April 2026: April Come She Will

One of my favorite facts is that sharks–modern sharks, that is–are older than the rings of Saturn. This is absolutely true; modern sharks are from the Early Jurassic (200 million years ago, although with some evidence stretching back to the Permian, i.e. 298 million years ago). The rings of Saturn are only 100 million years old at best. The Greenland shark, which bears the hilarious Latin name Somniosus microcephalus (sleeper shark with a small head), is also the longest lived known vertebrate, with an estimated lifespan of 250-500 years. These fascinating beasts don’t even reach sexual maturity until they’re 150 years old, and gestation takes them 8-18 years. This is life on a timescale humans can barely imagine.

I started thinking about all of this when I read about the Llangernyw Yew, which is an ancient yew in a churchyard in Wales. I have yew trees in my yard—they’re interesting plants, in part because they are very toxic. (Incidentally, Greenland sharks are also very toxic.) Also, yews are apparently very good at not dying. The Llangernyw Yew is about five thousand years old. It is not unique in its age—the Fortingall Yew is another ancient yew of perhaps the same vintage that lives in Scotland. And these are not the oldest living organisms on the planet—they’re not even the oldest living trees!

At some point in all of this, you start running into problems of how we measure age. For example, the heartwood of yews tends to rot, and in many ancient yews that wood has been removed, which makes it difficult to date the tree using methods such as counting rings. For very old clonal trees, sometimes scientists find fossilized pollen in nearby areas and can compare the genome—but is a clonal tree the same as an individual tree? A clonal tree reproduces by creating genetically identical clones of itself. Though some die and new ones sprout, the organism remains the same(?). Some clonal tree systems(?) have existed for ten thousand or sixty thousand years, but the individual trees within that system are only a few hundred years old at best. Even the roots die and are replaced over time. This is essentially the Ship of Theseus problem, but a tree; Pando, for example, is a colony(?) of quaking aspen in Utah made up of something like 47,000 separate stems, all of which are genetically identical. The tree(?) has been there for perhaps 16,000 years, meaning it was already an old organism by the time of the Clovis culture (11,100 BCE).

Humans tend to look at life on a very small timescale. I’m usually much more concerned about what I’m going to have for lunch than with what the world is going to be doing in two hundred years. But sometimes when times get stressful, it’s nice to remind myself that there are many other ways to experience life. Those sharks live through all the same minutes as I do, but they mean different things to them. (I mean…if minutes can mean anything to a shark. Someone call a philosopher and a zoologist.) At the same time, Notre Dame and Angkor Wat went up during the life of our shark’s grandparents, though they may hasve been unaware, and during her parents’ lifetime, so many things happened—Shakespeare, the Qing dynasty, the scientific revolution, the fall of the Aztec empire. The shark of our generation may have seen telegraph wires cross the ocean, telephones, and space travel. Who knows what she’ll see a century from now? Political situations—good and bad—come and go, but the shark persists. I like that.