Studying how the evolutionary process has affected and continues to affect human life-history variation requires collecting data across the lives of individuals, but this is extremely impracticable in contemporary populations. Historical records are a way of collecting large volumes of data on human life-histories, especially church records, because they contain data on all the relevant life-history parameters: births, marriages, and deaths.
In 1749, the King of Sweden, of which Finland was at that time a province, decreed that the Lutheran church was to document all births, marriages, deaths and migrations across the country, for the purpose of maintaining better tax records. The result is a wonderful series of data sets which can be used to answer questions related to life-history variation in humans, with associated data sets on climate, crop yields and epidemics.
Virpi Lummaa has compiled a dataset of over 100,000 individuals, born from the seventeenth century to the present, from parishes in the south-west of the country. This is a population with no medical care, no access to contraception and therefore exhibiting ‘natural’ rates of mortality and reproduction, offering the opportunity to answer questions related to how unusual human life-history patterns evolved. For more information on the data, some pictures(!) and the range of questions which have been answered, visit Virpi’s website.