As if terrorism, warfare, and diseases weren't scary enough, the past year has offered some ominous signs of an impending shark invasion into the waters where we swim, surf, and play, as the number of sightings and unprovoked strikes on humans has ticked ever upward. The number of reported shark attacks worldwide increased 25 percent in 2010, to a total of 79, and warm-weather shark observations off the U.S. East Coast is rising, prompting beach closures last summer everywhere from Brooklyn to Cape Cod. In January of this year, a pilot flying off Palm Beach, Florida, saw literally thousands of sharks, capturing the swarm with his iPhone (and terrifying plenty of humans in the process). A month later, police reported that two great whites had killed a diver off the South Australian coast. And in June, a Cornish mackerel fisherman claimed that a 6-foot oceanic whitetip shark rammed his boat, setting off a British media frenzy. These developments seem to suggest that sharks pose a more serious threat to us now than they did before -- as if they're either expanding in numbers, or just more determined to get us.
A look at the complex relationship between humans and sharks, in pictures.
Headlines such as "Fisherman's boat rammed by man-eating shark off coastline" and "Mom runs for son killed in shark attack," after all, would strike terror into the hearts of even the most confident oceangoers.
In fact, the truth is more complicated. Sharks aren't coming after us; we're coming to them. Humans and sharks have been able to share the Earth for millions of years without a whole lot of interaction. But the two species are coming into contact more frequently than ever because of a variety of factors, including demographics (more people can afford beach vacations and growing urbanization means more people are living closer to the ocean), as well as environmental ones (such as climate change). That's bad news for sharks, whose populations -- despite the increased sightings -- are in decline. And it has also provoked an international policy fight that pits global heavyweights like the United States and Europe against Japan and China, with small island nations divided between the two sides.
At first glance, sharks -- with their sharp jaws, torpedo-shaped bodies, and unusual sensing abilities -- appear to be bizarre vestiges of a distant past. But they can also tell us a lot about our present and our future. Where sharks appear in big numbers, coral reefs and other marine life around them thrive because they remove weak and sick animals from the system and can keep midlevel predators in check. When they shift their migrations, scientists often detect a shift in ocean temperatures and prey populations. For researchers seeking to create a more efficient electric battery, faster vessels, or a robot that can track oil and chemical spills underwater, sharks' sleek and extraordinarily efficient bodies offer inspiration for design. In countries where their fins end up at the dinner table, economists can generally find rising incomes. The animal humans fear most has become a global commodity, an economic indicator, and environmental harbinger of things to come.
Most importantly, humans' interaction with sharks shows the extent to which we are plumbing the ocean's depths. After all, they don't venture onto our territory; we encroach on theirs. In contrast to several Pacific island societies, which developed faith traditions around sharks eons ago after encountering them at sea, Westerners arrived late in the game when it comes to dealing with these creatures. Sharks only began to permeate the public consciousness in Europe in the late 1500s, when seafaring began in earnest. The first detailed eyewitness account of a shark strike comes from the 1580 Fugger News-Letter, which chronicles a sailor falling off his ship somewhere between Portugal and India. He caught a line that his shipmates tossed him, but according to the article, "there appeared from below the surface of the sea a large monster, called Tiburon; it rushed on the man and tore him to pieces before our very eyes. That surely was a grievous death."