Image: Cemetery
Museum of London Archaeology
Six skeletons are lined up in a grave at the Eath Smithfield cemetery excavation, conducted by Museum of London Archaeology. Material from the teeth of those buried in the cemetery was analyzed to produce the genome for the bacterium that caused the Black Death.
By
updated 10/12/2011 2:04:11 PM ET 2011-10-12T18:04:11

Scientists have cracked the genetic code of the Black Death, one of history's worst plagues, and found that its modern-day bacterial descendants haven't changed much over 600 years.

Luckily, we have.

The evolution of society and medicine — and our own bodies — has far outpaced the evolution of that deadly bacterium, scientists said.

  1. Science news from NBCNews.com
    1. NOAA
      Cosmic rays may spark Earth's lightning

      All lightning on Earth may have its roots in space, new research suggests.

    2. How our brains can track a 100 mph pitch
    3. Moth found to have ultrasonic hearing
    4. Quantum network could secure Internet

The 14th-century bug Yersinia pestis is nearly identical to the modern-day version of the same germ. There are only a few dozen changes among the more than 4 million building blocks of DNA, according to a study published online Wednesday in the journal Nature.

What that shows is that the Black Death, or plague, was deadly for reasons beyond its DNA, study authors said. It had to do with the circumstances of the world back then.

In its day, the disease killed between 30 million and 50 million people — about 1 of every 3 Europeans. It came at the worst possible time — when the climate was suddenly getting colder, the world was in the midst of a long war and horrible famine, and people were moving into closer quarters where the disease could infect them and spread easily, scientists say. And it was likely the first time this particular disease had struck humans, attacking people without any innate protection.

"It was literally like the four horseman of the apocalypse that rained on Europe," said study lead author Johannes Krause of the University of Tubingen in Germany. "People literally thought it was the end of the world."

Evolution at work
In devastating the population, it changed the human immune system, basically wiping out people who couldn't deal with the disease and leaving the stronger to survive, said study co-author Hendrik Poinar of McMaster University in Ontario.

But simple antibiotics today, such as tetracycline, can beat the bacteria, which doesn't seem to have properties that enable other germs to become drug-resistant, Poinar said. Plus, changes in medical treatment of the sick, coupled with improved sanitation and economics, put humanity in a far better position. And there's an immune system protection we mostly have now, Poinar said.

"I think we're in a good state," Poinar said. "The reason we do so well is that conditions are so different."

People still get the disease, usually from fleas from rodents or other animals, but not that often. There are around 2,000 cases a year in the world, mostly in rural areas, with a handful of them popping up in remote parts of the United States, according to the Centers for Disease Control and Prevention. Earlier this year, two people in New Mexico were diagnosed with plague. In 1992, a Colorado veterinarian died from a more recent strain, one that scientists used heavily in their study.

Drilling into skeletons
To get the original Black Death DNA, scientists played dentist to dozens of skeletons.

During the epidemic in the 14th century, about 2,500 London area victims of the disease were buried in a special cemetery near the Tower of London. It was excavated in the mid-1980s with 600 individual skeletons moved to the Museum of London, said study co-author Kirsten Bos, also of McMaster University. She removed 40 of those teeth, drilled into the pulp inside the teeth and got "this dark black powdery-type material" which likely was dried blood that included DNA from the bacteria.

And when she was done, Bos returned the teeth, minus a little DNA, to the skeletons at the museum.

When the same scientists first tried mapping the bacteria's genetic makeup, it appeared to be a distinctly different germ than what is around currently. But part of that was a reflection of working with 660-year-old DNA. Newer, more refined techniques revealed less difference between the early-day and modern Y. pestis bacteria than between a mother and daughter, Krause said.

That's a surprising result, but the work was well done and makes sense, said Julian Parkhill, a disease genome expert at the Wellcome Trust Sanger Institute in Britain. Parkhill was not involved in the research but has studied the bacteria.

"Getting an effectively complete genome sequence of a bacterium that lived nearly 700 years ago is incredibly exciting," Parkhill said.

Copyright 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Explainer: 7 ghoulish archaeological discoveries

  • University of Bradford

    Remember the haunted house in grade school where your hand was guided into a bowlful of "brains"? Those skinned grapes have nothing on what happened to Rachel Cubitt of the York Archaeological Trust in England. As she was cleaning a 2,000-year-old skull unearthed during a campus expansion project into a prehistoric farm, she "felt something move inside the cranium. Peering through the base of the skull, she spotted an unusual yellow substance," read a press release announcing the discovery of the oldest surviving human brain in Britain. The skull was found alone in a muddy pit. Researchers believe it may have been a ritual offering. In this image, Cubitt is using an endoscope to examine the remains. Click the "Next" arrow above to learn about six more ghoulish archaeological discoveries.

  • Bricks thwarted vampires

    Matteo Borrini  /  AP

    A wooden stake in the heart is one well-known way to thwart a vampire, but the method was insufficient in the 16th century. Back then, a sure-fire vampire slaying entailed putting a stone or brick in the suspected vampire's mouth so that it would starve to death. The remains of the 60-year-old woman found in a mass grave near Venice, shown here, was one of those purported vampires, according to Matteo Borrini, a forensic archaeologist and anthropologist at Florence University. At the time, plague ravaged the region. People were buried in mass graves that were often reopened to add new bodies. When they did, bloated bodies with blood spilling from their mouths and holes in their head shrouds were often revealed. These corpses were thought to be vampires.

  • Ball and chain tied to gruesome tale

    Museum of London

    A 17th century iron ball and chain pulled from thick, black mud on the banks of the River Thames in London may have a gruesome tale to tell, according to scientists. The 18-pound shackles were found with the lock fastened and no key, suggesting the prisoner either slipped out of custody or drowned while attempting to escape. Kate Sumnall, an archaeologist with the Museum of London, shown here, told reporters the iron is of high quality and was unlikely discarded on purpose.

  • Unearthed Greek vessels contain human remains

    AP

    Human remains found in one of two large, silver vessels in the heart of Aigai, the ancient capital of Macedonia, have thickened a murder-mystery plot. The unidentified remains, thought to date to the end of the 4th century B.C., were unearthed a few steps away from what some archaeologists speculate are the bones of Alexander the Great's murdered teenage son. What's odd is both burials are outside nearby cemeteries, suggesting either a form of punishment or an illegal act, archaeologists told the Associated Press. "Either way, it was an exceptional event," archaeologist Stella Drougou of Aristotle University, told the news service. "And we know the history of the Macedonian kings is full of acts of revenge and violent succession."

  • Urine-filled 'witch bottle'

    For those afraid a witch may have cast a spell upon them, follow this recipe: pee in a bottle, toss in some fingernail clippings, strands of hair, iron nails, brass pins and a heart-shaped piece of leather pierced with a bent nail and then bury it upside down. If all goes well, the trick will cast the spell back on the witch, perhaps killing her — or so goes a 17th century witchcraft belief. Such a bottle was discovered in Greenwich, England, and dates to a time when witchcraft beliefs were more common, according to British Archaeology magazine.

  • Bog body preserves tale of violent death

    Trustees of the British Museum

    Someone in the first century had it out for Lindow Man, a 25-year-old found face down in a northwest England moss bog. Examination of the well-preserved body shows that the otherwise healthy gentleman suffered two blows to the head and a swift knee to the back. A cord tied around his neck was likely used to strangle him and break his neck. Then, just to make sure he was dead, his throat was slit. The sequence of events, some scientists suggest, is consistent with a ritualistic killing, perhaps a human sacrifice carried out by Druids.

  • Gory sacrifice found at Teotihuacan

    Henry Romero / Reuters

    In 2004, a grisly scene was unearthed outside of modern-day Mexico City. Decapitated bodies were found tossed to the side of a burial tomb, their hands tied behind their backs. The discovery suggests the little-known culture that built the giant Pyramid of the Moon at Teotihuacan held bloody, sacrificial rituals. Two other bodies decorated with beads and greenstones, as well as animals and other offerings, were also found in the tomb. "Whether the victims and animals were killed at the site or a nearby place, the foundation ritual must have been one of the most terrifying acts recorded archaeologically in Mesoamerica," archaeologist Saburo Sugiyama of Aichi Prefectural University in Japan said in a statement announcing the discovery.

Discuss:

Discussion comments

,

Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments