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Amber Time Machine

  • By George Poinar, Jr.
  • Posted 02.14.06
  • NOVA

I lifted to the window a nugget of golden Dominican amber entombing a small stingless bee. The sunlight infused it and illuminated the bee caught forever in flight—gossamer wings outstretched and perfectly preserved down to the last hair. Stark eyes appeared to be gazing at me. I contemplated this lustrous burial chamber and thought how wondrous it would be if we could see what this insect had beheld in its lifetime. Would the vistas of just one day be sufficient to reveal the wonders of life millions of years ago? What was that last fateful day like? And what events had taken place in the eras before this specimen arrived in my hand?

This stingless bee had already collected resin from the resin tree and secured it on its hind legs before it somehow got entombed, beginning an epochal journey. Enlarge Photo credit: Courtesy George Poinar, Jr.

A bee's life

One surmises that the bee was active in the dim light of early morning. She and her sisters gathered in the busy colony before beginning their various tasks. The young workers left for the nursery to attend the developing larvae. Older members flew out into the forest to collect pollen and nectar. The chore reserved for the aged bees was collecting the sticky resin utilized in nest construction from algarrobo trees. Our bee was among the resin gatherers. Off she skimmed with her companions, winding through the shadowy, towering amber forest, dodging the vines and lianas, avoiding tree trunks where hungry lizards lurked, and finally landing on the bark of an algarrobo near a large, yellow, viscous resin flow.

She scanned the surroundings, always on the lookout for hungry, sinister creatures that lurked in ambush—especially one well-adapted predator, the resin bug, a large, hairy-legged creature endowed with a huge beak that could easily penetrate the body and suck out the blood of an unwary bee. The resin bug's habit of coating the front legs and body parts with resin was repulsive, though effective in ensnaring prey. Only one swipe of the powerful front legs could pin the hapless victim long enough for the hypodermic-like beak to rip through the body wall.

Almost instantly, waves of thick fluid enveloped her.

The bee's compound eyes registered a kaleidoscopic image of the resin flow. Trapped within the vitelline pool lay other small arthropods, plant debris, and detritus. Not discerning any dreaded enemies, the bee began the painstaking job of removing small samples of resin with her mouth, coating them with saliva, and then attaching them to the hind legs in the form of little round balls. This exercise involved concentration and diligent work to prevent getting entrapped in the adhesive deposit. Finished at last, she was ready to return to the colony.

Like a creature out of a horror film, a long-legged resin bug looms over its intended victim, a stingless bee. In the end, both succumbed to the sticky resin. Enlarge Photo credit: Courtesy George Poinar, Jr.

Into a golden tomb

The attack came with lightning speed. Only a hazy brown blur was detected as the resin bug thrust its front legs toward her. Acting on impulse, she retreated from the lunging bug, but in her frantic attempt to avoid the predator she flew directly into the sticky trap. Almost instantly, waves of thick fluid enveloped her.

A few feeble attempts were all that could be mustered to extricate herself from that tenacious snare. In spite of valiant efforts, death came in seconds as viscous liquid seeped over the breathing pores, wrapping a mantle of gold around its victim. The sun shimmered on the silent insect cradled in the glistening tomb on the algarrobo trunk. As a gentle breeze wafted through the leaves, a fine layer of dust drifted over the surface of the elixir. Suspended in a motionless world, the entombed bee endured, the balls destined for the hive still attached to her outstretched legs.

Almost immediately, chemical changes began to take place. Sugars in the sap pulled the moisture from the insect's tissues while other chemicals infiltrated its cells. Bacteria carried in the gut initiated spore development in response to the adverse conditions. The next day, the xanthous domain of the bee was covered by a series of subsequent flows. Changes were also occurring in the resin itself as exposure to sunlight and oxygen caused the bonds between molecules to strengthen.

A petal from the algorrobo, an extinct species of leguminous tree that produced the resin which, over millions of years, transformed into Dominican amber Enlarge Photo credit: Courtesy George Poinar, Jr.

A long journey begins

Days grew into weeks and weeks into months. The tacky mass became harder but still clung to the bark of the tree. Finally, perhaps during a storm, the fossilized resin broke loose and came crashing down to the ground, lodging in a small crevice at the base of the tree. The material was now in the copal stage and no longer sticky. The chemical processes of polymerization and molecular cross-bonding would continue over the next few million years or so until the hardened resin, or copal, acquired the properties of amber.

Year after year, more debris, leaves, and twigs collected on top of the hardening copal. Wind, rain, and microorganisms degraded the accumulated plant litter but had no effect on our entombed bee. Eventually the mighty algarrobo crashed to the forest floor in a storm and added still another layer to the detritus covering the fossil.

For millennia all was tranquil. Ultimately a tempest fueled by a hurricane drove torrential rains across the bee's graveyard, washed away the accumulated organic matter, and exposed the fossil once again. Along with other fossilized pieces and plant debris, the specimen was washed by rivulets of floodwaters into raging streams, transported into a low-lying delta and shrouded with silt.

Another predator that lay in wait on algorrobo trunks for unsuspecting prey was the ant bug. Little did it expect that it would itself fall prey—to the engulfing resin. Enlarge Photo credit: Courtesy George Poinar, Jr.

A bee in the sea

The sea level began to change and salt water slowly inundated the area, submerging our entombed bee. Ocean waves dislodged the silt and exposed the amber. Around the fossil now lived an array of sea creatures. Crabs scampered over the resin graveyard, fish swam up and nudged amber nuggets, barnacles selected larger pieces for resting sites, and in heavy storms the fossilized resin was tumbled repeatedly by the currents. Among the waves dwelled a myriad of microscopic, shelled animals called foraminifera and coccoliths. When they died, their minute shells settled to the bottom and, together with bits of sediment, slowly covered the precious fossil on the seafloor. No longer would a diffuse light illuminate our bee, not for millions of years.

Suddenly, the sarcophagus was jarred as a hammer cracked open the rock in which it was inhumed.

Meanwhile, the mass of earth containing the amber alluvium drifted farther into the Carribbean Sea, having already moved from its original position between North and South America. The advance of this island mass was gradual, and those that once lived in that extinct silva were indifferent to the earthquakes that periodically shook the terrain.

A miner gazes into the inky depths of a Dominican amber mine, where the lighted candles of two fellow miners are the only things visible. Enlarge Photo credit: Courtesy George Poinar, Jr.

Brought to light

Eons passed and the sediment covering the amber now hardened into rock. Ultimately the strata containing the entombed creatures were subjected to still another natural force, that of mountain formation. Ponderously, those rocks that had been forged in the sea were elevated above the water. In some areas, the layers shifted and fractured, sometimes crazing the piece within. The bee was fortunate to be in a section of rock that was uplifted in its entirety. Towering skyward, the strata were folded into mountains. The upper boundaries, whose history could be told by the marine microorganisms in their matrices, were worn by the wind, washed by the rain, and eventually transformed into soil. Ultimately another forest became established, sending its roots down into the new loam that covered the bejeweled rocks, one quite dissimilar from the original forests.

One day, the silent graveyard, now lodged in a layer of marine rocks in the mountains of the northern Dominican Republic, was disturbed by some minor shock waves. These jolts continued for several days, eventually becoming more intense. The sediment containing the amber had been discovered and was being laboriously removed. Suddenly, the sarcophagus was jarred as a hammer cracked open the rock in which it was inhumed. Together with other pieces that had been dislodged from the rock, the bee and its tomb toppled to the floor of the mine. In the flickering candlelight, she was picked up and placed into a bag. Later, the day's take was sorted on a rickety wooden table where dark eyes scrutinized each piece intently, selecting those with fossils to be polished and sold and thereby continuing the process that brought this bee to my collection.

This feature originally appeared on the site for the NOVA program Jewel of the Earth.

George Poinar, Jr. George Poinar, Jr., is a research fellow at Oregon State University. Together with his wife Roberta, he has coauthored several books on amber, including The Amber Forest: A Reconstruction of a Vanished World (Princeton University Press, 1999), from which this article was excerpted with kind permission of the author and publisher.

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