Bristlecone Time: Jonathon Keats's Clock That Measures Time by a Tree's Growth
The Long Now Foundation
Centuries of the Bristlecone asks what a standard of time would look like if it came from a living thing that measures its life in millennia rather than from atomic precision. The project centers on a clock driven by data from bristlecone pines in eastern Nevada. Its argument is that our pursuit of exact, universal time has cost us something, and that other ways of keeping time deserve our attention.
From Natural Cycles to Coordinated Universal Time
The film opens by noting that for thousands of years, humans kept time by watching natural cycles. Spring was not a fixed date on a calendar. It arrived when a certain bird migrated, an insect began to sing, or a wildflower came up out of the ground. Over time, people made calendars more regular. Today society follows Coordinated Universal Time, calibrated to a billionth of a second.
The narration argues that something has been lost in this shift. It poses two questions that frame the project: what a new standard of time might look like, and what time would mean to a life form that measures it in millennia.
The Bristlecone Pine as a Natural Calendar
The answer comes from a remote mountain in eastern Nevada, where the bristlecone pines grow. The film describes them as having lifespans approaching 5,000 years, which it says makes them the longest-lived complex organisms on Earth. They have outlasted civilizations, and each limb has been shaped by centuries of ice and drought. For these reasons the film calls them ideal natural calendars.
Precision Is Not the Same as Accuracy
Keats distinguishes between precision and accuracy. He says we are always trying to make time more precise, but that precision is not necessarily accurate. In his view, ever-finer timekeeping creates the illusion that the whole world can be controlled to suit our needs. The project is built as a response to that illusion. At its core is a clock meant to offer an alternative to Coordinated Universal Time, a standard Keats calls "bristlecone time."
How Bristlecone Time Works
Bristlecone time measures time by girth rather than by fixed intervals. A tree grows one ring each year, but the thickness of that ring varies from year to year with climate conditions. When time is tied to growth, a year of greater growth moves the clock forward faster. Keats describes this as a way to tell time from the tree's perspective, and he calls the clock an instrument that helps us orient and calibrate ourselves in relation to the tree.
The data come from trees on the Long Now Foundation's Bristlecone Preserve. The film describes that data as becoming a rhythm, "a heartbeat," that directs a clock located at the Nevada Museum of Art.
The clock face shows two times side by side. On the left is Coordinated Universal Time. On the right is bristlecone time, which the film says will slowly drift out of sync with Gregorian years. The narration stresses that each is correct. The project does not present one standard as true and the other as false. It presents them as different ways of keeping time.
A Clock Built for Future Generations
Other voices in the film talk about the clock as an object meant to last. One speaker says that such objects build "bridges of empathy" over time and across time, and that this may be one of their most important roles in history. The clock is described as having "centuries of intention." Its makers say they are building something meant to endure, to be engaged with, and to be held by future generations.
The same speakers connect this to how we think about past and future, calling the two "two sides of the same coin." They say they hope people will engage with the clock in a big way, and even calibrate their lives around it in some sense.
Many Standards of Time
The film ends with a caveat. As Keats notes, trees have no use for clocks, because they are already perfectly good at keeping time themselves. The clock is for humans. Keats hopes that recognizing bristlecone time will help people notice the time kept by every entity they encounter, what he calls the millions of time standards around us when we stop to pay attention. The film's closing line states its conclusion: "Ultimately, we all need to make time together."
For thousands of years, humans kept time by observing natural cycles. Spring wasn't a set day, but when a certain bird migrated or insect sang or wildflower emerged from the ground. Gradually people made calendars more regular. Society now follows what's called Coordinated Universal Time, calibrated to a billionth of a second.
But something has been lost by this new standard of time. What might a new standard of time look like? What would time mean to a life form that measures it in millennia?
High on a remote mountain in eastern Nevada live the bristlecone pine. With a lifespan approaching 5,000 years, these trees are the longest lived complex organisms on Earth. They have outlasted civilizations. Each limb sculpted by centuries of ice and drought. They are ideal natural calendars.
We are always on a quest to make time more precise. But that precision is not necessarily accurate, because it leads to the illusion that the entire world can be controlled according to our needs.
The other question at the core of Centuries of the Bristlecone is a clock that provides an alternative to Coordinated Universal Time. I call this new standard bristlecone time. If time is measured in terms of girth, greater growth will advance time more quickly. Every year, a tree will grow a ring. But the thickness of the ring changes from year to year based on differences in climate conditions.
Bristlecone time provides a way to tell time from the tree's perspective. The clock is an instrument to orient us, to calibrate ourselves in relation to the tree.
The data drawn from these trees on the Long Now Foundation's Bristlecone Preserve becomes a rhythm, a heartbeat that directs a clock located in the Nevada Museum of Art.
I believe one of the most important things and the roles that these objects play in our history is that they build bridges of empathy over time, across time. This clock does have centuries of intention. And so we are building something that is meant to be around and meant to be engaged with, meant to be held by future generations.
The clock shows two different times. On the left, Coordinated Universal Time. On the right, bristlecone time, which will slowly grow out of sync with Gregorian years. Each is correct.
Thinking about the future and thinking about the past, they're really two sides of the same coin. Our intentions now are that we are building things for the future. We are making something that we do intend to be engaged with in a big way, that we hope people will calibrate their lives around, in a sense.
Of course, trees have no use for clocks. They are perfectly good at keeping time themselves. I hope that recognizing bristlecone time will help us notice the time kept by each entity we encounter. The millions of time standards that surround us when we stop to pay attention. Ultimately, we all need to make time together.
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