What really obvious thing have you only just realised?

stefan idiot jones wrote: »

I've just realised that I have never seen or heard of anyone slipping on a banana skin.

(TV and cartoons aside)

The early comedy cinema joke of slipping on a banana peel was a reference to slipping in horse manure. During the early days when cinema was considered an art form and they were worried that showing manure would cheapen the art, so they used a banana peel instead.

...
The horses of New York City killed 20,000 people in 1900 because of their manure. While it was used as a fertiliser, they were so many horses in the city that there was too much manure (2.5 million tonnes a day) and so it helped to spread diseases like typhus, typhoid and cholera. Horses were used in transportation; pulling most vehicles (London had 50,000 of them just in the public transport system). In New York, 41 horses died a day. The people preferred to leave the bodies to putrefy because the bodies were easier to carve up. Apart from fertiliser, horse manure can be ground into a powder which can be used for moulds. Astronomer William Hershel used such a mould to make one of his telescope mirrors or "speculum". Other than manure, the horses themselves were dangerous because they can bolt, drag people off with them, trample people, and make a lot of noise. Interestingly, the thing which helped stop this environmental disaster was cars, because they made traffic safer, quieter and faster. Having horses in a city is seven times more dangerous than cars. While people say that traffic today is at the same speed as the horse, it should be pointed out that there is a lot more traffic.