ROME - Scientists examining the remains of "Otzi," Italy's prehistoric iceman who roamed the Alps some 5,300 years ago, said on Wednesday they have isolated what are believed to be the oldest traces of human blood ever found.
The German and Italian scientists said they used an atomic force microscope to examine tissue sections from a wound caused by an arrow that killed the Copper Age man, who was found frozen in a glacier, and from a laceration on his right hand.
"They really looked similar to modern-day blood samples," said Professor Albert Zink, 46, the German head of the Institute for Mummies and the Iceman at the European Academy in Bolzano, the capital of Italy's German-speaking Alto-Adige region.
"So far, this is the clearest evidence of the oldest blood cells," he said by telephone, adding that the new technique might now be used to examine mummies from Egypt.
The studies were carried out in conjunction with the Center for Smart Interfaces at Darmstadt Technical University in Germany and the Center for Nano Sciences in Munich.
Over the last two decades, scientists have collected data from the stomach, bowels and teeth of the well-preserved man, who was found protruding out of a glacier by German climbers in 1991 in the Tyrolean Alps on the Austrian-Italian border.
Otzi, whose nickname derives from the German word for the area where he was found, had brown hair and type-O blood and was believed to be 45 when he was felled by an arrow while climbing the high mountains some 5,300 years ago.
The nanotechnology instrument used by Zink and his team scans the surface of the tissue sections using a very fine probe, the scientists said in a summary of their report.
As the probe moves over the surface, sensors measure every tiny deflection of the probe, line by line and point by point, building up a three-dimensional image.
Zink, an anthropologist, said the red blood cells his team found had a classic doughnut shape seen in healthy people today.
"It is very interesting to see that the red blood cells can last for such a long time," he said.
"This will also open up possibilities for forensic science and may help lead to a more precise determination of the age of blood spots in crime investigations," he added.
Earlier this year, the scientists made the first complete genome-sequencing on Otzi, determining that the man had a predisposition for cardiovascular diseases and brown eyes that betrayed possible near-Eastern origins.
Otzi had lactose intolerance that was common among Neolithic agrarian societies and was also the first-known carrier of Lyme disease, a bacterial infection spread by ticks.
Examination of the wound where the arrow entered Otzi's back identified fibrin, a protein involved in the clotting of blood, a summary of the report said.
Because fibrin is present in fresh wounds and then decays, this appears to show that the hunter died quickly rather than after a few days as had been previously thought, it said.
Zink carried out his research with Marek Janko and Robert Stark, professors of material sciences at the Center for Nano Sciences in Munich and Italian colleagues in Bolzano.
To be certain that the specimens they were examining were blood and not pollen, the scientists used a second analytical method known as the Raman spectroscopy method.
In that method, a laser beam illuminates a tissue sample and analysis of the spectrum of the scattered light permits the identification of various molecules.
Zink said he and his colleagues hope to carry out further analysis on Otzi's enzymes, proteins and immune system.
"We hope we can make good progress in this area too," he said.
The complete results will be published by Britain's Journal of the Royal Society Interface.