Why do I know how to boil a frog?

As we all know, if you try to place a live frog directly in boiling water, he’ll hop out, and you’ll be left with an unboiled frog. The thing to do instead is to place the frog in lukewarm water and slowly turn the heat up. He’ll be dead and boiled before he knows what hit him.

But why do we know this? I can’t imagine that too many people need to boil live frogs, and that very few people ever have. How did this come to be an instructive metaphor?

(This came up during a discussion on the use of homotopy methods in convex optimization, and it struck me as a curious topic for a math class. Hence the question.)

  1. Frogs are part of the cuisine in many cultures, including boiled frogs.
  2. If you’re going to eat the frog anyway and are not particularly concerned with the experience from the food animal’s perspective (as many traditional cultures are not), you may well have knowledge of how to boil a live frog.

ETA: I checked my sources, but the only traditional recipes I have for frog here are frog’s legs, where the frog is killed before cooking.

That said, why couldn’t you just hold the lid down for a few seconds?

I see you’ve never been to the clambake’s southern cousin, the frogboil.

Incidentally, those spoilsports over at snopes had this to say:


I believe the first frog was boiled in an attempt to find some homotopy methods in convex optimization.

We know about it because it’s a useful metaphor for how ignoring a gradual change can lead to disaster. For example, ignoring the fact that fewer and fewer people show up for meetings will gradually lead to the demise of social club. Ignoring the gradual dismantling of the emergency response system will lead to an inability to respond when the big one hits.

The OP is asking how people came to know that a frog will not hop out of a pot if it is slowly boiled alive, in contrast with it being immediately immersed in boiling water.

We don’t know this, because it isn’t true. As Cecil once put it, the original author followed the creative process known as “making it up”. He or she probably never boiled a frog, alive or dead, at any time.

Yes, and Harriet’s point (though she didn’t make this crystal clear) is that lots of people came to know* this because it’s a piece of information that has been widely used as a cautionary tale for some time.

*Know in the sense that they have heard it, but apparently not in the sense that it’s factual (per pravnik’s Snopes link).

Well I have done the experiment myself, although it involved salamanders instead of frogs. It was in the unit on determining Critical Themal Maxima in Herpetology Lab in college. We slowly heated different species of salamanders held in glass beakers until they first became distressed and started to thrash about, then became quiet as they were overcome by the heat. We didn’t actually heat them to boiling, of course; once they passed out we lowered the heat and they recovered just fine. We found that different species had different thermal maxima, and that this was correlated with their preferred habitats in nature.

As has been stated, the purported observation in the OP is fabricated. A frog placed in a beaker and slowly heated will make frantic efforts to escape as soon as it becomes uncomfortable, no matter how slowly the heat is applied.