Do bulls attack red rags?

The saying "Red rag to a bull" has become so commonplace that everyone is sure it must be rooted in fact. It's used to describe an action which is likely to aggravate, or make an inflamed situation worse.

The assumption is that the origin lies with the angry reaction a bull inherently exhibits when it sees the color red, and this is further reinforced with the use of red flags by matadors in bullfights.

Is there any basis in this? It turns out not to be the case. In fact bulls show no special behaviour to any particular color, and the gruesome reason those flags are red is in fact to try to mask the blood which results from the bull's torment.

Myth busted

Livescience has the lowdown. It's even more ridiculous a myth when you realise a bull is in fact color blind. The popular TV show Mythbusters placed various colored flags and dummies around a bull, and showed what science was saying all along - it's not the color, but the movement which the bull charges at. It's also widely assumed the phrase originated in bull-fighting, but this isn't the case either. The idea of waving a red rag started out as just meaning to talk, i.e. the rag was the tongue itself. it's in print as uch from as early as 1605. The earliest mention of waving a red rag to alert, or provoke something was actually to pheasants, where they would have taken flight from their undergrowth in order to be more easliy shot or captured when exposed. The practice was used for various other creatures, such as turkeys or vipers, and it wasn't referred to as being able to deliberately provoke bulls until 1873.

Whilst it's not true in the real world, the phrase is useful as a metaphor in language, so continues to be used.