petraglia to speculate that Homo sapiens and Homo erectus were both living in eastern India prior to the Toba eruption. Based on careful examination of the tools and dating of the sediment layers where they were found. Petraglia and his team suggest that Homo sapiens arrived in eastern India around 78.000 years ago. migrating out of Africa and across Arabia during a favourable climate period. After their arrival, the simple tools belonging to Homo erectus seemed to lessen in number and eventually disappear completely. ‘We think that Homo sapiens had a more efficient hunting technology, which could have given them the edge.’ says Petraglia. ‘Whether the eruption of Toba also played a role in the extinction of the Homo erectus-like species is unclear to us.’

C Some 45.000 years later, another fight for survival took place. This time, the location was Europe and the protagonists were another species, the Neanderthals.

They were a highly successful species that dominated the European landscape for 300.000 years. Yet within just a few thousand years of the arrival of Homo sapiens, their numbers plummeted. They eventually disappeared from the landscape around 30.000 years ago. with their last known refuge being southern Iberia, including Gibraltar. Initially. Homo sapiens and Neanderthals lived alongside each other and had no reason to compete. But then Europe’s climate swung into a cold, inhospitable, dry phase. ‘Neanderthal and Homo sapiens populations had to retreat to refugia (pockets of habitable land). This heightened competition between the two groups,’ explains Chris Stringer, anthropologist at the Natural History Museum in London.

D Both species were strong and stockier than the average human today, but Neanderthals were particularly robust. ‘Their skeletons show that they had broad shoulders and thick necks,’ says Stringer. ‘Homo sapiens, on the other hand, had longer forearms, which undoubtedly enabled them to throw a spear from some distance, with less danger and using relatively little energy,’ explains Stringer. This long-range ability may have given Homo sapiens an advantage in hunting. When it came to keeping warm. Homo sapiens had another skill: weaving and sewing. Archaeologists have uncovered simple needles fashioned from ivory and bone alongside Homo sapiens, dating as far back as 35,000 years ago. ‘Using this technology, we could use animal skins to make ourselves tents, warm clothes and fur boots,’ says Stringer. In contrast. Neanderthals never seemed to master sewing skills, instead relying on pinning skins together with thorns.

E A thirst for exploration provided Homo sapiens with another significant advantage over Neanderthals. Objects such as shell beads and flint tools, discovered many miles from their source, show that our ancestors travelled over large distances, in order to barter and exchange useful materials, and share ideas and knowledge. By contrast. Neanderthals tended to keep themselves to themselves, living in small groups. They misdirected their energies by only gathering resources from their immediate surroundings and perhaps failing to discover new technologies outside their territory.

F Some of these differences in behaviour may have emerged because the two species thought in different ways. By comparing skull shapes, archaeologists have shown that Homo sapiens had a more developed temporal lobe – the regions at the side of the brain, associated with listening, language and long-term memory. ‘We think that Homo sapiens had a significantly more complex language than Neanderthals and were able to comprehend and discuss concepts such as the distant past and future.’ says Stringer. Penny Spikins, an archaeologist at the University of York, has recently suggested that Homo sapiens may also have had a greater diversity of brain types than Neanderthals.

‘Our research indicates that high-precision tools, new hunting technologies and the development of symbolic communication may all have come about because they were willing to include people with “different” minds and specialised roles in their society,’ she explains. ‘We see similar kinds of injuries on male and female Neanderthal skeletons, implying there was no such division of labour,’ says Spikins. 

G Thus by around 30,000 years ago. many talents and traits were well established in Homo sapiens societies but still absent from Neanderthal communities. Stringer thinks that the Neanderthals were just living in the wrong place at the wrong time. ‘They had to compete with Homo sapiens during a phase of very unstable climate across Europe. During each rapid climate fluctuation, they may have suffered greater losses of people than Homo sapiens, and thus were slowly worn down,’ he says. ‘If the climate had remained stable throughout, they might still be here.’

Reading Passage 2 – The Sense for flavour2

You should spend about 20 minutes on Questions 14-26 which are based on Reading Passage 3 below.

{A} 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.

{B} 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.

{C} 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.

{D} 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.

{E} 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.

{F} 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.

{G} 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.

Reading Passage 3 – Fueling The Future

You should spend about 20 minutes on Questions 27-40 which are based on Reading Passage 3.

A. The world’s 750 million motor vehicles emit well over 900 million metric tonnes of carbon dioxide each year. Traffic-related air pollution has been responsible for 6% of deaths per year and is associated with certain forms of leukaemia, inflammatory lung diseases, increased cardiovascular disease, low birth-weight babies and male infertility. It stands to reason that tackling traffic-related air pollution should be high on any government’s list of priorities. Thus, in an attempt to minimise this situation many governments around the world have been looking at ways to implement alternative fuel sources. The most widely accepted way of doing this is to replace the crude oil that our vehicles currently run on with renewable, ‘environmentally friendly^’One serious contender put forward as a solution to the pollution problem is ethanol. Ethanol is a type of alcohol made by fermenting plant material. Water and organic matter from the plants including com, sorghum, sugar cane and wood are mixed together and fermented to make ethanol.

B. After fermentation, there are three layers remaining. The first is water and small particles of grain and alcohol. It takes on a syrup consistency. The second layer is the remaining grain, which is 17 per cent dry matter. The third layer is the actual ethanol – a colourless, volatile, flammable liquid. It is the only layer sold and accounts for exactly one-third of the total dry matter used for its production. There are three primary ways that it is used as a fuel for transportation: as a blend of 10 per cent ethanol with 90% unleaded fuel (E10); as a component of reformulated gasoline and; as a primary fuel with 85 parts of ethanol blended with 15 parts of unleaded fuel (E-85). In the 1800s in the USA, it was first used as lamp fuel. Later on_,due to skyrocketing oil prices in the 1970s, E10 was produced as a type of ‘fuel-extender’ for vehicles with E-85 being produced in the 1990s. Brazil has also used ethanol-blended fuels. Like America, the high prices in the 1970s prompted a government mandate to produce vehicles which could be fuelled by pure ethanol Today there are more than 4,2 million ethanol-powered vehicles in Brazil (40 per cent passenger-carrying) which consume 4 billion gallons of ethanol annually. Today, Brazil is the largest transportation ethanol fuel market in the world.

C. Given that Ethanol is made from a variety of plant substances when it is used in fuel production, it increases the monetary value of feed grains grown by farmers. In fact, in the USA, the largest ethanol consuming nation in the world, ethanol production adds £4.5 billion to the farm economy every year. According to the United States Department of Agriculture, ethanol production adds 30 cents to the value of a bushel of corn. Another of its benefits, according to Brian Keating, deputy chief of Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) is that a 10% ethanol blend (E10) would reduce greenhouse gas emissions by 2 to 5% over the full lifecycle of ethanol production and consumption. Said Keating, “The precise benefits depend on specific factors in the production cycle. An important component of which is the energy source used by the ethanol factory. If it’s being powered by coal or oil, there are obviously associated with greenhouse gas emissions.” In America, The Clean Air Act of 1990 and the National Energy Policy Act of 1992 have both created new market opportunities for a cleaner, more efficient fuels with many state governments in America’s Mid-west purchasing fleet vehicles capable of running on E-85 fuels.

D. Although it makes a good fuel, some drawbacks have been documented. The economics of ethanol production are improving as the technology improves but ethanol has two problems: It does not explode like gasoline, and it can absorb water, which can cause oxidation, rust and corrosion. The claims of possible damage to vehicles from the use of ethanol blends above 10% have therefore attracted considerable negative publicity. Compared to diesel – the standard fuel in the heavy moving industry – ethanol is known to have a lower energy content so ethanol trucks require larger fuel tanks to achieve the same range as a diesel-powered vehicle. In Australia, a government review’ into the impacts of a 20% ethanol blend on vehicles found the information to be insufficient or conflicting but did identify a number of problems such as the possible perishing and swelling of elastomeric and plastic materials in fuel systems. Stakeholders in the motor vehicle industry have slated that warranties on motor vehicles and pump dispensing equipment could be at risk with the use of blends above 10% ethanol. Principle economist for the Australian Bureau of Agriculture Andrew Dickson points out that the money sugarcane growers get for their cane is not determined by the domestic consumption or domestic demand for ethanol, it is entirely determined by the world sugar market and the world trade in molasses He believes that the only way the sugar industry’ can benefit from the existence of an ethanol industry is if they invest in the ethanol industry. “The sugar producer does not get any more money for their molasses so what incentive do they have to produce any more?.” The cost of production also represents some challenges.

E. In Australia, fuel ethanol costs around 70 cents per litre compared with around 35 cents per litre for unleaded petrol. In America, one report revealed that even with government assistance, ethanol is dose to 35 per cent more than the price of diesel. Consequently, the production of ethanol requires government assistance to be competitive. A recent study by the Australian Bureau of Agricultural and Resource Economies found that without assistance, large-scale production of ethanol would not be commercially viable in Australia. Regardless of whether the Australian sugar industry will benefit from a mandated 10% ethanol mix, the expansion of ethanol production would certainly lead to increased economic activity in farming areas. It is inevitable that some expansion would be at the expense of existing industry. If ethanol becomes more popular, there will soon be more plants producing it. This means there will be a need for workers for the plants. The American National Ethanol Vehicle Coalition (NBVC) projects that employment will be boosted by 200,000 jobs and the balance of trade will be improved by over $2. The future of ethanol looks promising, for better or worse ethanol looks to be a serious contender for tomorrow’s fuel.