Mortality Risk and Survival in the Aftermath of the Medieval Black Death

<div><p>The medieval Black Death (<i>c</i>. 1347-1351) was one of the most devastating epidemics in human history. It killed tens of millions of Europeans, and recent analyses have shown that the disease targeted elderly adults and individuals who had been previously exposed to physiological stressors. Following the epidemic, there were improvements in standards of living, particularly in dietary quality for all socioeconomic strata. This study investigates whether the combination of the selective mortality of the Black Death and post-epidemic improvements in standards of living had detectable effects on survival and mortality in London. Samples are drawn from several pre- and post-Black Death London cemeteries. The pre-Black Death sample comes from the Guildhall Yard (n = 75) and St. Nicholas Shambles (n = 246) cemeteries, which date to the 11^th–12^th centuries, and from two phases within the St. Mary Spital cemetery, which date to between 1120-1300 (n = 143). The St. Mary Graces cemetery (n = 133) was in use from 1350–1538 and thus represents post-epidemic demographic conditions. By applying Kaplan-Meier analysis and the Gompertz hazard model to transition analysis age estimates, and controlling for changes in birth rates, this study examines differences in survivorship and mortality risk between the pre- and post-Black Death populations of London. The results indicate that there are significant differences in survival and mortality risk, but not birth rates, between the two time periods, which suggest improvements in health following the Black Death, despite repeated outbreaks of plague in the centuries after the Black Death.</p></div

D₃₀₊/D₅₊ values and their 95% confidence intervals for the pre- and post-Black Death samples.

<p>D₃₀₊/D₅₊ values and their 95% confidence intervals for the pre- and post-Black Death samples.</p

Kaplan-Meier survivorship functions for the pre- and post-Black Death samples.

<p>Kaplan-Meier survivorship functions for the pre- and post-Black Death samples.</p

Age-at-death distributions for the pre- and post-Black Death samples.

<p>Age-at-death distributions for the pre- and post-Black Death samples.</p

Maximum likelihood estimates (with standard errors) of the Gompertz parameters and the effect of the time period covariate on mortality (with likelihood ratio test).

<p>Maximum likelihood estimates (with standard errors) of the Gompertz parameters and the effect of the time period covariate on mortality (with likelihood ratio test).</p

<em>Yersinia pestis</em>: New Evidence for an Old Infection

<div><p>The successful reconstruction of an ancient bacterial genome from archaeological material presents an important methodological advancement for infectious disease research. The reliability of evolutionary histories inferred by the incorporation of ancient data, however, are highly contingent upon the level of genetic diversity represented in modern genomic sequences that are publicly accessible, and the paucity of available complete genomes restricts the level of phylogenetic resolution that can be obtained. Here we add to our original analysis of the <em>Yersinia pestis</em> strain implicated in the Black Death by consolidating our dataset for 18 modern genomes with single nucleotide polymorphism (SNP) data for an additional 289 strains at over 600 positions. The inclusion of this additional data reveals a cluster of <em>Y. pestis</em> strains that diverge at a time significantly in advance of the Black Death, with divergence dates roughly coincident with the Plague of Justinian (6^th to 8^th century AD). In addition, the analysis reveals further clues regarding potential radiation events that occurred immediately preceding the Black Death, and the legacy it may have left in modern <em>Y. pestis</em> populations. This work reiterates the need for more publicly available complete genomes, both modern and ancient, to achieve an accurate understanding of the history of this bacterium.</p> </div