In 1864 a Canadian geologist believed he had discovered the remains of the first life on Earth. The microscopic fossil was found deep in rock layers that most geologists thought were devoid of life. The man who discovered the fossil, John William Dawson, soon garnered the interest of Britain's most eminent geologists. He named the fossil Eozoön canadense or the "dawn animal of Canada", and so began a controversy that lasted more than three decades.
Possibly fewer scientists would have taken notice of Dawson's fossil had it not been so old. Some, such as Charles Lyell, saw the fossil as evidence for Charles Darwin's theory of evolution. The age of the fossil seemed to extend the period of time that life had existed on Earth and therefore to provide more scope for slow evolutionary change. Eozoön was soon the talk of the scientific societies in London, Canada and the US.
Excitement about this "firstling of creation", as one scientist dubbed it, encouraged further investigations. Illustrations show an unremarkable organism that consisted of hollow tubes and looked a bit like a modern coral. Eozoön, or fossils like it, were quickly discovered in geological strata in Germany, Bohemia and Ireland. The Irish fossils proved to be the undoing of Eozoön.
A pair of scientists in the newly founded Queen’s College Galway – now NUI Galway – were also interested in the new discovery. Upon reading that the fossils had been found in Connemara marble, William King and Thomas Rowney decided to see for themselves. They searched in vain. What they saw in the rocks were not fossils, just the relics of chemical and physical processes. Those who thought these were fossils, they wrote, had accepted “on mere authority a plausible yet one-sided explanation of a difficult problem”.
In fact, Eozoön presented several difficult problems. The first was its age. Such an ancient fossil challenged the idea, accepted by many scientists at the time, that life on Earth was relatively recent. The Canadian geological strata, or layers of rock, to which it belonged had analogous strata on other continents and all had been thought to be devoid of life. The second problem was that seeing Eozoön required looking through a microscope. This was a very personal act of observation, potentially unique to each observer. Microscopic photography was in its infancy; the science of vision suggested that the process of seeing was extremely complex. How could any individual scientist be sure that what they saw under the microscope was "real"?
Those who did not believe in Eozoön exploited these uncertainties. They claimed that the fossil's supporters had clouded vision and saw only what they wanted to see. The fossil seemed almost too convenient for advocates of evolution by natural selection. As one scientist put it, "The Darwinian theory wanted a cornerstone: and there it was." It did not help when an organism dredged from the bottom of the ocean and thought to be related to Eozoön turned out to be nothing more than a reaction between sea water, animal remains and alcohol.
Science works today and worked then by reaching some kind of consensus. I can come up with any theory I like, but it will gain credibility only if other scientists agree. But the Eozoön controversy reminds us that in the debates required to reach consensus, not all scientists are treated as equal. King and Rowney were dismissed as lacking sufficient authority to support their claims: Eozoön was supported by "the many accomplished naturalists of this metropolis", while it was "denied only by a Galway professor". That might have been the end of that. Instead, the "Galway professors" refused to stand down, and support for the fossil began to ebb away.
I do not mean to suggest that truth eventually triumphs, but that debate is the heart of science. Without debate, we are left with “mere authority”.
- If you want to join in some of the debate about the history of science, technology and medicine, come along to the inaugural conference of History of Science, Technology and Medicine Network Ireland at NUI Maynooth this November. hstmnetworkireland.org
Juliana Adelman lectures in history at St Patrick’s College, Drumcondra