The Coolidge Effect

Editors’ Note:  we welcome our second guest blogger, Jason.

It’s mating month for the sheep, and Lori and I spent much of the holiday weekend trying to watch sheep get their swerve on.*  Neither we nor Calvin had much success while we were watching–none of the ladies seemed to be picking up what he was laying down–but the spectacle, or lack thereof, reminded me of an old joke about Calvin Coolidge:

Calvin and his wife Gracie are each touring an experimental government farm. On her tour, Grace happens to spy a ram and a ewe…“tupping.” She asks her guide, “How many times does he do that each day?” “Dozens of times a day or more!” the oddly boundary-lacking guide replies.

“I see,” murmurs America’s First Lady.  Then, to an aide, “Please tell that to Mr. Coolidge.”

The aide, much embarrassed, approaches the President’s tour and stammers, “The First Lady would like you to know that a male sheep mates dozens of times a day.” Replies the President, “Same ewe every time?”  “No sir–a different ewe each time.”  Coolidge smiles.

“Please tell that to Mrs. Coolidge.”

Until a few months ago, I had always assumed that this almost-definitely apocryphal joke was the inspiration for naming Calvin, the ur-ram/baby-daddy of the Savage Hart flock.  It turns out that it’s not–actually, both Silent Cal and Gracie were native Vermonters, buried some 25 miles from Savage Hart, as the crow flies.  But maybe it should be, because this old, hacky joke is the namesake of one of the foundations of (animal) husbandry: the Coolidge Effect.

Take it away, Wikipedia:  “In biology and psychology, the Coolidge Effect is a phenomenon seen in mammalian species whereby males (and to a lesser extent females) exhibit renewed sexual interest if introduced to new receptive sexual partners, even after refusing sex from prior but still available sexual partners.”

Clear enough?  If not, consider the following chart, I believe originally published by Gordon Bermant in 1969 based on observations of 30 rams (including two Corriedales!) in 152 “copulatory behavior tests [tuppings]”:

 

Animal Behaviour Volume 17, Issue 4, November 1969, Pages 700–705

Essentially, male sheep (and mice and rhesus monkeys, among others) are much more wont to “perk up” in the presence of a female with whom they have not previously copulated.  Evolutionary biologists explain this as males gaining much more of an advantage by potentially impregnating a second (or third, or fourth) female, compared to an encore performance with their own Mrs. Coolidge.  Evolutionary biologists are also the source of one of the best sentences ever inserted in a serious scientific publication: “In cattle and sheep, the Coolidge Effect is so strong that the sexual limits of the experimental males have not been discovered.” (Symens, 1979) That is to say, after watching 152 copulatory tests (in a single study), the scientists blinked before the rams…blinked.

So, at some point this holiday season, if you think of the residents of Savage Hart Farm with fondness and care, spare a thought to send Calvin your best wishes.  But rest assured, he probably doesn’t need them.

Jason

* This is the sort of public confession I would have hesitated to make before a…memorable…few rounds of Cards Against Humanity with representatives of the Allen, Lambert, and Wilke clans.  Opposable thumbs!