Discover, January 1, 1998

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In the far northern reaches of the Siberian tundra is an enigmatic place called Popigai. The high cliffs along the rivers there are made of rock that shows signs of once having been completely melted, and satellite images reveal that the tundra actually forms a giant ring-shaped depression 60 miles across—which suggests that Popigai is a vast meteorite crater. Last July a team of Canadian and Russian scientists announced that they had determined when the meteorite hit: 35.7 million years ago, give or take 200,000 years. They calculated that date from the amount of radioactive argon that had decayed in the rocks since they resolidified after the impact.

Continue reading “The Year in Science: Earth 1997” →

Discover, January 1, 1998

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Treating wastewater is expensive: to get rid of organic matter, phosphates, and nitrogen compounds that farms and cities release into rivers, you need to pump the water through costly complexes of pumps, filters, and tanks. A tidal marsh, on the other hand, does the same job free of charge. The polluted water fertilizes plants and microbes, which in turn support a huge food web, and by the time the water makes its way out of the marsh, it’s scrubbed clean. One acre of tidal marsh performs about $2,800 worth of water purification every year. Multiply that by the 165 million acres of coastal wetlands on the planet, and you get a tidy annual bill of $462 billion.

Continue reading “The value of the free lunch” →

Discover, November 1, 1997

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Every scientific discipline has its defining challenges, the ones that mark the field’s outer limits. Astronomers feeling plucky might try to describe what it’s like to fall into a black hole. Particle physicists might attempt to see the guts of a quark. And biomechanists, who study how physical forces affect and direct the ways animals move, might reconstruct the biggest creatures ever to live on land: the sauropods, the long-necked, long-tailed, plant-eating behemoths of the age of dinosaurs. During their 160 million years on Earth, the sauropods produced species that grew over 130 feet long and that weighed in at 100 tons–animals that, biomechanically, defy comprehension.

Continue reading “Dinosaurs in Motion” →

Discover, November 1, 1997

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Walking through a forest is like sailing past an iceberg: you’re missing a big part of the picture. Trees hide nearly half their biomass in a vast tangle of roots, which in turn are usually woven into an even bigger web made of fungus. This benign fungal infection is a classic example of symbiosis, a relationship in which both organisms benefit. Trees can make new tissue from sunlight, water, and air, but their roots can’t extract enough vital nutrients such as nitrogen and phosphorus from the soil. Fungi produce digestive enzymes that free these compounds, but they can’t draw carbon from the air. So the organisms collaborate, the fungus taking carbon from the roots and pumping in soil nutrients in return.

Continue reading “The Web Below” →

Discover, September 1, 1997

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The puzzle–and joy–of evolutionary biology is to find the lost paths that life took to arrive at the strange forms it has today. Take, for example, the pufferfish. At first sight, it seems miserably adapted to the tropical waters where it makes its home: it is an unassuming, small fish, so slow you can easily catch it by hand. But when a predatory fish or bird attacks, a pufferfish goes through a unique transformation: it rapidly gulps water and swells into a huge, spiky, hard-shelled ball three times its normal size. How could anything like this evolve from an ordinary fish?

Continue reading “How the Pufferfish Got Its Puff” →