Flea Circuses topic on QI

Stephen Fry quizzes his contestants on their knowledge of Flea Circuses on the QI quiz show. In a episode called "Flora and Fauna" he is joined by John Sergeant, Jimmy Carr, Jo Brand and Alan Davies.

Q: What was the biggest destroyer of human fleas? Asks Fry
A: Vacuum Cleaners answers John Sergeant.

However Sergeant then goes on to incorrectly comments that if a human being had as powerful legs as a flea that they could jump over the Eiffel tower. The flea can jump 80 times its own height but if you scaled that up to human sizes then it would not be as high. The reason for this is that muscle strength scales with cross section but mass would increase with volume on a cubic scale. This would mean that a human with flea legs could jump (cuberoot of 80)squared i.e. approx 18.5 times their own height. Taking the UK average of 175cm, which multipled by 18.5 is approx 32m which although very impressive is only 1/10 of the height of the Eiffel tower.

I thought Mr Fry was rather over exuberant with regards to the one rare example of the flea band (who were glued to a heated tray) where as the majority of flea performances were about pulling things, something that does not put any more strain on the flea than a horse pulling a cart. It sounded like he got all his information from Wikipedia but the clips from Pathe News were very good.




BBC Flea (contains Adult themes) 5mins -> 9mins