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Extracting Mummy DNA

  • Teacher Resource
  • Posted 06.28.12
  • NOVA

This video segment adapted from NOVA: "Iceman Murder Mystery" describes the process of testing the DNA of a mummy called Ötzi who died over 5,000 years ago in the European Alps. Getting DNA samples from human remains that are this old is very difficult; however, when DNA can be tested, it can give us very detailed information on how humans lived, what they ate, what illnesses they suffered, and, as seen in the video, even whether they were lactose intolerant.

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NOVA Extracting Mummy DNA
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  • Media Type: Video
  • Running Time: 3m 37s
  • Size: 13.2 MB
  • Level: Grades 6-12

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Source: NOVA: "Iceman Murder Mystery"

This media asset was adapted from NOVA: "Iceman Murder Mystery."

Teaching Tips

Here are some of the main ideas students should take away from this video:

  • The technology used to get DNA samples from a mummy as old as Ötzi has only been developed very recently.
  • DNA can tell scientists about an ancient human’s eye color, medical history, and genetic mutation (such as lactose tolerance).
  • Bone samples are broken apart and processed to separate out DNA for analysis.
  • Ötzi’s DNA sample shows that he was lactose intolerant: he could not digest cow’s milk.
  • No ancient humans could digest cow’s milk—that ability is a genetic mutation that only 40 percent of adults today possess.

Questions for Discussion

    • What made it less likely that DNA samples could be taken from Ötzi? What made it more likely that they could?
    • Why do you think modern humans need to develop a tolerance to lactose?
    • Why do you think the Alps, where Ötzi lived, currently have the highest percentage of people who can digest cow’s milk?

Transcript

NARRATOR: Techniques of salvaging and sequencing DNA have only recently improved enough to make it possible to get useful information from a mummy as old as Ötzi. But it will still be extremely difficult.

ALBERT ZINK (Director, Institute for Mummies and the Iceman): Testing the DNA of the Iceman is difficult, on one hand, because he's a wet mummy, and wet mummies have a lot of humidity. This is very bad for the DNA preservation. On the other hand, he was frozen for more than 5,000 years, and this turned out to be good, because the coldness preserves the DNA.

NARRATOR: If fragments of DNA can be reconstructed, scientists have hopes they will be able to learn a great deal about characteristics like his eye color, medical history and genetic mutations. But first they have to get the DNA They will follow a multi-step process, in order to see if it is even possible.

For Angela Graefen, a researcher at Albert Zink's lab, helping to piece together the Iceman's genetic profile is the chance of a lifetime.

ANGELA GRAEFEN (Researcher, Institute for Mummies and the Iceman): I've always been very interested in mummies, and when I got the chance to work on the Iceman, yeah, well, of course I…it's everybody's dream to work on such a, such a well-known sample as that.

NARRATOR: First, Graefen cuts the precious sample of Ötzi's bone into smaller pieces using a diamond-tipped saw. Tiny bone samples are placed into a sterile container with a steel ball. When the container is shaken at a high speed, the ball pulverizes the bone, breaking apart individual cells. Graefen adds various chemicals to make the DNA easier to extract. Days later, what's left is a mixture of clear water and a golden-hued pure DNA.

NARRATOR: Ötzi's genes indicate he was lactose intolerant; he couldn't digest milk as an adult. It's a condition many believe to be a result of an ailment or allergy. But they're wrong.

ANGELA GRAEFEN: Many people think lactose intolerance is an illness, but it's, you have to bear in mind, it's not, actually. It's the original state of humans. In the Stone Age, all humans were lactose intolerant.

NARRATOR: In the ancient past, all humans could digest milk as babies, but lost the ability as they grew older. That’s exactly what happened to Ötzi. But around the time when Ötzi lived, a genetic mutation occurred that allowed some adults to digest milk. The mutation spread, its survival probably favored by the greater availability of domesticated cow's milk. Today, about 40 percent of adults worldwide are able to digest milk. But in the Alps, where Ötzi lived, 85 percent can digest dairy products.

Resource Produced by:


					WGBH Educational Foundation

Collection Developed by:


						WGBH Educational Foundation

Collection Credits



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