By Leah Duran
The world's oldest-known tree — a Great Basin bristlecone pine — began stretching toward the sun 4,740 years ago when Egypt's pyramids were being built. Methuselah, named for the oldest person in the Bible, grows in a secret location in eastern California's Inyo National Forest and still yields fertile seeds.
Northern Arizona's San Francisco Peaks harbor an isolated population of Rocky Mountain bristlecone pines, one of two species of this long-lived tree. In 1984, tree rings revealed one specimen in the Flagstaff area to be 1,438 years old — dating to the height of Mayan civilization.
These ancient trees thrive in subalpine forests on dry, rocky slopes and ridges ranging from 9,500 to 12,000 feet in elevation. Harsh conditions, such as cold temperatures and acidic, nutrient-poor soil, reduce the risk of fire. They also cause bristlecone pines to grow slowly; after several centuries, their twisted trunks reach a mere 20 to 40 feet tall. On older trees, reddish-brown bark with deep creases abuts dead limbs.
Core samples of bristlecone pines provide insight into Earth's historic climate, as these resilient trees modified their growth patterns based on seasonal and yearly changes throughout millennia.