​In 1964, Donal Rusk Currey killed the oldest tree ever. To this day, there has still never been an older tree discovered. The tree was a Great Basin bristlecone pine, and Currey didn’t meant to kill it. It was an accident, and one he didn’t really understand the ramifications of until he started counting rings.

Radiolab told Don Currey’s story in their Oops Episode:

Basically, Currey got his tree corer stuck in the tree. So stuck that it wouldn’t come out. An unwitting park ranger helped him by cutting the tree down, to remove the instrument, and later Currey began to count the rings. Eventually, he realized that the tree he had just felled was almost 5,000 years old – the oldest tree ever recorded.

The story is a sad one, but there’s a lot of science in there too. Great bristlecone pines are some of the longest living trees in the world. In the 1950s, this was a shock to people, who always thought that for trees, longevity correlated with size. Bristlecone pines max out at around 20 feet tall—they’re gnarly, little gnomes of trees, nothing like the majestic Redwoods of California. Collectors Weekly explains how they live so long:

Even if a large portion of a bristlecone is damaged by erosion or fire, small strips of living bark, which Schulman called “life lines,” are able to function and keep the tree alive. “Bristlecones will grow a thousand years or so, and then the bark will start dying off on one side,” says Tom Harlan, a researcher at the Laboratory of Tree-Ring Research at the University of Arizona. “Therefore, the tree can’t support the branches directly above that area, and they die. Pretty soon you’re left with a small strip of bark, which is supporting all of the foliage. It might be only 2 inches wide, but the pine is still considered a growing, healthy tree.”

It’s also worth noting that figuring out how old a tree is, isn’t that easy. Dendrochronology—the fancy word for tree-ring dating—didn’t come around until the 1890s. And it’s more complicated than just counting rings, since each ring doesn’t necessarily correspond to a year. The University of Arizona’s Laboratory of Tree Ring Research explains:

Ring-counting does not ensure the accurate dating of each individual ring. Numerous studies illustrate how ring-counting leads to incorrect conclusions drawn from inaccurate dating. Dendrochronologists demand the assignment of a single calendar year to a single ring. Various techniques are used to crossdate wood samples to assure accurate dating.

The tree Currey felled has been nicknamed the Prometheus tree. Collectors Weekly writes:

The Prometheus tree’s felling made it doubly symbolic, as the myth of its namesake captures both the human hunger for knowledge and the unintended negative consequences that often result from this desire. Though members of the scientific community and press were outraged that the tree was killed, Currey’s mistake ultimately provided the impetus to establish Great Basin National Park to protect the bristlecones. The death of the Prometheus tree also helped to change our larger perception of trees as an infinitely replenishing resource. “It’s not going to happen again,” says Schoettle. “But it wasn’t something that I think they struggled with at the time, because it was just a tree, and the mindset was that trees were a renewable resource and they would grow back. And it didn’t seem like it was any particularly special tree.”

Now, Currey almost certainly didn’t fell the oldest tree ever. There are forests in the White Mountains, and elsewhere, where trees currently standing are probably far older than his Prometheus tree. We just don’t know about them.

Update February 10, 2016: Since this article was written, an older tree was identified in the White Mountains, California. The tree is also a bristlecone pine and is thought to be over 5,000 years old.