Discover, January 1, 1996

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Police detectives aren’t the only people who look for fingerprints. Climatologists do, too: they’ve been looking for the collective fingerprint of humanity on Earth’s climate. Most of them suspect that the 6 billion tons of carbon we pump into the atmosphere each year, in the form of carbon dioxide, could warm the planet through the greenhouse effect. In the coming century the warming could be dramatic; but is it detectable already? This past year two teams of climate modelers said yes: man-made global warming is happening–almost certainly, anyway, and it’s getting more certain every year.

Continue reading “Verdict (Almost) In” →

Discover, January 1, 1996

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Since 1983 Kaj Hoernle has been studying a couple of hot spots: the Canary and Madeira Islands, two volcanic chains located in the Atlantic southwest of Gibraltar. Like other hot spots–Hawaii, for instance–these islands are thought to have been formed by narrow, pipe-shaped plumes of hot rock rising from deep in Earth’s mantle. Hoernle, a geochemist at GEOMAR, a marine geology institute in Kiel, Germany, has been measuring the chemical fingerprints of rocks on the islands. Last March he reported some bizarre results: those supposedly distinctive fingerprints look much like the ones of rocks found far away–on Mount Etna in Sicily, for instance, and as far off as Germany.

Continue reading “Hot Sheet” →

Discover, January 1, 1996

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In evolution, fast small changes add up to slow big ones. A mutation happens in a blink of an eye. Then natural selection acts on the mutations in many individuals, and a species gradually adapts to its surroundings over thousands or millions of years. Magnificent transformations then take place, such as that of fish into land vertebrates 360 million years ago. Until recently, no one would have dared dream that we could ever follow a genetic trail such as the one from fin to hand. But an experiment this past year made that dream a reasonable one.

Continue reading “From Fin to Hand” →

Discover, December 31, 1995

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Underneath life’s variety, from mites to mastodons, there’s a profound sameness. Every cell of every organism, with the exception of a few viruses, encodes genetic information in DNA; DNA dispatches a single strand of RNA to make proteins; and the proteins do all the cellular grunt work. This system, so universal and uniform, poses a puzzle: where did it all come from? Complex as it is, it is hard to see how it could have sprung full-blown from the primordial soup. Might the first organisms instead have used some kind of “pre-NA”?

Continue reading “Life takes backbone” →

Discover, November 1, 1995

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Carel van Schaik had a dilemma. In August 1993 he was sitting in a crude shelter in the Suaq Balimbing swamp in Sumatra, deciding whether he should make the place his scientific home. Van Schaik, a primatologist at Duke University, studies orangutans. Suaq had a lot of them–as many as 20 individuals per square mile. But Suaq is a godforsaken place. Never mind the prevalence of malaria, dengue fever, and typhoid–simply following the orangutans as they moved high overhead in the trees required wading through thigh-high muck. Every day was an exercise in exhaustion.

Continue reading “Tooling Through the Trees” →