Perfide! Spilled blood is not, as alleged, that of Louis XVI

In its latest contribution to historical anthropology, genetic sequencing has shown that a lavishly decorated gourd said to contain the blood of the French King Louis XVI does not, very likely, bear the DNA of France’s final monarch.

Helas! Can no one -- not even the ancient purveyors of gruesome relics, amulets and royal remains -- be trusted? Apparently not, as historians, aided by the burgeoning science of genetic analysis, are learning.

Louis XVI’s death, after an 18-year reign and a fateful flight from French revolutionaries, came by guillotine on Jan. 21, 1793, and brought an end to more than 1,000 years of French monarchy. In the Place de la Revolution in Paris, members of the crowd surged forward bearing rags and handkerchiefs to capture the kingly blood as it gushed from his freshly-beheaded body.

Among the crowd of grisly souvenir-collectors was one Maximilien Bourdaloue, whose prize, according to text burned into the richly decorated surface of the gourd, was contained within. The gourd’s surface was otherwise covered with decoration praising the heroes and principles of the French Revolution.

But the DNA contained in Bourdaloue’s blood-soaked handkerchief did not, apparently, issue from the carotid artery of Louis XVI, a group of researchers from Spain, France and UCLA has concluded.

The DNA encased in the famous gourd, the researchers say, appears to have belonged to a man not as tall as Louis XVI, who was often described as “the tallest man in court.” And the source of the preserved blood probably had brown eyes -- not the blue eyes so frequently captured in portraits of the elegant king and described in the letters of his wife, Marie-Antoinette.

Their report was published this week in the journal Scientific Reports.

In its use of the most sophisticated and comprehensive methods of genomic analysis, the study reflects a new era for forensic anthropology and suggests that future debates over historical facts are more likely to be answered in a lab than in a library.

That finding overturns and confirms two sets of conclusions drawn earlier by genetic analyses of a cruder sort. Both of those compared the Y chromosome of the DNA in the gourd with that of descendants of the House of Bourbon. One found links that suggested the blood was indeed that of Louis XVI. But a later Y chromosome comparison, which used the blood of Bourbon descendants from different branches of the formerly royal family, revealed the blood could not have been that of the king.

Mysterieux, to say the least.

Though widely used in genealogical research, paternity testing and forensics, the Y chromosome’s pattern of repeated DNA letters is not as definitive a test of genetic relatedness as are the patterns found on other chromosomes. In the latest study, researchers conducted an analysis of the full genome, taking snippets of DNA at regular but widely interspersed intervals.

Then they conducted a more intensive analysis, sampling genetic code at closer intervals, of the exome, the 2% of the human genome that codes for proteins but which contains roughly 85% of the single-nucleotide polymorphisms (or SNPs) known to cause disease in humans.

The researchers also took pains to filter the human genetic material from that of bacteria and fungi that have shared space in the gourd for decades and possibly centuries. And, they compared the gourd blood’s Y chromosomes with several samples of populations from throughout Europe.

What they found was that the person whose blood was contained in the gourd was likely to have been the descendant of people from Northern Italy -- not the known ancestry of Louis XVI. The SNPs examined by the researchers don’t suggest a man of Louis XVI’s purported stature, nor of his apparent girth (Marie-Antoinette described the king as chubby in her correspondence). And the researchers assessed the likelihood that the blood came from a man with blue eyes -- as Louis XVI had -- at only 2.4%.

On the basis of genetic data alone, the researchers modestly acknowledged, they could not “totally discard that the gourd’s sample belongs to Louis XVI.” They have saved their analysis, in case other relics purported to come from relations of Louis are discovered.