(South Tyrolean Museum of Archaeology)
Scientists studying a prehistoric mummy have discovered the world’s oldest blood cells
Scientists think Otzi may have looked something like this. (Reconstruction by Kennis © South Tyrol Museum of Archaeology, Augustin Ochsenreiter)
Scientists announced earlier this month that they have discovered the oldest traces of human blood ever identified. The Italian and German scientists found the blood while examining a 5,300-year-old mummy that had been found frozen in a glacier in the Alps mountain range in Europe in 1991. A mummy is a body that has been preserved after death.
Otzi, as the mummy has been named, was about 45 years old when he was killed by an arrow wound to the shoulder. The arrow sliced an artery, which carries blood from the heart to the rest of the body. When the scientists looked under a microscope at tissue samples from that wound and from another on Otzi’s hand, they saw what looked like red blood cells.
The scientists then examined the tissue with a special microscope called an atomic force microscope. It uses a tiny probe to scan the surface of tissue and create a three-dimensional image of it. The image showed red blood cells with the same doughnut shape found in healthy people today.
To be certain that the particles were not pollen or bacteria, the scientists used another research method. Raman spectroscopy lights up tissue with a laser beam. By analyzing the patterns of the light scattered by the laser, the scientists saw that the objects were, without a doubt, red blood cells.
“Up to now, there had been uncertainty about how long blood could survive,” says study leader Albert Zink, head of the Institute for Mummies and the Iceman at Italy’s European Academy of Bozen/Bolzano.
A REVEALING FIND
The discovery of the blood answered long-standing questions about Otzi’s death. The blood cells contained fibrin, a protein involved in the clotting of blood. It is present in fresh wounds but disappears rapidly. The fibrin shows that Otzi died very quickly after being hit by the arrow.
What scientists have learned about Otzi may help forensic scientists, people who analyze evidence from crime scenes. The new methods used to examine Otzi’s blood may help determine the age of blood spots left after a violent crime—something forensic scientists have not been able to do so far.
Scientists have been studying Otzi for more than 20 years. Even though he lived thousands of years ago, researchers have been able to find out remarkable details about him. For example, they know that he had brown eyes and brown hair. He ate wheat and barley and was allergic to milk.