A later analysis suggested the sequence may have been a different "Borrelia" species. A 2012 paper by paleoanthropologist John Hawks suggests that Ötzi had a higher degree of Neanderthal ancestry than modern Europeans. In October 2013, it was reported that 19 modern Tyrolean men were descendants of Ötzi or of a close relative of Ötzi. Scientists from the Institute of Legal Medicine at Innsbruck Medical University had analysed the DNA of over 3,700 Tyrolean male blood donors and found 19 who shared a particular genetic mutation with the 5,300-year-old man. In May 2012, scientists announced the discovery that Ötzi still had intact blood cells. These are the oldest complete human blood cells ever identified. In most bodies this old, the blood cells are either shrunken or mere remnants, but Ötzi's have the same dimensions as living red blood cells and resembled a modern-day sample. In 2016, researchers reported on a study from the extraction of twelve samples from the gastrointestinal tract of Ötzi to analyze the origins of the "Helicobacter pylori" in his gut. The "H. pylori" strain found in his gastrointestinal tract was, surprisingly, the hpAsia2 strain, a strain today found primarily in South Asian and Central Asian populations, with extremely rare occurrences in modern European populations. The strain found in Ötzi's gut is most similar to three modern individuals from Northern India; the strain itself is, of course, older than the modern Northern Indian strain. The cause of death remained uncertain until 10 years after the discovery of the body. It was initially believed that Ötzi died from exposure during a winter storm. Later it was speculated that Ötzi might have been a victim of a ritual sacrifice, perhaps for being a chieftain. This explanation was inspired by theories previously advanced for the first millennium BCE bodies recovered from peat bogs such as the Tollund Man and the Lindow Man. In 2001, X-rays and a CT scan revealed that Ötzi had an arrowhead lodged in his left shoulder when he died and a matching small tear on his coat. The discovery of the arrowhead prompted researchers to theorize Ötzi died of blood loss from the wound, which would probably have been fatal even if modern medical techniques had been available. Further research found that the arrow's shaft had been removed before death, and close examination of the body found bruises and cuts to the hands, wrists and chest and cerebral trauma indicative of a blow to the head.