Tycho Brahe, Mercury, and Retro-diagnosing Illnesses

The exhumation of Tycho Brahe seems to have captured the media attention, from the BBC’s “Danish astronomer Tycho Brahe exhumed to solve mystery” to NPR’s article “Danish Astronomer's Remains Exhumed In Prague” to everything in between:

Professor Jens Vellev from Aarhus University is leading a team of scientists who have, apparently, set for themselves the goal of determining whether or not Brahe died from mercury poisoning, either self administered or murdered. This is, apparently, the latest historical mystery that modern science is going to step in and solve. Sparing little expense, Vellev’s team will take samples from the body and test them using CT-scans, PIXE (a form of X-ray test), and according to the article at Physorg.com, a neutron activation analysis all in an effort to “help establish that Brahe’s intake of Mercury in the last weeks of his life was deadly.”

Portrait of Tycho Brahe (Source: Getty Images from the BBC’s “Danish astronomer Tycho Brahe exhumed to solve mystery”)

In 1996 tests were conducted on samples of hair that had been taken from Brahe’s body the last time it was exhumed, back in 1901. These tests indicated high levels of mercury. The mystery here is: Who administered the mercury to Brahe? Two (conspiracy) theories have been suggested: Johannes Kepler apparently killed Brahe to get his hands on Brahe’s observations and the Danish King Christain IV ordered Brahe’s poisoning because Brahe had slept with the king’s mother. Neither theory really seems all that likely.1 Moreover, it does seems unlikely that the results of Vellev’s tests will shed any light on the question of who administered the mercury.

But there is a further question that Vellev’s tests might address, but certainly assume: Did Brahe ingest a deadly dose of mercury shortly before he died? This entire project, re-exhuming the body, taking samples of hair, and testing them, was prompted by the results from the previous analysis in 1996. In this earlier analysis, Jan Pallon from Lund University was given a sample of Brahe’s mustache that had been taken from the body in 1901. Using PIXE analysis, Pallon claimed that in the 24 hours before Brahe died he had ingested a large amount of mercury. Importantly, Pallon’s test didn’t indicate the actual amount of mercury nor if that amount was fatal. He could say only that there was a spike in the mercury in Brahe’s bloodstream.2 Pallon will be part of the team that analyzes Brahe’s hair this time (see list of scientists involved).

Tycho Brahe’s coffin that was recently unearthed in Tyn (Source: Associated Press)

There is yet a broader question here: Who cares? Vellev glibly justified the project by saying “As a man of science, he’s [Brahe is] important for the whole world.”3 What, exactly, is to be gained through this new analysis? As Rebekah Higgitt has asked: “Will it really tell us much if Tycho Brahe turns out to have/not have significant levels of mercury in his bones? Will it matter?” It seems unlikely that the analysis will offer any new, or at least useful, information. But the historical insignificance of the results are just the latest in efforts by scientists to tell historians how it really was. As if realizing some twisted version of Ranke’s dictum wie es eigentlich gewesen ist, scientists have repeatedly tried to show historians that science is better at telling us about the past. The most insistent version of this must be the on-going efforts by scientists to retro-diagnose the medieval plague. An article published just last month promises settle the etiological controversy once and for all. The scientists claim to “demonstrate unambiguously that Y pestis caused the Black Death.”4 A few years ago, scientists claim to have established that the plague of Athens described in Thucydides was typhoid fever.5 And a couple years earlier scientists determined that Justinian’s plague was caused by Yersinia pestis.6 To be sure, scientists are not alone in their desire to retro-diagnose illnesses. Historians of medicine have engaged in the activity for more than a century, and there are antecedents found in medieval plague consilia themselves.

The entire project is founded on an assumption that retro-diagnosing illnesses is a meaningful activity. It is unclear why we should want to diagnose past illnesses in our modern categories. Ignoring for the moment the difficulty in interpreting historical, pre-germ theory descriptions of disease and the intractable problem of trying to reduce the plethora of ways symptoms have been described to a set of terms that are meaningful today, what historical knowledge is gained? What knowledge in general? Even if Vellev’s analysis could be successful in showing that Brahe died of mercury poisoning, does knowing that change anything? Alter our understanding of Brahe’s life and accomplishments? Detract or enhance his observation astronomy? I confess that I don’t see the benefit.

1The first of these theories was asserted in a book by Joshua and Anne-Lee Gilder, Heavenly Intrigue: Johannes Kepler, Tycho Brahe, and the Murder Behind One of History's Greatest Scientific Discoveries. The book has not received favorable reviews from the astronomy community. See, for example, Marcelo Gleiser’s review in the Journal for the History of Astronomy.
2Pallon claimed that this PIXE analysis provided information about the chemicals ingested as a function of time, especially since we know the rate at which hair grows (about 1/2” per month). Pallon concluded that the levels of mercury in Brahe’s blood increased rapidly and remained high for about 5-10 minutes and then diminished. Brahe’s total exposure had to less than an hour and occurred only a day before he died. Unfortunately, only a summary of Pallon’s paper is easily available, here.
3Vellev quoted at the Physorg.com article “Danish Astronomer’s Remains Exhumed in Prague.”
4See B. Bramanti et al., “Distinct Clones of Yersinia pestis Caused the Black Death” PLoS Pathogens 6(10) (2010); doi:10.1371/journal.ppat.1001134, available online here. While I don’t have time to analyze this article now, I hope to return to it soon.
5See M. Papagrigorakis et al., “DNA examination of ancient dental pulp incriminates typhoid fever as a probable cause of the Plague of Athens,” International Journal of Infectious Diseases 10(2006): 206–14; available online but behind a paywall here.
6M. Drancourt et al., “Genotyping, Orientalis-like Yersinia pestis, and Plague Pandemics,” Emerging Infectious Diseases 10(2004): 1585–92; available online here.