Today we have a rare guest Caturday felid; I can’t remember one since I started this site five years ago (has it really been that long?). So here’s Greg’s contribution, which shows a concerto (“Catcerto”) composed by Mindaugas Piecaitis to embellish and complement the playing of Nora the famous piano-playing cat. (The score for “Catcerto” can be found here.)  Greg goes on to relate this to evolution.

by Greg Mayer

Although Jerry posted the following video a couple of years ago, it came to my attention again yesterday, when a friend sent it to me. (And I did not recall until I checked that Jerry had posted it!)

My friend asked, “Can your cat do this?”, to which I replied

“Yes, if you taped her sitting at the keyboard long enough, only selected those bits where she hit several keys in a row, and then had the orchestra play around these selected moments.”

What immediately came to my mind (and what I quickly tried to explain to my correspondent), was that the cat playing the piano was not the result of the cat “knowing” how to play the piano, but rather the result of a cumulative selection process, in which the cat’s more or less random key strokes and rubs are filtered for those that are “good”, and the good ones then strung together.  If you let the cat sit at the piano long enough, recording all the while, then splice together all the times it made several euphonious keystrokes in a row, you can build up a “solo”. The composer then composed a piece around these selected euphonious elements.

The video exhibits something akin to Richards Dawkins’ “me thinks it is like a weasel” story, which he related in The Blind Watchmaker (my favorite of his books, though I’ve not read them all). Given enough time, a monkey pounding at a typewriter would reproduce all of Shakespeare, but it would take a very long time indeed. But if you allow cumulative selection to work—saving correct steps when they occur—it is possible to get a coherent phrase rather quickly. Dawkins illustrated this with a famous line from Hamlet, in which Hamlet is making a fool of Polonius; says Hamlet, “Methinks it is like a weasel.”

The probability of a monkey producing the 28 characters in the sentence in a single try is one in 27 (the number of letters plus the possibility of a space) raised to the 28th power, or roughly 1/10^40– a mind-bogglingly small chance. But if you select any correct letters that happen to appear, and then let incorrect letters vary again, and then repeat, you will soon get the full sentence. In Dawkins’ first try with a simple computer program that implemented this selection algorithm, it took just 43 trials (“generations”) to get it, and that result was typical. The point of course, is that random variation and cumulative selection is a very different process from just random variation (which many critics of natural selection seem not to get).  (The program captures only some of the characteristics of cumulative selection, and Dawkins discusses these caveats in the book: see Chapter 3, “Accumulating small change”).

In the “Catcerto”, the keystrokes of the cat (which are apparently encouraged in some way by her owner, whose hands appear briefly at one point in the tape) are recorded, and the euphonious combinations selected, much as the correct letters are saved in Dawkins’ program. The composer can then select from among these, and splice them together, including changing their order (something for which there is no analogue in Dawkins’ program), and then write the chamber orchestral score around these spliced together euphonious moments.

h/t: D. Pham