Scientists have discovered the world's oldest blood cells in the remains of a 5,300-year-old iceman found in Italy.
The scientists found traces of blood around an arrow wound that killed the man in the mountains of what is now the Alto-Adige region of northern Italy.
"Otzi the iceman" was discovered in 1991 at 3,200 metres in a glacier by hikers in the German-speaking region near the border with Austria.
His remains were so well preserved that scientists have estimated he was 45-years-old at the time he was killed.
A joint study was conducted at the Centre for Smart Interfaces at Darmstadt Technical University in Germany and the Centre for Nano Sciences in Munich, and published by the Journal of the Royal Society Interface.
The researchers extracted tissue samples from the arrow wound, and from another wound in the iceman's hand.
After using a microscope to identify what appeared to be red blood cells, they confirmed the discovery by using an atomic force microscope which identifies molecules with a laser beam.
The mummified body is kept in the South Tyrol Museum of Archaeology in Bolzano, South Tyrol, Italy.