High atop the remote, rocky slopes of California's White Mountains, the harsh conditions make it difficult for life to take root. But for a certain type of tree - and for those who have traveled here to study it - this place is paradise.
These gnarled bristlecone pines are the oldest individual trees in the world. Researchers like Andy Bunn have come to learn from the ancients.
Correspondent Conor Knighton asked Bunn, "Looking at this tree, would you have any idea how old this is?"
"I've been doing this long enough to not try and play the guessing game too much," he replied. "It'd be easy for this tree to be a thousand years old; it would be easier for it to be two thousand years old. Older than that would be unusual, but not impossible."
There are bristlecones in this grove that are more than twice as old.
"It's remarkable to sit there and have your hand on one of those trees and know that it was growing when the Pyramids were built," said Bunn.
By taking core samples from the trunks - a process that researchers say doesn't harm the trees -- it's possible to extract their hidden history. "Dendrochronology" is the science of dating tree rings.
Matt Salzer, a dendrochronologist at the University of Arizona's Laboratory of Tree Ring Research, said, "Each annual tree ring is like a time capsule of the environment for that year from which it was formed. And it contains many different types of information - chemical information, the information on growth, climate information."
"If you're trying to look at people in the past through time, tree rings give you a way to do it in a way that makes sense in a human life scale," said University of Arizona professor Charlotte Pearson. She first became fascinated with the bristlecones after reading about an ancient volcanic eruption on the Greek island of Santorini. "It blew my mind that trees on the other side of the world could possibly be used to date this thing to within a single year," she said.
Massive eruptions eject so much ash that they cool the entire planet. Since bristlecones put on narrow rings during especially cold years, scientists have used those rings to help establish an eruption date of 1560 BC.
Showing Knighton a tree ring sample, Pearson said, "We're moving backwards through time here. Here we change between A.D. and B.C., and we're into the B.C. period now, going backwards through time right to the very end, where we come to 1700 B.C."
By matching up core samples from live trees with wood from dead trees, it's possible to create a record that stretches back even further.
The oldest known living bristlecone is estimated to be over 4,800 years old. Named "Methuselah," the tree's precise location inside Inyo National Forest isn't publicized, and we won't be revealing it here - scientists are worried extra attention might attract vandals. Plus, in all likelihood it's not actually the oldest.
Knighton asked, Do you believe that there are older trees out there?"
"Almost certainly," Bunn replied. "It would be naïve to think that we just happened to get the oldest tree when we looked."
Age on the inside isn't always apparent on the outside. Up a long, winding dirt road from the Methuselah Grove stands the Patriarch Tree. Though it is the largest bristlecone pine known, it's a comparative youngster, at around 1,500 years old.
Bunn said, "It really does feel like you are in the presence of something magnificent. There's not a lot of places in the world where you can get the feeling of being around trees like this."
What makes this place challenging for most species might be the secret to the bristlecone pine's success. Bunn said, "They live in this sort of moonscape where they have figured out a life history strategy where they can eke out a living in this incredibly difficult environment, and they don't really have to compete with other organisms."
For Bunn, the climate record written in the rings offers guidance for how we might think about what's happening in the present as we plan for the future. "What we're seeing increasingly is that a lot of the climate events that we are experiencing and living through right now have no precedent in the paleoclimate record," he said. "So, we really are moving into uncharted territory."
Like us, bristlecones mark time in years. Their lives are so long, these twisting sentinels see a far bigger picture.
Knighton asked, "Does it give you some perspective on your own lifespan?"
"Yeah, definitely," Bunn replied. "It gives me not only perspective of my own lifespan, but also on sort of human civilization. And to look back and to see everything that humanity's accomplished and to go back and read the rings of these trees and to think about what humanity was like at different periods while those trees were growing, is incredibly humbling."
For more info:
Story produced by Anthony Laudato. Editor: James Taylor.
Nature: Ancient trees
How John Wilson makes his acclaimed "How To" videos
Stephen Sondheim as mentor