Prometheus was a living member of a population of bristlecone pine trees near the tree line on the lateral moraine of a former glacier on Wheeler Peak, in Great Basin National Park, eastern Nevada. Wheeler Peak is the highest mountain in the Snake Range, and the highest mountain entirely in the state of Nevada. The bristlecone pine population on this mountain is divided into at least two distinct sub-populations, one of which is accessible by a popular interpretive trail.
Prometheus, however, grew in an area reachable only by off-trail hiking. In either 1958 or 1961, a group of naturalists who admired Prometheus's grove gave names to a number of the largest or most distinctive trees, including Prometheus.[3]
Currey originally estimated the tree was at least 4844 years old. A few years later, this was increased to 4862 by Donald Graybill of the University of Arizona's Laboratory of Tree-Ring Research. These ring counts were done on a trunk cross-section taken about 2.5 m (8 feet) above the original germination point of the tree, because the innermost rings were missing below that point. Adjusting Graybill's figure by adding the estimated number of years required to reach that height, plus a correction for the estimated number of missing rings (not uncommon in trees at the tree line), it is probable that the tree was at least 5000 years old when felled. That made it the oldest known unitary (i.e. non-clonal) organism at the time, exceeding even the Methuselah tree of the White Mountains' Schulman Grove, in California, though Methuselah was later redated to 4845 years old.[4]
In 2012 a bristlecone pine in California's White Mountains was measured by Tom Harlan to be 5062 years old,[4] making it the oldest known tree in North America and the oldest known individual tree in the world.
Whether Prometheus should have been considered the oldest organism ever known depends on the definition of "oldest" and "organism". Certain sprouting (clonal) organisms, such as creosote bush or aspen, may have older individuals if the entire clonal organism is considered.[5] By that standard, the oldest living organism is a grove of quaking aspens in Utah known as Pando, at perhaps as much as 80,000 years old. In a clonal organism, however, the individual clonal stems are not nearly so old, and no part of the organism is particularly old at any given time. Until 2012, Prometheus was thus the oldest non-clonal organism yet discovered, with its innermost, extant rings exceeding 4862 years of age.