The allegation of the overwhelming strength of chimpanzees and that they are five times stronger than humans was derived from the biologist John Bauman who experimented with them in the year 1926.
In his experiment, chimpanzees and humans had to pull on a dynamometer. The humans were all football players and managed a maximum of 220 kilos in comparison to the strongest chimpanzee that pulled 572 kilos.
The football players were allowed to use the dynamometer as it suited them, whereas the chimpanzees had to pull on a rope which was conducted through the bars of their cage. The researcher rounded the ratio generously and noted that the ‚factor five‘ is quite plausible!
His findings were published in several books and has since spread worldwide, even prevailing through elaborate contradiction that were made by researchers in the forties that found full-grown chimps to be as strong as a grown man.
However if you compare the strength to body weight ratio, then chimpanzees are about twice as strong as humans. Why is it like this? There are two possible reasons: Firstly; The major muscles of a chimpanzee are longer therefore twice as effective. Secondly; Humans have to pay the price for their highly developed brain: We are able to move our muscles very graciously whereas chimpanzees on the other hand always execute their full strength.