Hundred-year-old causes of death mapped: ‘The past is the laboratory of the present’
If it is up to university lecturer Evelien Walhout, in a year's time we will know exactly what people from Haarlem and Zwolle died of a century ago. Together with colleagues from other universities, she started the doodsoorzaken.nl platform, where causes of death are recorded. ‘Somewhere around the turn of the century, you see a transition from epidemic diseases to diseases of affluence as the main cause of death.’
Since 1865, municipalities have been required to record the causes of death of their residents. With today's digital resources, that data is a goldmine for demographic historians like Walhout, who want to look for patterns in those deaths - if municipalities have kept the data, at least. ‘Unfortunately, you see that many municipalities have only kept the data in aggregated form and have destroyed the individual death certificates,’ Walhout says. ‘So far, we haven't found anything for Leiden, for example.’
In cities like Amsterdam, Maastricht, Zwolle, Haarlem and Roosendaal, among others, the causes of death did end up in the archive. ‘Over the past five years, we researchers from Nijmegen, Groningen and Leiden, together with volunteers, have digitised all the data from Amsterdam,’ says Walhout. It was a massive job, where each volunteer retyped a scan of the handwritten registration, then the same scan was copied again by another volunteer and the two results compared. And that times six hundred thousand!’
Mechanism unravelled
‘It’s a huge amount of work,’ Walhout admits, ‘but such a large dataset allows us to see how different infectious diseases interact. Earlier research has been done on cholera, for example, but only looking at that one disease. Now, for the first time, we can map the relationship between different infectious diseases and unravel the mechanism behind it. So, the past acts as a laboratory for the present, which can also yield interesting parallels with COVID, for example.'
In addition, the researchers are interested in what is known as the epidemiological transition: the transition from infectious diseases as the main cause of death to diseases of affluence such as cancer. ‘That took place in the late nineteenth, early twentieth century,’ says Walhout. 'We would like to know exactly how it took place. Which groups benefited from it first?'
To answer those questions, it is useful to compare the Amsterdam data with data from other cities. ‘Haarlem is in the same region, but it’s much smaller,’ Walhout explains. 'Then you can nicely see the influence of the city's size, while Zwolle on the other side of the country has a completely different working population. That leads to a different kind of society, just like the Catholic character of Maastricht and Roosendaal, for example.'
Network full of knowledge
So the volunteers are doing more retyping. They discuss their most interesting finds on a private forum. Walhout: ‘Among the volunteers are many retired doctors, who have a lot of knowledge that we as researchers eagerly make use of. At the same time, you see that they themselves also get to work with the new information they acquire. Several booklets have already been published by volunteers, for example about people who died in bombing raids in World War II.' Whole families dying are also often remembered. ‘That continues to stir the emotions, even so many years later.’
The causes of death from Haarlem, Zwolle and perhaps other cities in the future are registered on doodsoorzaken.nl.