Reading — 2026 Jan–Apr Recall Set 8

Images of deserts in the United States show dusty, barren landscapes, but the land may not always have been this way. Ever since settlers moved west across the US, there has been dust, clouds of it, everywhere. It was part of the landscape, or so it seemed to them. But there were no records of the landscape of the West until the settlers arrived. Now, evidence is starting to emerge which suggests that before the settlers, there was very little dust. The evidence comes from the San Juan Mountains of southwest Colorado, downwind of Arizona and New Mexico. There, Jason Neff, a geochemist from the University of Colorado, has been analyzing sediments, the sand, stones and mud, laid down over the past 5,000 years. Atmospheric dust was minimal throughout those five millennia until the mid-19th century, he says, but then, ‘from about 1860 to 1900, dust deposition rates shot up.’ This is surprising because usually dry means dusty, and the American West has almost always been dry, often drier than today. There was a near-permanent drought between 900 and 1300 which was so intense that it destroyed a series of Native American civilizations, including the Anasazi, whose cliff homes are now US national treasures. Yet the evidence from the San Juan lakes is that it was not dusty. Even as their civilization was collapsing, the Anasazi seem to have protected their soils from erosion. This was not the case with the European settlers once they brought their cows. The landscape the cattle were introduced to was remarkably ill-equipped to cope with grazing animals, says Neff. ‘Unlike most other parts of the US, there were few grazers in the American Southwest until the Europeans came. No bison and few antelope or deer.’ In the Great Plains to the east and north, bison roamed in vast herds. Their regular grazing had created tough grass, while the herds manured the soil. In the Southwest, the land had few defenses against a sudden invasion of millions of livestock, whose teeth stripped the grass and whose hooves punctured the hard crust of desert soils that protected them from the wind. The invasion was sudden, funded by a bubble of speculative investment, much of it from Britain. The money went into railroads and herds of cattle and sheep that rode the rails to the wide open pastures. By 1900, when sedimentation rates peaked, there were 20 million cattle and 25 million sheep in the West. One of the biggest ranches was owned by the Aztec Land and Cattle Company, which owned a million acres of land by 1884. Each acre had cost the company a mere 50 cents, and like many other speculators, it was only interested in quick profits and had little incentive to protect the soils from overgrazing. By the time Aztec sold the ranch in 1901, it was barren, with cattle carcasses scattered across the exhausted land. Such was the damage to the grasslands that even now few of the pastures have recovered. The parched and exposed soil simply blew away. The 1862 Homestead Act was passed in order to encourage the populating of the West. Any family willing to make the journey was entitled to claim 160 acres and farm it. Yet by the time people moved west in large numbers, the cattle companies had taken most of the land and surrounded it with barbed wire. The water sources were therefore cut off, and were aggressively guarded. It was only in the 1930s, with the passage of the Taylor Grazing Act, that federal authorities finally sought to limit cattle herds. Soil scientists have known for a while about the importance of the hard crust that forms on arid soils. ‘These crusts can survive winds of up to a hundred miles an hour, but cattle hooves break the crust,’ says Jayne Belnap, a soil ecologist at the US Geological Survey, Utah. The scale of the dust clouds created by the livestock invasion has until now been largely unknown. When Neff first discovered dust in Colorado lake sediments laid down in the 19th century, he was initially unsure where it came from. Maybe it had crossed the Pacific from China’s Gobi Desert. But after investigating the size and chemical composition of the dust, Neff was clear that it mostly came from the American Southwest, mainly Arizona and New Mexico. Now, with the soil crusts gone, dust clouds still head north and are having significant ecological effects in the Colorado mountains. They carry nutrients with them into areas which previously evolved and survived without them. But perhaps the most dramatic impact of the dust has been on snowfields in the Rocky Mountain Range. Even a thin sprinkling of dark material means snow absorbs more solar radiation, meaning that snowmelt occurs far more rapidly during springtime. The impact on the ski tourism industry is obvious. The loss of snow and the shrinking of glaciers across the American West in the past century have been dramatic. Glacier National Park in Montana, for example, has lost three-quarters of its snow cover since 1910. All this is frequently attributed to global warming. While this almost certainly plays a role, Neff’s findings suggest that dust may also contribute.

The call for people to eat less meat to save the planet is growing louder, so if less is good, wouldn’t none be better? To find out, let’s imagine what would happen if the world eliminated meat, milk and eggs from its diet, then trace the effects. Last year the world consumed 289 million tonnes of meat, 700 million tonnes of milk and 1.2 billion eggs. Environmentally speaking, this came at an enormous cost. All agriculture damages the environment. Take for example the felled forests and the common use of irrigation systems. And it may surprise you to know that agriculture creates more greenhouse gases than all methods of transport put together. Livestock farming does the most damage. In part, that is because most livestock eat grain that could be used to feed human populations, and farmers are forced to grow more than we would otherwise need to meet the demand. Altogether, if we switched to a vegan diet, meaning no meat, dairy or eggs, the land currently required for crops would drop by an estimated 21 per cent, about 3.4 million hectares, roughly the size of India. One environmental impact that would also lessen through a reduction in animal farming would be that of the nitrogen emitted from agricultural processes, which spreads into both waterways and land. According to environmental scientist Allison Leach, if everyone eliminated dairy products and eggs, this kind of pollution would fall by 60%. Livestock production has another serious environmental impact. Global statistics are hard to come by, but in the US at least, livestock account for 55% of erosion, mostly from forests being cut down to make way for grazing land. On top of this, half of all antibiotics manufactured are fed to livestock as part of their normal diet, a practice that is leading to drug-resistant bacteria. A meat-free world, then would be greener in many ways. However, if everyone opted to give up meat there would be significant costs too. For most of human history, livestock grazed on land that wasn’t suitable for ploughing, and in doing so they converted inedible grass into edible meat and milk. Even today, a flock of sheep or goats can be the most efficient way to get food from marginal land. In a world in which over a billion people do not have enough to eat, using this land for crop production would contribute to food insecurity. In some parts of the world today, livestock like chickens, for instance, can subsist on leftovers and whatever they find. Tara Garnett, who heads the Food Climate Research Network at the University of Surrey, points out the usefulness of these animals. By giving them your leftovers, she says, they deal with your rubbish, and you get meat. Garnett admits, though, that if this kind of approach were generally adopted, it would require a major adjustment in food preferences; people would have to get used to chicken, for example, with less fat. Another downside to a meat-free world would be the disappearance of animal by-products. Such a world would have to replace the 11 million tonnes of leather and 2 million tonnes of wool that come annually from livestock farming and which are turned into clothing. Furthermore, even ardent vegetarians acknowledge that dairy products and meat may be a good thing in poorer countries. ‘Whilst there’s no doubt that considerable reduction of meat consumption would have an environmental benefit, we do have to be careful about saying it would be the best solution if the whole world went vegetarian,’ says Annette Pinner, chief executive of the UK Vegetarian Society. For many of the world’s poorest rural residents, an animal may represent their only realistic hope for a little extra income, and a little animal protein can make a big difference to a marginal diet. What if we decided on a no-meat vegetarian diet, rather than a vegan diet? After all, milk and eggs are very efficient ways of producing animal calories. ‘It’s difficult to switch to a no-meat-but-milk diet,’ says Helmut Haberl, a social ecologist. ‘Dairy cows must calve every year to keep producing milk, and only half their offspring will be female. While many vegetarians see moral reasons not to kill and eat the males, there is surely no practical reason to waste so much meat.’ Similar arguments apply to chickens kept for eggs. So even though a meat-free world sounds good on paper, it is likely that a utopian future will still have some animal products in it. The real questions, then, are how much meat do we want, and how will we produce it? The answers depend on how you approach these questions. The most straightforward approach is to assume that the world will continue to want evermore meat. The United Nations’ best guess is that by 2050, the world will need to more than double its production of meat, an increase that would be environmentally disastrous. Under this scenario the goal will have to be producing the most meat at the lowest environmental cost. According to Walter Falcon, an agricultural economist, this means fewer free range cattle and sheep in green fields. ‘If you’re going to keep some livestock systems, I think the ones you’ll want to keep are the intensive ones,’ he says. Of course this does not take into account animal welfare issues, as intensive farming usually means poor living conditions and the use of growth hormones.

As Daniel Haworth is settled into a high chair and wheeled behind a black screen, a sudden look of worry furrows his 9-month-old brow. His dark blue eyes dart left and right in search of the familiar reassurance of his mother’s face. She calls his name and makes soothing noises, but Daniel senses something unusual is happening. He sucks his fingers for comfort, but, finding no solace, his mouth crumples, his body stiffens, and he lets rip an almighty shriek of distress. Mom picks him up, reassures him, and two minutes later, a chortling and alert Daniel returns to the darkened booth behind the screen and submits himself to Baby lab, a unit set up in 2005 at the University of Manchester in northwest England to investigate how babies think. Watching infants piece life together, seeing their senses, emotions and motor skills take shape, is a source of mystery and endless fascination—at least to parents and developmental psychologists. We can decode their signals of distress or read a million messages into their first smile. But how much do we really know about what’s going on behind those wide, innocent eyes? How much of their understanding of and response to the world comes preloaded at birth? How much is built from scratch by experience? Such are the questions being explored at Babylab. Though the facility is just 18 months old and has tested only 100 infants, it’s already challenging current thinking on what babies know and how they come to know it. Daniel is now engrossed in watching video clips of a red toy train on a circular track. The train disappears into a tunnel and emerges on the other side. A hidden device above the screen is tracing Daniel’s eyes as they follow the train and measuring the diameter of his pupils 50 times a second. As the child gets bored—or “habituated”, as psychologists call the process—his attention level steadily drops. But it picks up a little whenever some novelty is introduced. The train might be green, or it might be blue. And sometimes an impossible thing happens—the train goes into the tunnel one color and comes out another. Variations of experiments like this one, examining infant attention, have been a standard tool of developmental psychology ever since the Swiss pioneer of the field, Jean Piaget, started experimenting on his children in the 1920s. Piaget’s work led him to conclude that infants younger than 9 months have no innate knowledge of how the world works or any sense of “object permanence” (that people and things still exist even when they’re not seen). Instead, babies must gradually construct this knowledge from experience. Piaget’s “constructivist” theories were massively influential on postwar educators and psychologists, but over the past 20 years or so they have been largely set aside by a new generation of “nativist” psychologists and cognitive scientists whose more sophisticated experiments led them to theorize that infants arrive already equipped with some knowledge of the physical world and even rudimentary programming for math and language. Babylab director Sylvain Sirois has been putting these smart-baby theories through a rigorous set of tests. His conclusions so far tend to be more Piagetian: “Babies,” he says, “know squat.” What Sirois and his postgraduate assistant Iain Jackson are challenging is the interpretation of a variety of classic experiments begun in the mid-1980s in which babies were shown physical events that appeared to violate such basic concepts as gravity, solidity and contiguity. In one such experiment, by University of Illinois psychologist Renée Baillargeon, a hinged wooden panel appeared to pass right through a box. Baillargeon and M.I.T’s Elizabeth Spelke found that babies as young as 3½ months would reliably look longer at the impossible event than at the normal one. Their conclusion: babies have enough built-in knowledge to recognize that something is wrong. Sirois does not take issue with the way these experiments were conducted. “The methods are correct and replicable,” he says. “It’s the interpretation that’s the problem.” In a critical review to be published in the forthcoming issue of the European Journal of Developmental Psychology, he and Jackson pour cold water over recent experiments that claim to have observed innate or precocious social cognition skills in infants. His own experiments indicate that a baby’s fascination with physically impossible events merely reflects a response to stimuli that are novel. Data from the eye tracker and the measurement of the pupils (which widen in response to arousal or interest) show that impossible events involving familiar objects are no more interesting than possible events involving novel objects. In other words, when Daniel has seen the red train come out of the tunnel green a few times, he gets as bored as when it stays the same color. The mistake of previous research, says Sirois, has been to leap to the conclusion that infants can understand the concept of an impossibility from the mere fact that they are able to perceive some novelty in it. “The real explanation is boring,” he says. So how do babies bridge the gap between knowing squat and drawing triangles—a task Daniel’s sister Lois, 2½, is happily tackling as she waits for her brother? “Babies have to learn everything, but as Piaget was saying, they start with a few primitive reflexes that get things going,” says Sirois. For example, hardwired in the brain is an instinct that draws a baby’s eyes to a human face. From brain imaging studies we also know that the brain has some sort of visual buffer that continues to represent objects after they have been removed—a lingering perception rather than conceptual understanding. So when babies encounter novel or unexpected events, Sirois explains, “there’s a mismatch between the buffer and the information they’re getting at that moment. And what you do when you’ve got a mismatch is you try to clear the buffer. And that takes attention.” So learning, says Sirois, is essentially the laborious business of resolving mismatches. “The thing is, you can do a lot of it with this wet, sticky thing called a brain. It’s a fantastic, statistical-learning machine.” Daniel, exams ended, picks up a plastic tiger and, chewing thoughtfully upon its head, smiles as if to agree.