Portions of this article is from the University of Arizona Communications.
The world's longest-living trees reside right here in the western United States. These are the Pinus longaeva, commonly known as the Bristlecone pine. They grow high in the mountains of Nevada and California.
Some of the pines living right now were growing when the pyramids in Egypt were built many centuries ago. Rex Adams, a senior research specialist at the University of Arizona's Laboratory of Tree-Ring Research describes how tough these trees are to kill.
"There is an argument that unless there's an extremely stressful period of time or they're struck by lightning or killed by fire, there's not a physiological reason for these trees to die," said Adams.
The University of Arizona is home to one of the leading Tree-Ring research departments in the world. The Laboratory of Tree-Ring Research has parts of the oldest Bristlecone pine known to have lived. The way those pieces came into existence at UA is part of a tragic story.
In the 1960s a graduate student from the University of North Carolina traveled to Nevada to research the age of these ancient trees. The student's studies meant he needed to count tree rings to determine the age of the pines. This can be done by taking core samples.
Core samples are taken by using a tool that bores into the tree. The tool extracts a thin, long sample of the tree's wood which shows the rings that formed from yearly growth. The rings can then be counted without having to cut down and kill the tree. The core sample extracted does not threaten the life of the tree.
The graduate student extracted cores from the pines but decided he could get a more accurate count by cutting down a tree. Unfortunately, the student happened to cut down what was possibly the oldest living Bristlecone pine. He determined the tree was more than 4800 years old.
With the tree cut down, cross-sections were taken from the trunk and sent to research facilities, including the University of Arizona. There is a 7-foot cross section of the tree, nicknamed Prometheus, stored at UA.
More pieces of Prometheus found their way to UA after the original graduate student passed away. Among these pieces was a part that contained the center of the tree. By putting together that piece with others that didn't have the center, a UA tree-ring scientist was able to determine the age of the pine with greater accuracy than previous efforts.
"I had never seen a piece with the pith and was curious to see where it dated," said Chris Baisan, a dendrochronologist at the Laboratory of Tree-Ring Research. "The match was really unequivocal from the first test. A reasonable age estimate is right at 5,000 years – an estimate because of the time to grow to about 7 feet, the height from which the piece with the pith came, is subject only to a reasonable guess."
Baisan believes some pines may be as old or older than Prometheus, but that none have been discovered yet.
"The odds of by chance selecting the oldest individual of a species of hundreds of thousands, or millions, of individuals spread across the rugged and remote Great Basin terrain are simply not credible," Baisan said. "I cannot believe that Prometheus was ever ‘the oldest' Bristlecone pine. As for finding an older individual," he added, "this would be a difficult and thankless task for which there is no real research incentive."
There is an ominous legend associated with Prometheus. Some people believe the wood is cursed and handling it can lead to an early death. Find out how this legend came to be in the full story here.