It’s taken me a while to get into, since in a stroke of confusing genius the editor of the book decided to open it with several essays on statistics (a subject by which I’m fascinated) that used extensive baseball analogies (a sport about which I know next to nothing). After having slogged through them in constantly slight confusion, I’m now finding it an absorbing read.One particular essay, “worm for a century, and all seasons” sucked me in completely as it documented Darwin’s last book, a treatise on earthworms of all things! According to Gould’s essay, Darwin’s detractors often criticised him for the triviality of his chosen subjects, but what they failed to realise was that the choice of such a humble subject was deliberate, and demonstrated a powerful principle.Darwin shows that the leaf mold we’re used to seeing on the top of soil is almost entirely created by earthworms, (of which there were over 53,000 per acre where Darwin was gathering his evidence!). As they eat and excrete, rendering down new surface material, the previously created mold is compacted underneath, and slowly sinks, as new mold rises above it. You can follow the progress of a single stone as it sits on the surface, and then sinks into the soil over time (about an inch every 12 years), and the amazing thing is that this process is so uniformly constant, that the depth of currently un-compacted leaf mold barely changes, and the ground sinks in perfectly parallel layers.
This I assume is the reason that the time-team always found the archaeological evidence they were looking for a good way under the soil, and why they talked merrily about different bands of soil representing different eras. I always wondered what process made for such a convenient and confusing arrangement, and the answer is stunning… earthworms! It’s at once charming, absurd and a little creepy to think that vast armies of earthworms marching across time shape our hills and fields.
The principle Darwin sought to illustrate with his humble, pink wriggly subjects is tricky to describe, but powerful in practice.
As early geographers looked about them, they saw grand landscapes, huge mountains, massive canyons and deep seas… in short a land that looks scarred by the most catastrophic forces imaginable. And that is literally the conclusion that many came to in a school of early geography known as catastrophism, in which all sorts of global disasters such as Noah’s flood were invoked to explain the earth’s current state. But, in order to practice geography scientifically, we needed more than speculation: we needed observation! However, we couldn’t see into the past, and all the processes we observed around us (even the largest floods and volcanoes) were like the barest touch of a feather as far as the earth was concerned! Where could we turn to observe the immense forces that must have carved something like the grand canyon?
It’s incredible to realise that until the 1800s, no one had grasped (or at least recorded) the concept that tiny forces could – over vast areas and vaster spans of time – add up to the appearance of catastrophic effect. We now call these incredible tracts of time ‘geological’ only because geologists realised they needed to be that immense to adequately explain what we observe today without invoking the divine and unobserved!
According to Gould, Darwin’s books (excluding The Origin of Species) each took meticulously studied examples to illustrate grand principles. His examination of coral reefs illustrates where we turn when the forces are slower than even the worms and cannot be observed in a single lifetime. Roughly speaking, there are three states of coral reef:
If we choose not to see them as three arbitrary arrangements of reef and island, but as three freeze-frames of the same process initiated at different times in the past, we suddenly see the island sinking as the reefs rise over immense stretches of time! Thus we arrive at another principle for observing now what we can never hope to witness in movement.
I was captivated by this concept, and stopped on the sentence “Darwin used it to explain coral reefs.” to talk enthusiastically with Kate about it, explaining as I did my realisation that this could be seen as the underlying principle of our entire understanding of the universe! As we look out at the stars, the further we look, the older the objects appear (since the light from them took longer to reach us). What incredible luck! We have a snapshot of the universe at every visible age, growing older as we see further, documenting the development of the entire cosmos for our insignificantly minute eyes.
As Kate and I were finished discussing, I glanced down to read on and to my delight the next sentence was “We invoke it today to infer the history of stars”.
I love reading :)