It is just a hypothesis which is based on the fact that archaeologist have founded some damaged fraction of dead bodies dating back to 11th and 14th centuries C.E. in Wharram Percy, which is an abandoned 14th century village in Yorkshire. There are visible evidence of extensive mutilation of those bodies.
Wharram Percy was a town where people mostly do farming for their living. The researchers found 137 bones which seem substantial remains of some 10 individuals. These 10 bodies were of both sexes, male and female while their age could range from 2 years to more than 50 years.
After death, the dead bodies were not only damaged but also burned. This raises the question that why did they do like this to their ancestors.The evidences can be interpreted in many ways like they did this to stop the dead to rise and harm them or could be a case where these individual had punished for some act which was highly unacceptable to their society.
Prevention from zombies is not the only theory available in history to explain the Mutilation of dead bodies, it had occurred in many societies with many reasons. But, with Wharram Percy, this is the only possible theory suitable to explain as all other available theories have been ruled out with some concrete facts.
First theory that came into mind with this damaged body is that they may belong to some other group of starngers who have got punished by those inhabitants of Wharram Percy but genetic and ecological findings suggests that they have grown up on that location itself they have not migrated from some alien location. These findings ruled out this theory of them being foreigners.
Second theory that comes into mind is cannibalism but cut marks on the bones could be found near neck and head area not near area of muscles, which indicates that these bodies were not used for food.