lunes, 11 de junio de 2012

Jewel Of The Earth (NOVA Documentary)

ORIGINAL: Nova

Broadcast (2007) Forty million years ago a diverse community of insects living at the bottom of a tree in a temperate forest chanced into a sticky pool of pine resin. Then a mere 67 years ago a young boy named David Attenborough was given the amber stone containing the entombed bugs. "Jewel of the Earth" explores the remarkable time capsule of ancient life preserved in this and countless other samples of fossilized tree resin, or amber.

Sir David Attenborough, now grown up and a celebrated naturalist and TV personality, hosts the program. As he makes abundantly clear in the show, he is still entranced with the amber specimen from his youth and the seemingly magical quality of the material to serve as a crystal-clear window to an age before humans walked the Earth. Coincidentally, David's brother Richard starred in the movie that made amber famous: Jurassic Park, in which Richard plays a billionaire entrepreneur who extracts DNA from amber-entombed mosquitoes in order to clone living replicas of their prey—dinosaurs. While such a scenario is probably unlikely, amber can resurrect prehistoric life in a quite different way, as NOVA demonstrates by probing the amber-encased clues that paint a fascinating picture of ancient biomes.


For example, most of the world's amber comes from the Baltic region of northern Europe, where, on the ample evidence of insects, plant fragments, and other trapped material, a vast temperate forest flourished about 40 million years ago. Sir Attenborough's boyhood keepsake is a piece of Baltic amber, which he investigates through a microscope with the help of biologist Elzbieta Sontag of the University of Gdansk, finding a long-legged fly, a fungus gnat, an aphid, an ant, and a mite—all denizens of the lower forest floor. By contrast, much of the amber found in the Dominican Republic—the second most significant source studied so far—is about 20 million years old and hails from an ancient rain forest. George and Roberta Poinar of Oregon State University have reconstructed this vanished ecosystem in spectacular detail, based on such clues as a tadpole that probably resided in a water-filled tropical bromeliad before being upended, along with a marsh beetle, into a patch of tree resin that eventually turned into amber.

An even more ancient Dominican sample, from 150 million years ago, contains a honeypot ant. Since this ant is now found only in Australia, the specimen is evidence for a conjectured super-continent that once comprised most of Earth's landmasses. High-tech medical scanners have shed light on many other amber inclusions, diagnosing a broken back on a gecko, for instance, which suggests the lizard was a bird's prey before being accidentally dropped into resin. The most controversial research on amber, however, is the effort to extract DNA from trapped creatures, just like in Jurassic Park. So far, two teams, including the Poinars, have announced success. However, follow-up studies indicate the DNA found by both groups was a contaminant, not the real, ancient stuff. Setbacks aside, scientists have only just begun to reveal the secrets to be discovered in the warm, glowing, glassy world of amber.

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