Scientists have identified the oldest known case of rickets - a young vegetarian woman who lived in the Hebrides during the Neolithic period, around 4000 to 2,500 BCE.

Rickets is a disease caused by a lack of vitamin D and calcium, which results in bone malformations and fractures. It became common during the industrial revolution, as urban populations working in factories with no natural light, and ate a poor diet, so the scientists were surprised to find the disease in a woman who lived in the countryside. In their announcement of the findings to the British Science Festival on Wednesday, they suggested a possible explanation.

"My suspicion with this woman is that she was probably ill for a long time, and was kept inside", Professor Ian Armit from the team at the University of Bradford told the Festival. From the formation of the bones, the team think the woman contracted rickets in childhood, and survived to adulthood.

The body was one of many found in 1912 on the island of Tiree by antiquerian Mungo Buchanan. But the islanders were so angry at the excavation of the site, they chased the archaeologists off the island and re-buried the other bodies found at the site. The woman's body was the only one taken back to the Hunterian Museum in Glasgow.

The scientists analysing it using modern techniques to understand more about her lifestyle, as they think her diet may have been another reason she developed rickets was her diet. They worked out what she ate by crushing up the teeth, and using isotope analysis to work out the different levels of molecules like carbon and nitrogen. from these, they think that the woman went through periods of famine, and ate an exclusively vegetarian diet, avoiding the food source of fish in the nearby North Sea.

"There was no native animals [in the Hebrides], no fish in the rivers, so there's nothing other than the sea if the crops fail", said Dr Janet Montgomery from the Univeristy of Durham. She said that avoiding fish is a trend in all the bodies they have found from the late Neolithic. To avoid such a good source of food even in times of starvation, they think Neolithic people must have had a real cultural taboo around eating fish.