The bristlecone pine is a type of pine tree (Family Pinaceae) that can reach an age far greater than that of any other living thing known - up to 5,000 years. There are two related species. The Rocky Mountain bristlecone pine (Pinus aristata) found in Utah and Colorado, — specimens have been found up to 3,000 years old. The recordholder, however, is the Great Basin bristlecone pine (Pinus longaeva). One named "Prometheus" was cut down in 1964 in an area now protected by Great Basin National Park in Nevada. Its rings were counted (not easy because the trunks are very twisted and distorted), and its age determined to be about 4,900 years old. "Prometheus" did not die just to have its rings counted. The carbon content of the wood from its various rings was analyzed, providing an important calibration for radiocarbon dating.

Currently, the oldest living bristlecone, "Methuselah" is located in California and is believed to be about 4,700 years old, although there certainly could be older specimens in remote parts of Nevada.

Bristlecones grow in isolated groves just below timberline. Between cold temperatures, high winds, and short growing seasons, the trees grow very slowly. The wood is very dense and thus resistant to invasion by insects, fungi, at other potential pests. As the tree ages, much of its bark dies, typically leaving only a few strips of living tissue to connect the roots to the handful of live branches.