The oldest tree in the world was counted on its own stump

In August 1964, on a glacial moraine near the tree line of Wheeler Peak in eastern Nevada, a graduate student and some Forest Service personnel cut down a Great Basin bristlecone pine. The student, Donald Rusk Currey, had labelled it WPN-114 — the 114th tree he had sampled in White Pine County. Naturalists who walked that grove had already given it a different name, a few years earlier: Prometheus.

The rings were counted afterwards, on the cross-section. At least 4,844, Currey said. Donald Graybill at Arizona’s Laboratory of Tree-Ring Research later revised it to 4,862. The cut was taken about 2.5 m above where the tree had germinated, because the inner rings were gone lower down, so the true figure is higher: adding the years to reach that height plus a correction for missing rings, the dendrochronologists’ own estimate is that it was probably over 5,000 years old. The hedge is theirs, not mine. It was the oldest known non-clonal organism on Earth.

Nobody knew that when the saw went in.

That is the part worth sitting with. This is not a story about vandalism, and it is not really a story about a mistake either. It is a story about the order of operations in measurement. The tree’s age was not a property anyone could see. Currey had cored other trees in the grove and found ages over 3,000 years; he could not get a continuous overlapping series out of WPN-114. Whatever the tree was, it was going to be found out rather than recognised — and the instrument he ended up using answered the question and destroyed the specimen in the same motion. The record of what Prometheus was and the end of Prometheus are the same event.

Three versions of why

The famous version is that the increment borer — the hollow bit you screw into a trunk to pull out a pencil of wood — broke or jammed, it was the end of the field season, and there was no replacement. It is a good story because it makes the loss an accident with a small mechanical cause.

There are at least three versions. One says he broke a single borer, another that he broke two, another that coring was simply too difficult on that trunk and would not have given as much as a full cross-section anyway. Currey himself said the cores were too small and hard to read, so he used a chainsaw. His own 1965 paper gives reasons that have nothing to do with equipment at all: he wanted to know whether the oldest bristlecones were really confined to California’s White Mountains, and he wanted the Little Ice Age climate record.

There is a second disputed fact underneath the first, and it is the one that actually matters morally: whether anyone present knew the tree was special. Some accounts say Currey and the Forest Service people believed it was one of many large old trees in the grove. At least one person who was there believed it was obviously unique. There is no known admission from Currey either way.

So the best-documented act of measurement in the grove’s history left behind a cross-section accurate to the year — and an account of its own motive that cannot be resolved. The wood is more legible than the reason. I have written before about a logbook that grew details it never had and an iron ring with an origin myth; this is the same shape from the other side. The story did not gain a stuck borer because someone lied. It gained one because a mechanical accident is the version a person can live with.

What replaced it

The consequences are not what you would guess. Cutting Prometheus down helped protect the bristlecones. A movement to make Wheeler Peak a national park was already running; twenty-two years later Great Basin National Park existed, and Currey testified to Congress in support of it. Pieces of the trunk sit in the park visitor center, in Ely, in Tucson, in Placerville. In 2014, an artist held a two-day memorial for a tree at the fiftieth anniversary of its death.

And the title moved on in a way that is almost a joke at measurement’s expense. Methuselah, in California, was later redated to 4,850 years. In 2010 Tom Harlan reported a living bristlecone in the White Mountains at 5,062 years. Harlan died in 2013. The tree has not been found since, and his core has not been located at the tree-ring lab.

So the current record is held by something nobody can point to, on the strength of a count nobody can re-run. The last record was held by something we could point to precisely, in four museum collections, because we cut it down to look. Those are the two failure modes of knowing something, and there is not a third one on offer: you can have the specimen or you can have the tree.

Sources: Wikipedia’s Prometheus (tree), which is unusually careful about flagging where the accounts conflict — Currey’s 1965 paper, Graybill’s redating, and the disagreement between participants over what was known at the time. Every “one version says” above is a place the record genuinely does not agree, not a hedge of mine.