On the way home from Escalante, where my mother, my sister, and I had made a short trip out of a long hike to the Cosmic Ashtray, we took a small detour to Fishlake National Forest in central Utah to stretch our legs and visit the aspen grove Pando.
For its age, size, and fragile beauty, Pando has become one of Utah’s many icons. But beyond all that, this aspen grove may also reveal a lacuna, a missing piece, of evolutionary theory—something at the level of the very metaphysics we use in thinking about ecosystems.
Among the trees, the quiet was unfamiliar. Standing at the surface, glimpsing just one moment in an unfathomably long process, Pando was sublime—but not obviously remarkable from a scientific lens, especially not from theoretical biology. What appears to be an isolated grove of individual trees was in truth one large organism—a contender for the most massive organism, in fact, having grown and sustained itself throughout millennia. Its name, Pando, comes from the Latin “I spread,” owing to its growth and size: 47,000 trees fully integrated through a root system, covering over 100 acres. Such aspens persist as runners from the root system pierce the topsoil, forming new stems.
A population and an individual seem to us like essentially different things. But consider Pando; that difference seems less significant. Pando is a clonal organism, but since the clones remain integrated, we intuitively label it an individual. If each aspen tree were separate from the root system, we then would call Pando a population, an ecosystem. Ecologically, however, we find there is little difference between the functioning of a fully integrated colony and a “splitting” colony.
Our senses do not mislead us into thinking Pando is a forest, as a forest is precisely what Pando is. It does the sort of things we expect a forest to do: spreading, evolving, and persisting. New leaves come and go each year; trees sprout, age, and die. The turnover of trees and cycling of material has been constant since at least the ice age, with no tree more than 200 years old. Each stem inherits something of the stems before it that isn’t rooted in genes. So, the problem is this: this forest ecosystem has a population of 1, and there is no reproduction.
Population and reproduction are central to standard accounts of ecosystem evolution; thus, the sort of thing Pando is—an individual, not a population—generates not only biological but philosophical questions. Can genuine evolution occur within a single generation?
The branch of philosophy concerned with understanding what things are at the most basic level is metaphysics. Metaphysics is the field of inquiry concerned with the nature of things: what things exist and their kinds. While the fundamental metaphysics of reality, I believe, is cognitively inaccessible, the field can offer insight when in conversation with the sciences. This uncertainty around our understanding of evolution is one such example.
Ecosystems evolve—they change. What explains this change? Under the standard accounts of ecosystem evolution, reproduction of individuals in a population is the central process. In the language of metaphysics, reproduction is a process, while our understanding of the individual organism reproducing is a substance. Process and substance are two distinct metaphysical categories, analogous to the universal distinction between verbs and nouns in human language. Processes do things. Substances are made of things.
This is as well as I will explain the distinction, as attempting to define “process” would bring more confusion than clarity. It is not obvious, but this distinction is particularly relevant to questions of identity, scientific interest, causality, religion, and ethics—but I won’t get into these.
We often think about (model) individuals like boulders cascading down a cliff, where the surface changes through constant impact but the underlying core remains, and the sum of all these boulders is a thing made of boulders (by construction). The case of aspen trees reveals a more fractal-like reality. The individual is its own cascade, so to speak.
To the philosopher Frederic Bouchard of the University of Montreal, the aspens like Pando demonstrate the necessity to shift evolutionary theory from focusing on population and reproduction to variation and persistence. While aspens can reproduce sexually, their intragenerational processes appear to be aimed at doing something different while still doing something right. By focusing solely on reproduction in evolutionary explanation, we get an incomplete picture. This isn’t meant to diminish evolutionary theory but to expand it and free it from metaphysical baggage inherited from early genetics.
Stepping back, when we reflect on ourselves and our interactions with non-human life, this shift seems right. Although Bouchard’s suggestion that persistence drives adaptation challenges something sacrosanct to many views of evolutionary theory, should it come as a surprise? Familiar human systems—which are still natural systems—don’t seem to us to evolve exclusively through processes of birth and death; the power of human creativity is in ourselves. We are made of motion. We breathe, metabolize, mature, and age, and yet we remain the same person through it all. We don’t move through time; we are time itself. So, it is for all of life.
Now, Pando hasn’t been doing so well lately. It shows signs of decline, believed to be caused by deer consuming young stems and insects and disease beleaguering canopy trees. Can what we have just learned help? The metaphysics of process have a role to play in conservation, but I have not worked out how it would look in Pando’s case and invite creative people to consider this challenge.
Ultimately, in a world of process, all things are ephemeral. Ephemerality does not mean complacency; we should do what we can to preserve and foster the living world around us. Though there are signs of decline, Pando will continue persisting well into the future, barring an act from God—or humanity. But the sense of the transience of things can be felt in the air beneath the branches. For its motion and the insights into the nature of things that it has given us, let’s cherish our Trembling Giant.
