Tiger Shark Meals
Tiger sharks, the fourth-largest type of shark on the planet, are known to consume not only fish, turtles, and mammals such as seals but also an extremely wide variety of other sea creatures. Even man-made objects that end up in the sea, such as rubber tires and car license plates, are routinely on the menu for these large predators. ( 26 ), they seem to deserve their nickname, the “garbage cans of the sea.”
Ecologist Marcus Drymon of Mississippi State University recently discovered that the diet of tiger sharks ( 27 ). The animals are known to make meals of seabirds, such as gulls or pelicans, so when a tiger shark that Drymon caught during a routine tracking program happened to vomit some feathers onto his boat, he was not particularly shocked. However, analysis revealed the feathers belonged to a so-called backyard bird. These are birds that live on land and are often seen in people’s gardens, such as sparrows and wrens. Analysis of the stomach contents of more tiger sharks confirmed that backyard birds were in fact regularly meeting this fate.
The cause of this phenomenon likely lies in the backyard birds’ habit of migrating. Migrating birds are often knocked into the sea by storms. Unaccustomed to the water, they are usually unable to return to the air once their feathers become soaked. This explains how the sharks ( 28 ). Drymon suspects tiger sharks purposely give birth in areas that migrating birds fly over. The fallen animals provide an easy meal for the baby sharks, who are not yet able to hunt prey that is more difficult to catch.
Home Advantage
Home advantage is a well-documented phenomenon in certain sports, such as baseball and soccer, where teams are statistically more likely to win when playing at home than when playing away games. One proposed explanation for this is the ( 29 ). However, author David Runciman notes that if this were true, there would have been a much bigger reduction in home advantage over the past century than there has been, since luxuries such as firstclass flights, fancy hotels, and accompaniment by therapists for athletes playing away from home have become standard.
Another potential factor is players’ familiarity with their home field. Although sports fields do not differ significantly from one place to another, Runciman points out that being familiar with even minor aspects of one’s surroundings can “enhance confidence in the performance of repetitive physical tasks.” ( 30 ) when a team moves to a new home field. The team’s home advantage initially goes away, only to return once the athletes get used to their new surroundings.
The way sports venues are constructed also seems to affect home advantage. In an analysis of over 35,000 Major League baseball games, researchers Richard Zeller and Tim Jurkovac reported that teams playing in a domed stadium at home won 10.5 percent more games than when they were on the road. On the other hand, teams playing in an open-air stadium won 7.2 percent more games at home. The researchers noted that domed stadiums trap noise within the stadium and that the enthusiasm from fans in the crowd helps teams play better and win more games. ( 31 ), teams whose home stadiums are domed perform especially well at home.
Cassina
With its rich, dark color, caffeinated kick, and roasted aroma, cassina, a beverage made from the leaves of a type of holly tree, could easily be mistaken for black tea. Cassina, however, does not come from China, where tea originated, but from the southern coastal areas of North America. Native Americans began drying and roasting cassina leaves over a thousand years ago, and trade in the “black drink,” as cassina was known, stretched across the continent before the arrival of European colonizers. The colonizers, too, adopted the beverage, drinking cassina daily in Florida and other southern colonies.
The potential for competition worried European importers of black tea, however, and they set out to use any means necessary to prevent this. Early European observers had reported seeing Native Americans drinking cassina during rituals that involved “purging” the consumption of substances that cause vomiting. Historians think the substance consumed in the rituals was likely cassina mixed with other herbs, or perhaps not cassina at all, as cassina on its own does not make people throw up when consumed in typical quantities. Still, when first classifying the plant, scientists gave it the Latin name Ilex vomitoria, or “holly that causes vomiting.” Some historians suspect tea companies encouraged scientists perhaps by means of a bribe to make the beverage sound particularly unappealing.
As a result, in the 1700s, when cassina was marketed in Europe as an alternative to expensive black tea, tea importers quickly spread word of how the plant supposedly caused vomiting. The campaign was successful, as cassina failed to gain popularity and was largely forgotten. In recent years, however, chefs and consumers in the southern United States have rediscovered it as part of the growing movement to consume sustainable items obtained from local sources. An added attraction is that the plant is strong and resistant to drought. Advocates are hoping cassina can overcome its unfortunate scientific name and history to emerge as a popular alternative to tea and coffee.
The Hebridean Ark Tree Project
On the Outer Hebrides, a group of islands near the Scottish mainland, an ambitious tree-planting project has started. Called the Hebridean Ark Tree Project, it aims to return the islands to their ancient state of thick forest cover. Getting trees to grow on the islands is a challenge, however. The climate is harsh, with low average temperatures and strong winds that spray the land with saltwater, which harms trees if it is absorbed through their roots. In addition, much of the ground consists of peat, a nutrient-poor mixture of organic materials. Peat forms when low temperatures, water, and a lack of oxygen result in organic matter, such as dead plants, failing to decay completely. Furthermore, animals, such as deer and sheep, will almost certainly feed on young trees. To deal with the peat problem, instead of growing trees on top of the peat, the project will grow them on the edges. Keeping animals away is less straightforward, however, as fencing may be impractical, and reducing their numbers would cause controversy.
Despite the various challenges, those involved in the project believe it can succeed. Evidence shows that forests on the islands grew well thousands of years ago. Although the climate has cooled since then, it was primarily human activity that led to the current situation. Firstly, Viking invaders who arrived from nearby Scandinavia around AD 800 cut down trees to make sure the native people could not use wood for boat building. After settling on the islands, the invaders cleared even more trees for raising animals and growing crops. After a battle on the island of Lewis in 1098, the Vikings introduced a slash-and-burn policy that severely damaged local tree populations. Once the forests on the Outer Hebrides were gone, peat growth began to take over.
A major issue facing the project is selecting which trees to plant. The focus is on native trees, such as aspen and birch, but the origin of the seeds is critical. Project supporter David Mackay recalls a previous reforestation plan on the Shetland Islands, where environmental conditions resemble those on the Outer Hebrides. That plan initially used young trees brought over from the Scottish mainland, but eventually, seeds and trees from the nearby Faroe Islands had to be introduced. Mackay notes that the genetic makeup of trees from the mainland does not enable them to deal with harsh island conditions. For the Hebridean Ark Tree Project, seeds are being taken from trees that currently remain on the Outer Hebrides and grown into some 100,000 young tree saplings before being transferred back to the islands.
A Closer Look at Vitamin Supplements
In 1970, American chemist Linus Pauling published the book Vitamin C and the Common Cold , which promoted the idea of taking vitamin supplements to prevent and treat disease. Pauling believed high doses of vitamin C could cure the common cold. Though scientific evidence to support his claim was entirely lacking, people believed it owing to the fact that he was widely respected as a scientist. Pauling had published over a thousand scientific papers and books about chemical bonds, molecular biology, and the structure of proteins, and in 1954 he had been awarded the Nobel Prize in Chemistry. Not surprisingly, then, when he claimed that vitamin C could prevent and treat colds, people listened, and vitamin C sales soared. Over time, his claim grew to include other vitamins and supplements, and he even stated that large doses could cure everything from the flu to cancer and HIV.
Research had already found evidence linking diets high in fruits and vegetables with greater longevity and lower rates of cancer, heart failure, and other age-related diseases. It was also known that fruits and vegetables are high in substances such as beta carotene, folic acid, and vitamins A, C, and E, which are called antioxidants. Antioxidants prevent and repair cell damage caused by free radicals, which are formed naturally by the body as part of its normal function but also come from external sources, such as environmental pollution. When there are more free radicals than antioxidants in the body, an imbalance called oxidative stress occurs, which can lead to cancer and other diseases. Pauling had the idea that, since antioxidants can lessen the damage caused by free radicals, increasing antioxidant levels with supplements could prevent illness.
However, in the years since Pauling’s claim about vitamin C was published, numerous studies have shown that vitamin C cannot cure the common cold. In fact, most studies evaluating similar supplements have not supported their use. Notably, studies showed that long-term smokers who took beta carotene and vitamin A or E supplements actually had an increased likelihood of developing lung cancer or heart disease compared with those who did not. Vitamin E was found to increase the risk of heart failure, and men who took multivitamins were more likely to develop prostate cancer. This contradiction has been called the “antioxidant paradox.”
What could the reason for this paradox be? Although taking high doses of vitamins can increase antioxidant levels, it must also be remembered that a low or moderate level of free radicals serves a beneficial purpose in defending the body from illness. When the body releases free radicals as part of its immune response, they target and destroy bacteria, viruses, and damaged cells including cancerous and precancerous ones. Taking large doses of antioxidants may interrupt this natural defensive action and allow disease to grow stronger. This does not mean, however, that supplements are entirely without value. Vitamin supplements, for example, are effective in treating diseases associated with malnutrition, such as scurvy, which results from people not getting enough vitamin C. However, our usage of supplements to address illnesses caused by bacteria and viruses clearly needs a closer look.
