Two of the initial cases have used monkeys in their research but have not suffered recent bites.

Some scientists say privately that they would rather use monkeys than chimpanzees, for example, because chimpanzees seem more human.

The company was using monkeys there to test cosmetics and drugs, according to The Washington Post.

They make their living by fortune telling, snake charming and using monkeys and dogs in performances.

Although it has been successfully performed using dogs, monkeys and rats, no human is known to have undergone the procedure.

A number of countries have used monkeys as part of their space exploration programmes, including the United States and France.

This study controls for external societal influence by using monkeys as the subject, and projects results to humans, the closest animal relative.

"We used monkeys, about 200 to 300 each year," Lepyoshkin later recounts.

However, it is a very sensitive issue, in particular when it comes to research using monkeys and especially great apes.

A curling minigame uses monkeys instead of the traditional curling stones.