Pocket Science: Stealth mode in the sea

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The oceans are full of animals that seek safety in numbers, gathering together to confuse predators. But some opt for the opposite strategy.

Alexandrium is part of the sea’s collection of plankton. It’s a single-celled creature but it can create colonies by amassing together in long chains. At their most extreme, these colonies can form large swarms to produce harmful red tides.

As chains, Alexandrium swims and grows faster, but it is vulnerable to predators such as copepods – small relatives of crabs or shrimp. Erik Selander from theTechnical University of Denmark found that when the chains detect the chemical traces of copepods, they break apart. By turning back into single cells, they make themselves harder to find. They also swim at a slower pace to avoid creating telltale movements in the water. When threatened by predators, these plankton enter stealth mode.

Alexandrium isn’t the only ocean resident to use a split-and-survive strategy. The larva of the sand dollar avoids being spotted by splitting itself into two identical clones. Sand dollars are relatives of sea urchins. An adult is a flat, round disc but a larva (known as a pluteus) is a very different six-armed creature. A pluteus can swim but not very quickly, and certainly not fast enough to escape a hungry fish.

Dawn Vaughan and Richard Strathmann found that if a pluteus detects the smell of a fish, it clones itself in two. It grows a small bud that detaches and becomes a second genetically identical larva. The two clones are half the size of the original, each just an eighth of a millimetre across. Like Alexandrium, the sand dollar also has a stealth mode, and one that involves virgin birth!

Reference: Selander, Jakobsen, Lombard & Kiørboe. 2011. Grazer cues induce stealth behavior in marine dinoflagellates. PNAS http://dx.doi.org/10.1073/pnas.1011870108

Vaughn, D., Strathmann, R.R. (2008). Predators Induce Cloning in Echinoderm Larvae. Science, 319(5869), 1503-1503. DOI: 10.1126/science.1151995

Image by Tashiror

West Is Best?

By Timur Kuran

·

A new book by Ian Morris tracks the development of the East and the West over the millennia. But methodological problems lead him to miss the crucial differences between modern and premodern life -- and understate what is really keeping the West ahead.

TIMUR KURAN is Professor of Economics and Political Science and Gorter Family Professor of Islamic Studies at Duke University.

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In the 1940s, Joseph Needham, a British academic, began cataloging China's achievements in science and technology in an effort to understand why they were inferior to the West's. In his 40 years of study, he found that even though China may have seemed behind in such achievements at the moment, it had led the world in science a millennium before. He concluded that Confucianism and Taoism made a Chinese scientific revolution less likely because they allowed for only slow, incremental innovation, rather than overnight breakthroughs. Still, he recognized that this was only a partial explanation. Religions are not fixed, and if China's loss of scientific leadership stemmed from its religious attitudes, then what could account for the emergence and persistence of those attitudes?

Although Needham failed to resolve this great mystery, he made it impossible for other historians to continue to ignore questions about why some societies pull ahead and some fall behind. At a time when most Western, and even many non-Western, intellectuals believed in the intrinsic superiority of the West, Needham showed that both China's apparent shortcomings and the prevailing Western supremacy needed a historical explanation. His agenda became known as "the Needham question."

Broader analogues to the Needham question exist around the world. In the Middle Ages, the Middle East was at the forefront of optics, metallurgy, and mathematics. Its largest cities, libraries, and marketplaces dwarfed those in Europe. Subsequently, over the next half millennium, the Middle East slipped behind Europe in many realms, including science and medicine, finance and business, and literacy and living standards. But just as Confucianism and Taoism could not explain China's failures, Islam, often blamed for the Middle East's shortcomings, raises more questions than it answers. If Islam's supposedly retrograde system of beliefs explains the Middle East's recent failures, what accounts for its earlier successes?

ACCIDENTALLY SUPERIOR

Students of civilizational development have tended to approach disparities between the development of regions in two ways. The first, called "long-term lock-in," asserts that some essential advantage, such as a location with an abundance of natural resources, efficient governance, or values conducive to innovation, makes a civilization fundamentally and inevitably superior. For example, in explaining the rise of Europe, some scholars argue that the rise of Christianity under the political control of the Roman Empire prepared the West for modernization and ultimately the Industrial Revolution, which reinforced its superiority.

The second approach identifies some short-term accident as the cause of a temporary gap or reversal of fortune. When Christopher Columbus set sail for India and found a continent blocking the way, so goes a popular short-term accident theory, he initiated a string of events that accelerated the West's economic development and allowed the West to dominate the world. Another such theory holds that the Middle East was developmentally handicapped because of the devastation the Black Death wrought in the fourteenth century.

In Why the West Rules -- For Now, the classicist Ian Morris blends these two approaches. He finds that historical accidents affected the relative performance of the East and the West, sometimes for millennia. At the same time, he invariably sees geography as the principal determinant of performance trends. The taming of nature started in the West, he argues, because it had more plants and animals conducive to domestication. And Westerners initiated the global explorations that expanded the known world because it was easier for them to cross the Atlantic than for Easterners to cross the Pacific. Yet the advantages of geography have not made the West permanently superior. Every dominant civilization sooner or later reaches the limits of its capabilities, Morris argues. As its progress slows, other civilizations may catch up and leap ahead.

Morris gives the term "the West" an elastic and curiously broad meaning. The West, he writes, first included those societies that originated in the "Hilly Flanks," an arc-shaped area now split among Israel, Syria, Turkey, Iraq, and Iran, where the domestication of plants and animals began around 9500 BC; over time, it expanded to include the Mediterranean basin, Europe, the Americas, and Australia. "The East" initially consisted of societies that originated in the area between China's Yellow and Yangtze rivers, where the domestication process started around 7500 BC; later, it also came to include the countries between Japan and Indochina. For Morris, then, what is now called the Middle East has always been part of the West. Of course, the Middle East eventually fell behind, and much of it was colonized by Europe, making its trajectory more like that of the East. If the purpose of this book is to explore "why the West rules," surely this poses a major problem -- one that it neglects to confront.

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