What We Can Learn from the Oldest Living Trees

The sky, resplendent as a shard of Navajo turquoise, highlighted the snow-draped peaks of the Sierra Nevada range. A sea of green needles and twisted limbs flanked me. I had paused on the crest of a sinuous mountain trail surrounded by most ancient beings, gnarled botanical sentinels clinging to a hillside of crumbled dolomite and scree. Birds were absent, as though they were foreigners in a land of limited biology and rugged extremes. But the trees got my attention, evolutionary stalwarts braced against the bitter harshness of this ecosystem and resilient in the face of severe environmental odds.

I had come to the White Mountains of eastern California, specifically the Ancient Bristlecone Pine Forest, to seek counsel with some of the oldest living beings on the planet. I was here to commune with Pinus longaeva, trees that have been growing steadily on these seemingly barren mountain tops ever since the development of writing in Sumer and Egypt (~2600 BCE), the beginnings of Stonehenge in what is now England (2400–2200 BCE), and the emergence of the Bronze Age in Crete (3200 BCE). Moreover, many of these same trees were well established centuries before the construction of the Great Pyramid of Giza, the introduction of rice into Malaysia, or the rise to power of the First Dynasty of Ur.

For thousands of years, most of the trees around me have been holding fast to their mountain domain, having established their botanical dominance while early human civilizations were ascending or declining in far distant lands. Indeed, as we will see, bristlecone wood has recorded Earth’s history more faithfully than any ancient Roman scribe or modern-day Twitter fanatic. They are illuminators of ancient history; open records of climate, geology, and botany; and whorled pages of data etched into ageless timber and sunburned snags. Mark A. Schlenz, a writer who has spent much time in this ancient forest, makes the point that bristlecone pines often grow in habitats utterly hostile to most other forms of plant life. He writes in A Day in the Ancient Bristlecone Pine Forest that these indomitable trees exist where it seems no trees could withstand the harsh environmental conditions of altitude, desert dryness, icy winds, heavy snows, freezing temperatures, infertile soils, and extreme solar exposure.

Great Basin bristlecone pines (Pinus longaeva) are one of a trio of long-lived pines that inhabit the American West. They can be found primarily in eastern California, eastern Nevada, and throughout Colorado’s western slope. They are famously regarded as the oldest trees in the world. Their two cousins, though less-known, are also long-lived (but not as long as Pinus longaeva). These include Rocky Mountain bristlecone pines (Pinus aristata), located in Colorado and northern New Mexico, and foxtail pines (Pinus balfouriana), which inhabit central and northern California.

The last three miles (4.8 km) to the park entrance winds through isolated clusters of bristlecone pines. Ancient sentinels, they stand against the sky. Biological and evolutionary marvels, bristlecones have laid claim to this mountainside for thousands of years and will continue to do so as long as the climate will allow them to.

Although bristlecone pines have hugged these slopes for thousands of years, their age was not known until 1953 after a fortuitous discovery by dendrochronologist Edmund Schulman. Schulman and a colleague, Frits Went, were doing research in Sun Valley, Idaho, when they came upon a limber pine (Pinus flexilis), an ancient tree about 1,650 years old. They realized that there might be more ancient trees awaiting discovery in these mountains. On their way back to Pasadena, California, they decided to make a detour and drive up into the White Mountains to check out a rumor that several very old trees inhabited the high altitudes there. Shortly after their arrival, they located a bristlecone pine tree that a local ranger had named “Patriarch.” Samples taken from the tree proved it to be only 1,500 years old. While that wasn’t as old as they hoped, it planted a mental seed: the possibility that they might find considerably older trees in the high country.

Born in 1908, Edmund Schulman grew up in Brooklyn, eventually moving to Arizona. In 1932 Andrew E. Douglass, an astronomer at the University of Arizona, hired Shulman as an assistant. Douglass was studying the relationship between sunspot cycles and climate change through an analysis of tree rings. Douglass had used tree rings to determine the age of the Pueblo Bonito settlement in the Ancestral Puebloan ceremonial complex at Chaco Canyon, New Mexico, a discovery that helped to rewrite the history of the ancient Southwest. That research was pivotal in Douglass’s securing funding to establish the Laboratory of TreeRing Research at the university in 1937.

Schulman earned a post as an assistant astronomer at the Steward Observatory. Later he took over as editor of Tree-Ring Bulletin. In 1945 he became a full-time faculty member and assumed his duties in the Laboratory of Tree-Ring Research. Schulman’s work there convinced him that he needed to return to the White Mountains, which he and his assistant C. W. Ferguson did in 1954 and 1955. They discovered that the oldest trees in this singular landscape lived in some of the most extreme conditions, typically at elevations above ten thousand feet. Most amazing was that these trees were growing in such inhospitable locales marked by lack of viable soil, extreme fluctuations in temperature, and scant moisture.

During the course of his investigations, Schulman took numerous core samples from specimens throughout this highaltitude enclave. It was then that he ventured into a grove of bristlecones near what is now his namesake, the Schulman Grove. He took a core sample from one of the gnarly trees and headed back to his camp to begin counting the annual growth rings. He counted, counted, and counted. Finally finishing in the dark of night, he counted rings beyond the year 2046 BCE. Imagine his amazement and exuberance when he realized he had discovered the first tree in the world known to exceed four thousand years in age—and it was still living. It was a scientific breakthrough of incalculable importance. Schulman named the tree “Pine Alpha.”

As it turned out, Schulman’s four-thousand-year-old tree was one of many discoveries he was to make in this area. Additional research over the years revealed scores of trees in this particular grove in the three-thousand- to four-thousand-year-old range. As many as nineteen individual trees in the Ancient Bristlecone Pine Forest exceed four thousand years of age. That is to say, nineteen trees, all still living today, germinated during the time when the Middle Kingdom began in Egypt (~2040 BCE) and at about the same time the Sumerian culture in Mesopotamia ended (~2000 BCE).

In 1957 Schulman returned to the White Mountains to sample additional trees. There he found a tree he affectionately named Methuselah, after the biblical figure who reportedly lived to be 969 years old. He estimated the tree’s true age to be near 4,600 years old. As a result, he pronounced Methuselah the “world’s oldest known living thing.” Subsequent coring and analysis of Methuselah by Tom Harlan at the Laboratory of Tree-Ring Research dated the innermost tree ring to 2491 BCE. Thus, in 2023 Methuselah’s age would be 4,514 years old. Just before his death, Schulman declared, “The capacity of these trees to live so fantastically long may, when we come to understand it fully, perhaps serve as a guidepost on the road to the understanding of longevity in general.”

Since its authentication as an old-timer, Methuselah continues to thrive along the 4.5-mile (7.2 km) Methuselah Trail in the Ancient Bristlecone Pine Forest. The tree is currently over fifty feet (15.25 m) tall and still sports healthy foliage and seed cones. It grows at an elevation just shy of ten thousand feet. For a number of years the Forest Service identified the tree with a prominent sign. However, in order to foil vandals and others prone to picking off various souvenir pieces from historical or scientific objects, its exact location has now become a carefully guarded secret. Ask one of the rangers at the visitor’s center where Methuselah is located and they will smile and most likely tell you, “Look carefully as you walk along the trail, and you will know you’ve seen it by the time you return.”

Perhaps even more amazing than Methuselah is another as yet unnamed tree that still inhabits this forest. In the late 1950s Schulman cored a certain tree there, but he never had a chance to date it before he died. Tom Harlan worked up the core long after Schulman’s passing. As of the growing season of 2023, this tree is 5,073 years old. It would have germinated around 3050 BCE—the time when humans first began to develop a writing system, known as cuneiform script, when the Early Dynastic (Archaic) period started in ancient Egypt, and when the peoples of what is now the Southwest first began to grow corn. This tree is officially the oldest nonclonal tree in the world. (A clonal tree is a plant able to reproduce itself through a process known as vegetative cloning. A clonal tree descends from and is genetically similar to a single common ancestor. Theoretically, a clonal plant can continue propagating itself for hundreds or thousands of years.) This tree’s location is another closely guarded secret.

Equally astounding as the age of these living trees is the fact that dead bristlecone pine wood also offers scientific clues about past millennia earlier than any of the living ancients in the forest. That’s because bristlecone wood that has died and fallen to the ground can remain virtually intact for thousands of years in the harsh, cold, and arid environment of these mountains. As a result, a tree’s growth rings can preserve a record of past weather patterns, climatic conditions, environmental changes, volcanic eruptions, fires, and even floods. By finding overlaps in the tree ring patterns of living bristlecones and those in fallen wood from long-dead trees, scientists have been able to identify climactic and environmental events going back to the last ice age, thus establishing a continuous chronology of environmental events for approximately eleven thousand years.

Even more remarkable is the fact that bristlecone tree rings have rewritten history. For example, in the 1960s archaeologists dated the origins of European civilization by measuring the radioactive decay of carbon isotopes in ancient artifacts. What they failed to do, however, was adjust those calculations for periodic changes in Earth’s atmospheric carbon levels. The wood from bristlecone pines provided samples that scientists could date precisely. Those scientists dated bristlecone samples by counting their growth rings; they then measured the amount of carbon-14 (C-14) in those same samples. They discovered that the radiocarbon dating process was providing dates that were too young. As a result, scientists painstakingly established a calibration factor to correct the previous dating process.

Scientists then reexamined and amended faulty C-14 data obtained before the bristlecone pine calibration. Archaeologists subsequently found that some artifacts discovered in Europe were actually one thousand years or more older than previously thought. This revision of archaeological site dates led historians to a reinterpretation of cultural diffusion throughout the Mediterranean and across Europe.

With the bristlecone pine and scientific dating methods, we have a tool that allows us to look backward for approximately one hundred centuries to a time when the world’s total population was a mere five million people (it is now just over eight billion), a time when the first bladed tools were developed, and to a time when woolly mammoths, saber-toothed cats, and giant ground sloths wandered North America, the end of the Upper Paleolithic or Late Stone Age.

                                                                    ...

Farther along the trail, I stop beside two trees standing side by side. One is most certainly dead, an ancient and gnarled snag with empty limbs and an absence of bark. The other is still living, its branches festooned with rich clumps of emerald needles. The dead one is twisted and knotted, with knobby, spindly arms sticking out in myriad directions. Its partner, the living one, cants slightly to the left. It has retained about 15 percent of its pine needles on the ends of assorted branches. Both stand proud on this mountain, as they have for eons. Who knows, perhaps they sprouted together some two to three thousand years ago. Both have weathered decades of travails and centuries of storms. One has succumbed to the ravages of time, the other clings precariously to life. Yet they are still bonded to each other, partners against the forces of nature.

For the next hour or so, I transported myself through magnificent views and the ethereal company of these mysterious friends. I passed across hillsides crowded with ancient companions, each one clinging to the soil with both tenacity and determination. Thousands of years of exposure to wind-whipped sand and denuding ice blasts have carved and stunted them. They have prospered where few other plants could ever exist. They are survivors of the first order.

And for Great Basin bristlecone pines, time is not their enemy. It is their companion.
 

In Search of the Old Ones: An Odyssey among Ancient Trees is a new book out this week from Smithsonian Books that focuses on the science and wonder of 10 of the oldest trees in the United States. Visit Smithsonian Books’ website to learn more about its publications and a full list of titles. 

Excerpt from In Search of the Old Ones Text © 2023 by Anthony D. Fredericks