Q From Michael Josett; Chuck Emery: I’ve always been curious where monkey’s uncle came from and what it means.
A What it means is nothing very profound. It’s just an exclamation of surprise: “Well, I’ll be a monkey’s uncle!”
It is thought to have been a reference to Darwin’s Origin of Species of 1859, in which he argued the close relationship between humans, apes and monkeys. You may recall the famous debate between “Soapy Sam” Wilberforce, the Bishop of Oxford, and Thomas Huxley, in which the bishop is said to have asked sarcastically whether “it was through Huxley’s grandfather or grandmother that Huxley claimed his descent from a monkey.”
Most reference books suggest the expression dates from the 1920s, but I found this parody of Longfellow’s Song of Hiawatha in James Parton’s compendium The Humorous Poetry of the English Language. It’s said to be from Punch but is undated; however, it must have appeared in that magazine before 1881, when the book came out:
Out came sundry comic Indians
Of the tribe of Kut-an-hack-um.
With the growling Downy Beaver,
With the valiant Monkey’s Uncle.