Darwin’s First Theory; Exploring Darwin’s Quest to Find a Theory of the Earth by Rob Wesson. Pegasus Books, 2017.
Charles Darwin is best known for his On the Origin of the Species by Means of Natural Selection. His “first theory” however was an important contribution to the science of geology. He received an invitation to participate in the voyage of the HMS Beagle, from 1831 to 1836. Its purpose was to explore and map the coasts of Argentina and Chile. Part of that long voyage was spent hiking through the Andes on field trips.
Darwin was still a young man, twenty-two, having just completed his studies at the University of Edinburgh and Cambridge. He hadn’t yet married, nor established a career. Rob Wesson suggests that he considered his selection to be a big honor. But he needed to bone up on his geology and so he engaged in a ramble through North Wales with a noted geologist, Adam Sedgwick.
Darwin’s cabin mate on the HMS Beagle was Robert FitzRoy, an English officer in the British Royal Navy and captain of the ship. They got along well, though FitzRoy was already showing signs of the depression from which he would suffer later in life.
FitzRoy, like many other scientists who read Darwin became alarmed when his theories were less not easily reconciled with the creation accounts in the Hebrew Bible. True, Biblical stories about a catastrophic flood in the creation of Earth did not necessarily conflict with observations that Darwin and others were making about natural phenomena, particularly of tsunamis, earthquakes, and volcanic eruptions. (Tsunamis were in Darwin’s time called tidal waves.) But Darwin was creating a new language that was less and less confirming of the Genesis account.
After their voyage Darwin and FitzRoy were invited to give papers and take part in the discussion of their observations of the coast of Patagonia at the Royal Society. This prompted an often heated discussion over the next half-dozen years about Darwin’s “first theory.” Charles Lyell, British lawyer and geologist, joined the conversation arguing for what he, and Darwin and other geologists referred to as Uniformitarianism – the theory that Earth was shaped by the same processes still in operation today. Lyell popularized the idea of uplift and subsidence, which fit well into Darwin’s observations of the presence of coral reefs now visible well above the surface of the ocean.
Wesson has captured an edifying portrait of the lively scientific community in Britain in the mid-nineteenth century. They were not necessarily associated with the country’s universities. There were now many professional organizations that you could be invited to join. Papers were given in rooms of some social clubs if the organization itself did not have a club room.
One of the topics of conversation was “erratics.” These were boulders that were “out of place” and had somehow gotten to their locations by some mechanism, not yet well understood. Some geologists suggested that they were brought to their location by icebergs. The possibility of glaciers transporting them had not yet been proposed because there was no clear understanding of glaciers and what we call the ice age.
The idea of an ice age also explained another geological puzzle that these geologists, including Darwin, found quite mysterious. Called the Parallel Roads of Glen Roy, they were once the various shorelines of ancient, ice-jammed lochs. But there was no sign of what might have blocked the valley to create those various shorelines. Again glaciers became the proposed solution.
There was as yet no speculation on drifting continents, subduction and uplift, although Darwin and his generation had begun to describe the phenomena. Darwin was also beginning to think about species and the mechanism of natural selection that would explain their diversity. We would call this thinking about geological and biological phenomena “thought experiments.”
Wesson’s book is about Darwin’s “first” theory, not about On the Origin of Species. That explains why the famous letter from Alfred Russel Wallace proposing the same mechanisms that Darwin was considering. Wallace’s paper on the subject was jointly published along with some of Darwin’s writings in 1858. Finding out that the idea of natural selection was circulating amongst naturalists prompted Darwin to publish his Origin.
Darwin’s theories were much discussed in Great Britain because he was also an accomplished writer. And there was already a conversation going on about his first and subsequent theories that drew in Wallace, Lyell, Adam Sedgwick, and other geologists and biologists.