The Traitors shows how herd mentality tramples on our basic instincts | Martha Gill

More than 9 million people tuned in to the first episode of The Traitors last week .

Last week it overtook Strictly Come Dancing to become the BBC ’s most watched reality show.

The show works because of its deceptively simple setup: a version of the party game Mafia , in which a handful of players are secretly deemed “traitors” and must work to bump off the rest.

In the west, folk theories abound that we are much more autonomous than we are.

The appeal of The Traitors may be that it demonstrates the power of herd behaviour.

But it would be a mistake to imagine these people do not represent the norm.

We evolved not to see things objectively but to survive in groups, which means conforming to them.