AMBER

Because amber oxidizes and degrades when exposed to oxygen, it is preserved only under special conditions. Thus it is almost always found in dense, wet sediments, such as clay and sand that formed at the bottom of an ancient lagoon or a river delta. While hundreds of amber deposits occur around the world, most of them contain only trace amounts of the substance; only about twenty deposits in the world contain amounts of amber large enough to be mined.

Amber has preserved ancient life to such infinitesimal detail that it even captures fragments of DNA of the organisms entrapped in it. Such a wide variety of creatures has been found in Dominican amber, for example, that scientists are able to reconstruct this ancient ecosystem with amazing intricacy.  Everything in this reconstruction derives from direct evidence provided by the amber fossils or is inferred on the basis of plant-feeding forms of insects, such as fig wasps, which specifically pollinate fig trees.

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TIME Magazine

February 12, 1996 Volume 147, No. 7

SCIENCE/FOSSILS

FOREVER AMBER

Art, Science And Historic Lore Intersect Exquisitely In Gems Of Ancient Resin

MICHAEL D. LEMONICK  

The Etruscans prized it as highly as gold. The Greeks mythologized it as the tears of Apollo's daughters, solidified when they cried for their dead brother Phaeton. The Romans considered a single piece worth more than a slave. Cultures stretching from Central America to the Far East, from the Mediterranean to Scandinavia, have used it both as a powerful medicine and as a medium for exquisite jewelry and works of fine art.

Scientists, too, value amber. Trapped within the translucent, usually gold-colored substance are some of the most ancient examples of certain species known to science. The oldest ants, moths, stingless bees, caterpillars, termites, mushrooms and pollen grains, some of them dating back tens of millions of years, have been found in amber. And unlike ordinary fossils, which are relatively crude rock molds of prehistoric life forms, these specimens are often perfectly preserved, with the most delicate feat ures intact.

Now entomologist David Grimaldi of New York City's American Museum of Natural History has announced a find he calls "scientifically the most important of all amber fossils." It's three tiny flowers, probably from an oak tree, that date to the age of the dinosaurs, some 90 million years ago. That makes them the oldest intact flowers ever found in amber, and an important clue to the origin of the flowering plants that now dominate the earth.

Amber's dual roles as artistic medium and scientific research tool have rarely intersected. But that's just what they'll do starting later this week. On Saturday the American Museum will unveil, under Grimaldi's curatorial supervision, the most compreh ensive display of amber ever mounted. The exhibition, "Amber: Window to the Past," features 146 fossil specimens and 94 decorative objects from museums and private collections all over the world, including Stone Age amulets from Scandinavia, 18t h and 19th century Chinese figurines and treasures once owned by the Medicis of Italy and the Czars of Russia. Many of these artworks have never been publicly shown; none of them have ever been seen in North America. A lavishly illustrated companion text is being published by Abrams ($49.50).

Not bad for a substance that's essentially dried-up tree resin. The viscous stuff that eventually turns into amber comes from a variety of ancient trees, mostly conifers, including pines and extinct relatives of sequoias and cedars, but also some decid uous trees. It probably evolved, says Grimaldi, as a defense against wood-boring insects. "As it dripped down the bark," he explains, "it acted like flypaper and encapsulated them, hermetically sealing the trees' wounds at the same time.'

Eventually the trees and their stalactites of dried resin fell, some of them ending up buried in soft sediments at the bottom of still and shallow bodies of water. There, over millions of years, the molecules of resin gradually amalgamated into long, d urable chains, creating a material remarkably like plastic: airtight, watertight, chemically inert.

Although wood-boring insects might have been its target, the resin would also trap anything else that happened to stumble into it, including small lizards and frogs. Bad luck for them, but extraordinary good fortune for evolutionary biologists. In one major deposit--a site in New Jersey whose location is closely guarded--Grimaldi and a team of volunteers have found nearly 100 previously unknown ancient species of plants and animals. These and other discoveries around the world have given scientists som e important insights into the workings of natural selection--how, for example, insects and flowers helped guide each other's evolution.  

Other samples provide dramatic snapshots of prehistoric behavior: mites hitchhiking on the back of sweat bees; a leaf beetle spitting out a stream of noxious bubbles in self-defense; spiders caught in the act of mating; a praying mantis attacked by ant s; a spider finishing off a millipede.

As anybody who has seen Jurassic Park knows, plants and animals sealed in amber are a potential source of prehistoric DNA. Scientists have extracted genetic material from, among other things, a 17 million-year-old magnolia leaf, a 30 million-year-old t ermite and a 120 million-year-old weevil. Yet no serious biologist believes it will ever be possible to clone a dinosaur from a few bits of DNA. Even so excellent a preservative as amber apparently can't keep DNA from breaking down into fragments that may be scientifically interesting but are biologically inert. That's one reason many researchers doubt the claims of California scientists who announced last year that they had managed to revive bacteria preserved in amber for 25 million years.

For scientists, a piece of amber with nothing trapped inside is not so exciting. For artists and their patrons, however, it is an uncut gem. According to Grimaldi, Stone Age artisans used amber found on beaches of the Baltic Sea 10,000 years ago to car ve amulets, pendants and tiny figurines. Indeed, Baltic deposits were Western civilization's primary source of amber at least as far back as 1200 B.C.

The name notwithstanding, amber isn't always amber in color. It can also be milky white, red and even blue or green--more than 250 different shades in all, say researchers--and artists have used just about every one of them.