Monkey’s uncle

This expression is frequently in the form of an exclamation of surprise 'Well I'll be a monkey's uncle!' or incredulity 'If you believe that, then I’m a monkey’s uncle!.' A case has been made that it derives from Darwin's Origin of Species, which was published in 1868, but the debate about our evolution from apes was going on before Darwin published his book. The Oxford English Dictionary, however, dates the expression from 1925, but instances have been found from the mid-19th century, which adds credence to the Origin of Species connection. See also Not give a monkey's