Women labelled as "witches" by their rivals in rural China are more likely to socialise, trade, and form relationships with members of other witch's families, according to a new study.

While belief in witchcraft has sensibly declined around the world with improvements in education, some communities are still suspicious of alleged witches and their supernatural powers.

In rural China, such persons - mostly adult women - are called "zhu." The negative label, often linked with poisoning food or water and other supernatural abilities, is used to cast aside some families to the benefit of others.

British and Chinese anthropologists and scientists analysed the social organisation of five villages – 800 households – of the Sichuan Province for three years. They looked at how the communities lived, worked and traded together.

They specifically looked into how being labelled as "witches" influenced some families' status and social circles within the community. Their findings were published in Nature.

They realised that not only were "zhu" families excluded by the rest of the villages, they themselves only socialised with other people labelled as "zhu." In gift exchanges prompted by the scientists, zhu would not give nor receive any presents with non-zhu families.

The research team also noted differences on who would help whom when it came to farm work. The society remained highly secluded between zhu households and non-zhus.

Such a divide was also present in how people picked their sexual partners: zhu women would find their partners in the zhu subcommunity and evolve in a small zhu-only network. Similarly, non-zhu people would remain with non-zhu people. It's extremely rare that any zhu would get together with a non-zhu.

Being called zhu affected women more than men, as women are considered the head of the households in the province. In particular, zhu women struggled with fertility more than non-zhus, while males didn't experience any fitness costs. Women would gradually become more and more excluded from the rest of the community as they aged, because older zhus are considered more dangerous.

However, the study reveals that the exclusion didn't only have negative aspects. Zhu families mostly tended to be slightly wealthier than the rest of the community.

The origins of the zhu label are mostly unknown, and members of the community couldn't remember why some families were branded as witches, even the families themselves. Traditionally, women would be called witches based on their physical attributes – if they were particularly beautiful, for instance.

The research team suggests that rivalry prompted some families to accuse others of being witches – because of their beauty or their wealth. Accusing someone of witchcraft was a way of getting rid of the competition, as rivals would then be excluded by the rest of the community. The fact families stayed in the village for many generations – around 82% of the villagers in the study had never left their own town – explains why the stigma was passed on through generations. The locals' fear that the tag could be contagious also explains why the belief is so deeply-rooted within the community as well.

The study also indicates that while excluded, witches in a community are tolerated for specific reasons, mainly that their suspected powers could be useful in times of conflict against outsiders and locals will go to them to defend the community against enemies.

Finally, not all members of the village believed in witchcraft. However, while they didn't believe some of their fellow villagers were witches, they would exclude them nonetheless.

They would do that in order to avoid being "contaminated" by association and ending up being excluded as well. According to the research team, this is why such a belief was allowed to persist into the 21st century: those who don't punish would be punished themselves, so as long as there will be people to exclude them, there will be witches in the Sichuan Province of China.