Young black bears in California have now been showing uncharacteristic signs of friendliness towards humans, and wildlife experts fear that a brain disorder may be the cause of this ‘dog-like’ behaviour. The phenomenon has been noticed since around 2014; videos have appeared on social media showing strange encounters in the state and neighbouring Nevada. In one clip, a black bear cub approaches a snowboarder at the Northstar ski resort and steps onto the board; in another, a dazed-looking bear wanders into a residential back yard and sits in the porch munching apples fed to it by curios onlookers. In still another, a bear walks into a classroom and sits down at the back.

Other symptoms include tremors and a tilted head (an endearing behaviour any dog lover appreciates!). Unlike grizzlies, which have a fierce reputation, black bears tend to be timid and avoid people. Scientists who conducted a post-mortem on one euthanised cub say it was suffering from encephalitis, a brain inflammation usually caused by a viral infection. Vets have identified five new viruses while examining the affected bears, but have yet to identify a direct link to the erratic behaviour.

This type of synurbic behaviour is now common amongst polar bears which are increasingly forced, due to loss of habitat, to live alongside humans in urban environments in order to get food by scavenging. In the UK this behaviour is evidenced amongst foxes and the common pigeon as examples. Indeed, it is thought that this is how dogs became domesticated originally, with estimates varying from between 12,000 and 40,000 years ago or more.