The Annual Holiday Chemistry Lesson From Hell: How to Tell the Age of a Fruitcake

By Josh Bloom — Dec 20, 2022
Fruitcake aficionados, my apologies in advance. It's holiday time and some of you will receive a re-gifted fruitcake that is ??? years old. But how old? You learn how to figure this out (it's the same way fossils are dated) when you read the Christmas Special “Dreaded Chemistry Lesson From Hell” below. We will also explore whether the fruitcake is the worst gift ever. From all of us at ACSH, have a happy and fruitcake-less holiday season.

Christmas is around the corner, and that means a bunch of bad gifts are heading your way. Some will be merely bad, like a calendar with a different cat hairball for every month. But even though you'd be hard-pressed to find anyone who actually wants a wall calendar, let alone one with hairballs, at least has the year on it, so it is pretty much impossible that it sitting around for decades and then regifted. No, some misguided soul spent actually spent money to purchase it. But other gifts are clearly regifted. Go ahead and try to convince me that you didn't regift a Chia Head – a strong contender for the title of "Worst Gift Ever" – back whenever those monstrosities first came out in 1981. 

Yet, the Chia Head does have some redeeming qualities. At least when you throw the damn thing out the window, it makes a satisfying sound when it hits the pavement. And if it lands on someone, it probably won't kill them. The same cannot be said for the truly hideous fruitcake, perhaps the most regifted gift of all. How do we know this? Hard evidence. My thesis is that only a few dozen fruitcakes have ever been made in the history of the world and that they exist in a hibernating state, hidden in various attics or closets, resting for 11.5 months, only to be unleashed on the world a year later. 

Let's leave that alone for a while and focus on the issue at hand: using chemistry to show how old these things really are. This means it's time for:

Steve (left) and Irving, having not seen snow in millennia, fail to properly capture the holiday spirit.

All elements have one or more isotopes, usually caused by extra neutron(s) in the nucleus. Some isotopes are stable, for example, 2H (deuterium) and 13C, and some are unstable, like 14C or all uranium isotopes. Unstable isotopes decay at known rates, emitting a nuclear particle plus energy in the process. Measuring the ratio of 12C to 14C in a sample can tell you its age. Here's how (Figure 1).

Figure 1.Carbon-14 is produced in the stratosphere by nuclear reactions of atmospheric nitrogen (14N) with thermal neutrons in cosmic rays. Once formed, 14C immediately begins to decay back to 14N with a half-life of 5,730 years. The 14C, in the form of 14CO2, is taken up by plants, just like normal carbon dioxide. As the 14CO2 (or whatever the plant has converted it to) decays, it is replenished by more 14CO2 from the atmosphere. So the plant will always contain the same level of 14C as long as it remains alive. Diagram: Wikimedia Commons

But once the plant dies, it will no longer take in 14C, so whatever radioactive carbon it contained at the time of death will steadily decay. The ratio of 14C to 12C in non-living material acts like an "atomic clock." The less 14C, the older the specimen. This ratio can be measured by a technique called mass spectrometry.

Image: Wikimedia Commons

Example: If a wood artifact has half the amount of 14C as that found in a living tree, then that wood is 5,730 years (one half-life) old. If it has only 25%, then the artifact must be 11,460 years old. After nine half-lives (51,000 years), only 0.0015% of the 14C remains, and it gets hard to measure; 14C is no longer helpful in dating specimens older than about 50,000 years. 

How Old is This Fruitcake?

In determining how many times a fruitcake has been regifted, its age may provide vital clues. Is the thing someone dumped on you five years old? 20? Let's do some math on fruitcake #17.

Fruitcake #17. Photo: Walmart

First, we tested that ear wax-looking thing marked #1. The mass spec indicated that 99.4% of the 14 C remained. If you plug that number into a handy dandy 14C dating calculator, it tells us that ear-wax thing #1 is 50 years old, putting it right in the middle of the disco era! This brings up the disturbing image of another fruitcake:

"Disco Joe" Mercola.  Image:

Next, we tested thing #2, another culinary abomination – the Maraschino cherry. Although there is an ongoing debate about whether Maraschino cherries were ever living organisms, nonetheless, its age was measurable by the mass spec. Result: The cherry was also 50 years old. 

Finally, just to be thorough, we took a core sample. This wasn't as easy as you might think.

First try. Free image: Flickr

But with a bit of effort and a titanium drill bit, a sample was obtained. 

Core sample from deep within the bowels of Fruitcake #17

I must say that I was a bit surprised by the result: only 98.1% of 14C remained. The handy dandy 14C dating calculator revealed that the fruitcake was 158 years old, putting it right in the middle of the Civil War! Perhaps it was used in place of cannonballs.

The life of fruitcake #17

We can surmise the life of #17 by making certain assumptions. Fruitcake #17 was first created and later underwent aftermarket modifications. The core sample tells us that the atrocity was first baked in 1861, perhaps as a gift to President Lincoln. A few years later, Andrew Johnson regifted it, probably to Robert E. Lee, to further rub in that he lost the Civil War. Then things become murky. During Reconstruction, life was hard, and people were starving, especially in the South, but #17 was not eaten. It is possible that starving Southerners regifted it during this time. More likely it was used to hold down a roof during tornado season.

At some time between the late 1860s and 1971, the stuff on top was scraped off, possibly for use as rat poison or to simulate vomit in Exorcist 2, and the cake portion was used as insulation for early spacecraft, or maybe to fill potholes on the Cross Bronx Expressway, which somehow managed to win the "Worst Road in the World" award for the 14th consecutive year. It is unclear whether a topless fruitcake gets regifted, but #17 reentered the regifting cycle when someone during the Disco Era, perhaps Barry Gibb, added a new topping consisting of the unknown matter and Maraschino cherries. Now, 50 years later, it emerges as a lab specimen, which some unfortunate person will receive next year. Quite a journey indeed!

Others agree

I am hardly the only anti-fruiter out there. There are websites devoted to anti-fruitcakeism (See Burning Question: Why do so many people despise fruitcake?). I ran into some pretty spiffy quotes. Here is my Christmas gift to all of you:

'The worst gift is a fruitcake. “There’s only one fruitcake in the world and people keep passing it around” (See that!)

Johnny Carson


“Airport screeners are now scanning holiday fruitcakes. Not even the scanners can tell what those little red things are.”

 David Letterman

Have you ever known anyone who bought a fruitcake for himself? Of course not. They are purchased as Christmas gifts, mostly for people you don't particularly like. 

Author: Phyllis Diller


 I would eat fruitcake if there'd been a nuclear war and I'd run out of canned goods. - Author: Deb Caletti

The easiest way to make a fruitcake is to buy a darkish cake, then pound some old, hard fruit into it with a mallet. Be sure to wear safety glasses. Author: Dave Barrett

Saving the best for last, here's some damn fine prose:

"For months they have lain in wait, dim shapes lurking in the forgotten corners of houses and factories all over the country and now they are upon us, sodden with alcohol, their massive bodies bulging with strange green protuberances, attacking us in our homes, at our friends’ homes, at our offices — there is no escape, it is the hour of the fruitcake."

Deborah Papier (a writer and editor)

(Actually, the worst/best quote by far was by Oscar Wilde, and it's in very poor taste. So much so that my colleagues yelled at me so I took it out. Look it up if you wish but don't shoot the messenger.)

I think I'll stop here and wish all of you a happy holiday season from all the fruitcakes at ACSH. 



Josh Bloom

Director of Chemical and Pharmaceutical Science

Dr. Josh Bloom, the Director of Chemical and Pharmaceutical Science, comes from the world of drug discovery, where he did research for more than 20 years. He holds a Ph.D. in chemistry.

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