14 DAY TRIAL // Now, we know why English people are so arrogant. Because the plague did not touch the cobby ones. At least the mighty hairy not-so-hygienic Anglo-Saxon warriors were much more genetically diverse than today's Englanders.
A new research compared the DNA from ancient and modern English people finding that the country has a smaller genetic diversity than it did one millennium ago. This is different from modern England, regarded as a cultural melting pot, filled with migrants from India and China to Africa and Eastern Europe.
"The findings were unexpected. Modern England is the result of centuries of mixing cultures, and so higher diversity was expected," said lead author Rus Hoelzel, a geneticist from Britain's University of Durham.
Hoelzel's team got DNA samples from the skeletal remains of 48 ancient Britons who lived between 300 and 1000 A.D., which were compared to 6,320 modern samples, focusing on the mitochondrial DNA, transmitted from mothers to their children. Ancient English DNA compared with that coming from thousands of people from various ethnic backgrounds living in present-day England appeared to have been more diverse. Ancient English DNA was also compared with samples coming from people living in continental Europe and the Middle East today and again the ancient DNA won.
"Few of the modern populations were as diverse as our ancient sample," said Hoelzel.
"One possible explanation for this narrowing of diversity might be two major outbreaks of bubonic plague that swept England and much of Europe-the Black Death (1347-1351) and The Great Plague (1665-1666)", said Hoelzel.
The Black Death epidemic could have killed up to 50 % of Europe's population. 300 years later, 20 % of the London's population was wiped out in the Great Plague.
"However, these diseases didn't kill randomly. The plague killed some people while others remained resistant," signaled Hoelzel.
Whole villages of related families were often wiped out, eliminating an entire genetic type in one outbreak.
"If there were only small numbers of people with each DNA type, then the plague could have been enough to make many of these DNA types disappear," said Eske Willerslev, an ancient DNA researcher from the University of Copenhagen. After the epidemics, it seems that England could not recover the loss to the gene diversity, despite the intense immigration into the country over the past 200 years.
"Enough diversity was lost to not be fully compensated by the recent immigration effect," Hoelzel said.
Others have a more critical attitude towards this study.
"Ancient DNA tends to elevate diversity, because the way DNA is damaged over time tends to mimic the mutations that lead to diversity. The way that DNA degrades after a person's death can make ancient DNA appear to have more variation than modern DNA," said Mark Thomas, a geneticist at University College London.
"DNA damage, an artifact of the data, is the other obvious explanation for this decrease in diversity." agreed Willerslev. "We undertook multiple controls to ensure that DNA contamination and post-mortem change could not explain the change in diversity," countered Hoelzel.
"I also doubt that the Black Death and the Great Plague would have caused enough reduction in population to explain the drop in diversity. The population reduction would have had to be extreme in absolute, rather than relative, numbers to cause the loss of diversity claimed," said Thomas.
English arrogance...