Scientists from McMaster University, the University of Sydney, and the University of Melbourne have conducted the biggest investigation of its type by carefully comparing hundreds of current and ancient genome sequences in an effort to learn more about the origins and spread of bubonic plague in both ancient and modern times.
The genesis, evolution, and spread of the plague remain elusive mysteries, despite significant developments in DNA technology and research.
The plague caused the two worst pandemics in recorded history. Nonetheless, scientists have been unable to explain the ebb and flow of species, or why some die out while others endure for years.
In a new report published today in Communications Biology, researchers from McMaster employ extensive data and analysis to outline what is known so far about the complicated history of Y. pestis, the bacterium responsible for the plague.
In the study, researchers analyzed over 600 genome sequences from all over the world to better understand the progression of the plague from its first appearance in humans over 5,000 years ago through the plague of Justinian, the medieval Black Death, and the current (or third) Pandemic, which emerged in the early 20th century.
The scientists investigated genomes from strains found all across the globe and of varying ages, and they found that Y. pestis had an unstable molecular clock. This complicates the task of measuring the rate of mutation accumulation in its genome over time, which is necessary for establishing emergence dates.
Since Y. pestis develops so slowly, pinpointing its point of origin is almost difficult.
The infection has been transported throughout the world by humans and rats via travel and commerce at a rate that exceeds the rate at which its DNA has developed. For instance, tracing the source of a pandemic is very difficult since similar genetic sequences have been discovered in countries as far apart in time as Russia, Spain, England, Italy, and Turkey.
Expertly crafted a novel approach for discriminating between several populations of Y. pestis, which allowed them to identify and date five populations across history. This included the most well-known ancient pandemic lineages, which researchers now believe formed decades or perhaps centuries before the pandemic was historically reported in Europe.