# Halloween and Jank'o'lanterns and why are are pumpkins hollow? **URL:** \ **Category:** Factual Questions\ **Created:** [October 27, 2019, 2:32am UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535 "2019-10-27T02:32:34Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [October 29, 2019, 7:52am UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/41 "2019-10-29T07:52:23Z")
> [@TruCelt](#): > > What I want to know is, how does the air get in there? Think about the formation of the fruit. The interior is surrounded at all times by the skin and stem. And although the plant does respire, that it seems like an awfully big flesh/air ration for just respiration. Especially in the case of bell peppers. Think of the water lily. It has air bladders under each leaf to keep it afloat. It has to pump gas in there, and I would guess that these are filled largely with CO2. I’ll be the first to admit I don’t know the exact biochemistry behind that, though. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 29, 2019, 2:37pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/42 "2019-10-29T14:37:24Z")
> [@armedmonkey](#): > > Heh! I like that. Also Thanks to **Collibri** , **md2000** , and **Mangetout** for realizing that “humans did it” isn’t really an answer. Yes, it is, but at this point I’m taking my pearls and horse-water and going home. ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [October 29, 2019, 3:57pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/43 "2019-10-29T15:57:37Z")
Before you go, **Darren Garrison** , would you care to address how waterlilies create hollow flotation devices, or is your answer simply “human breeding”? This is a simple question with a very, very complicated answer. Which makes it perfect for GQ. Makes it perfect for the Straight Dope. This kinda thing is Cecil’s bread and butter. ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [October 29, 2019, 4:35pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/44 "2019-10-29T16:35:23Z")
Wait… Malic Acid! It’s even part of the citric acid cycle! If I remember correctly, it can bind CO2. That’s gotta be part of the answer right there. A plant will store the CO2 caused by it’s respiration by sticking it to the Malic acid and then release it later. Most do that through the underside of leaves. stomata. Water Lilies! I _knew_ there was something bouncing around in the back of my head with that. That’s how they trap the gas! If the plant covers up a stomata, and the malic acid releases the CO2 then boom, you got a botanical baloon. Now, let’s take it one step further. Fruit structures are different from leaves, obviously, but some of the same design structures just have to apply. _And_ this is waste CO2. What better way to prevent bacterial growth on your seeds than to pump CO2 into the seed pod and push out all the O2? ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [October 29, 2019, 4:37pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/45 "2019-10-29T16:37:22Z")
This is one of the best Dope controversies I’ve encountered in awhile. I found one source suggesting that pumpkins haven’t ‘‘evolved’’ or changed a whole lot over time, human breeding attempts notwithstanding. \*''Anywhere from three to 20 million years ago, two types of squash did the dirty (pollen-wise, of course) and produce what’s called an allotetraploid baby. Geneticists figured this out by sequencing the modern pumpkin’s genome and comparing it to other squashes in its family. ‘Tetraploid’ means it had four copies of each chromosomes, and ‘allo’ means that each chromosomal pair came from different species. Often when this happens the DNA eventually loses genes and over time becomes diploid again. Not so with pumpkins. Pun’kins lost their duplicate chromosomes randomly, leaving them with just two of each chromosome, one from each parent—which is almost human of them. Since the pumpkin genome hasn’t changed a whole lot since then, that means today’s jack-o-lanterns are almost identical to ancient ones (assuming that early humans carved gourds)."\* > **[Pumpkins evolved from a literal genetic (monster) mash-up](https://www.popsci.com/pumpkin-plant-genetics/)** > > Pumpkins are, arguably, the least spooky part of Halloween. They are also the least contentious (see: candy corn), the most orange, and—scientifically speaking—the coolest. Elsewhere it’s noted that squash/pumpkin ancestors had tough outer shells (no word on “hollow” interiors) and that breeding efforts over time resulted in softer rinds that were easier to break down as well as tasting better. [http://nationalgeographic.com/science/phenomena/2015/11/16/why-pumpkins-and-squashes-arent-extinct/](http://nationalgeographic.com/science/phenomena/2015/11/16/why-pumpkins-and-squashes-arent-extinct/) My take on why pumpkins and squash aren’t as dense as some vegetables/fruits may relate to numerous factors including preservation of seed fertility and ease of spread, partly via the digestive tracts of animals. Hard to imagine many beasts that would want to eat stringy pulp and gulp down seeds whole in preference to solid pumpkin/squash flesh, but I’m not a mammoth or whatever creature still eats these things in the wild. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 29, 2019, 4:54pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/46 "2019-10-29T16:54:57Z")
> [@armedmonkey](#): > > Wait… Malic Acid! It’s even part of the citric acid cycle! If I remember correctly, it can bind CO2. That’s gotta be part of the answer right there. A plant will store the CO2 caused by it’s respiration by sticking it to the Malic acid and then release it later. Most do that through the underside of leaves. stomata. Water Lilies! I _knew_ there was something bouncing around in the back of my head with that. That’s how they trap the gas! If the plant covers up a stomata, and the malic acid releases the CO2 then boom, you got a botanical baloon. > > Now, let’s take it one step further. Fruit structures are different from leaves, obviously, but some of the same design structures just have to apply. _And_ this is waste CO2. What better way to prevent bacterial growth on your seeds than to pump CO2 into the seed pod and push out all the O2? Why are you hung up on CO2? If plants or fruit or seeds have some hollow space in them I would assume that it’s filled with air. Are there any of these that are air tight before they dry? I assume as they grow they are porous enough to ‘inhale’ air. And I recall that some floating plants that may include water lilies have some kind of filaments that basically hold air bubble in place under them and around their stems. ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [October 29, 2019, 5:24pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/47 "2019-10-29T17:24:11Z")
> [@TriPolar](#): > > Why are you hung up on CO2? I wouldn’t say that I am hung up on it. I’m just spitballing, man. You’re also correct in that waterlillies have “hairs” on the bottom that trap bubbles (I used to grow them), but they _also_ have bladders. And you can pop them! For the plant to keep the pressure in those bladders, it’s got to be CO2 right? OK, consider Kelp. Not exactly a plant per se, but close enough enough for this conversation. It spends it’s entire life underwater, but it uses gas filled bladders. That gas has to come from someplace, and it’s not the ambient environment. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 29, 2019, 9:15pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/48 "2019-10-29T21:15:19Z")
> [@armedmonkey](#): > > Before you go, **Darren Garrison** , would you care to address how waterlilies create hollow flotation devices, or is your answer simply “human breeding”? We weren’t talking about water lilies–we were talking about the fruits of pumpkins. They are not directly related to the human invention known as the jack-o’-lantern pumpkin. Water lilies have hollow spaces in their stems that help them float (as do lotuses.) Lots and lots of plants have stems with hollow spaces, especially herbaceous plants that grow quickly and die back in one season–[elephant ears](https://vietherbs.com/herb-directory/elephant-ear/) and _Amorphophallus sp_. I know have them from my growing them. It is probably a widespread trait across arums. There are plants and plant-ish things with actual special flotation devices, too, including [bladderworts](https://en.wikipedia.org/wiki/Utricularia#Physical_description_of_the_trap) and [some brown algae](https://en.wikipedia.org/wiki/Pneumatocyst). For all of them, the answer to “how” is going to be some highly technical (and possibly insufficiently studied) description of the interactions of genes and proteins, including especially protein pumps in cell membranes moving specific types of molecules across pressure gradients. For example, from the Wikipedia entry for bladderworts, we have this: > [@](#): > > Utricularia have significantly greater respiration rates than most vegetative tissue, primarily due to their complex energy-dependent traps. Upon triggering, prey is captured through a two-step ATP-driven ion-pumping process where organisms are sucked in by internal negative pressure achieved by pumping water out of the trap and into the external environment. Recent research suggests that COX subunit I (COX1), a rate limiting enzyme in the cellular respiration pathway associated with the synthesis of ATP, has evolved under positive Darwinian selection in the Utricularia–Genlisea clade. There appear to be adaptive substitutions of two contiguous cysteines (C-C motif) at the docking point of COX1 helix 3 and cytochrome c. This C-C motif, absent in ~99.9% of databased Eukaryota, Archaea, and Bacteria, suggests a conformational change that might decouple electron transport from proton pumping. Such decoupling would allow Utricularia to optimize power output (energy × rate) during times of need, albeit with a 20% cost in energy efficiency. All “hows” are going to be something like that. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 29, 2019, 9:36pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/49 "2019-10-29T21:36:44Z")
- > [@](#): > > Since the pumpkin genome hasn’t changed a whole lot since then, that means today’s jack-o-lanterns are almost identical to ancient ones (assuming that early humans carved gourds). - Except for the slight problem (which has been pointed out) that the pumpkin is just one of a variety of plants humans derived from the same ancestor. The pumpkin and the zucchini–for example–[are two human-built varieties of the same species of plant](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3284661/). In other words, the ancient pumpkin and the ancient zucchini are the same thing–and they don’t look that similar, [especially in cross-section](https://www.jessicagavin.com/zucchini-101/). ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [October 31, 2019, 4:55pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/50 "2019-10-31T16:55:28Z")
So has anyone actually tested the gas inside a pumpkin to see whether it is just normal air, or CO2, or some kind of special Halloween swamp gas? ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [October 31, 2019, 5:13pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/51 "2019-10-31T17:13:30Z")
> [@Alessan](#): > > IIRC, strawberries aren’t actually fruit - each “berry” is actually a cluster, which can explain the voids. This thread is largely an example of another type of cluster. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 31, 2019, 5:31pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/52 "2019-10-31T17:31:42Z")
> [@Mean\_Mr.Mustard](#): > > This thread is largely an example of another type of cluster. **Moderator Note** If I take your meaning correctly, this appears to be a threadshit. In any case, let’s refrain from remarks like this that make no constructive contribution to the thread. If you believe posts to be in error, please address this directly rather than making snarky remarks. Colibri General Questions Moderator ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [October 31, 2019, 8:00pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/53 "2019-10-31T20:00:53Z")
The thread title’s reference to a “Jank’o’lantern” had me wondering if that was a pumpkin carved to resemble onetime South Dakota governor William Janklow, which is a nightmarish Halloween thought. :eek: ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [October 31, 2019, 10:07pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/54 "2019-10-31T22:07:04Z")
> [@Colibri](#): > > **Moderator Note** > > If I take your meaning correctly, this appears to be a threadshit. In any case, let’s refrain from remarks like this that make no constructive contribution to the thread. If you believe posts to be in error, please address this directly rather than making snarky remarks. > > Colibri > General Questions Moderator I was actually just trying to be amusing, but yeah, I see it now. Apologies. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 31, 2019, 10:37pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/55 "2019-10-31T22:37:11Z")
> [@Mean\_Mr.Mustard](#): > > I was actually just trying to be amusing, but yeah, I see it now. Apologies. Thanks. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [October 31, 2019, 10:58pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/56 "2019-10-31T22:58:50Z")
> [@Darren\_Garrison](#): > > Again, with the bell pepper, you are seeing the result of hundreds to thousands of years of human selective breeding, not natural evolution. The ancestors of all peppers would have been small fruits with small spaces around the seed–it is only because of human breeding that the hollow space has became huge as the fruit becomes huge becases the “flesh” of the fruit doesn’t grow in thickness in proportion to the fruit growing in volume. That’s likely the thing with pumpkins and peppers–there are genes to work with to make the fruit huge, but not genes to make the flesh proportionaly thick ??? The bell pepper I just bought from the supermarket looks (approximately) proportionally bigger than the tree peppers I saw growing wild as a kid, and very similar to the hot peppers I grew in our garden. Which had thin skin and smaller voids in proportion to their smaller overall size. ---
**Author:** ![carnut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnut/32/3531_2.png) [@carnut](https://boards.straightdope.com/u/carnut)\ **Post date:** [November 1, 2019, 9:50pm UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/57 "2019-11-01T21:50:44Z")
> [@Colibri](#): > > But why shouldn’t they have spaces around the seeds? It may simply be because of the way the fruit grows. There doesn’t have to be a positive adaptive reason why there are spaces around the seeds. > > In the classic paper [The Spandrels of San Marco and the Panglossian Paradigm](https://en.wikipedia.org/wiki/The_Spandrels_of_San_Marco_and_the_Panglossian_Paradigm) Stephen Jay Gould and Robert Lewontin pointed out the fallacy of looking for an adaptive reason for every feature of an organism. The spandrels of St. Marcos Cathedral are features that appear to have been deliberately designed for their own sake but are simply a side result of the architectural structure. Similarly the growth pattern of a fruit may result in empty spaces, even though there is no adaptive reason for them (and no selective reason against them). > > My favorite example of such a “spandrel” is the human butt-crack. You may well ask the adaptive reason why we have such a prominent crease in our backsides. But really, the adaptive feature is our hypertrophied gluteus maximus muscles, which enable us to stand erect. The butt-crack is simply a result of having such large expanded muscles side by side, and has no adaptive reason itself. Now I’m going to confuse spandrels with squinches, dang it. And think about it when I shower. :smack: ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [November 3, 2019, 1:21am UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/59 "2019-11-03T01:21:07Z")
> [@Colophon](#): > > So has anyone actually tested the gas inside a pumpkin to see whether it is just normal air, or CO2, or some kind of special Halloween swamp gas? That’s pretty much what I’m wondering. It’s an interesting question. Well, at least I think so. And to the board in general: I’m sorry this thing has become a bit of a Charlie Foxtrot, it was not my intention. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 3, 2019, 2:56am UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/60 "2019-11-03T02:56:49Z")
[Here](http://www.bigpumpkins.com/MsgBoard/ViewThread.asp?b=3&p=427845) is a thread from a more focused forum. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [November 3, 2019, 6:46am UTC](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535/61 "2019-11-03T06:46:59Z")
> [@Darren\_Garrison](#): > > [Here](http://www.bigpumpkins.com/MsgBoard/ViewThread.asp?b=3&p=427845) is a thread from a more focused forum. Good find. So basically air but with a little more CO₂ and a little less oxygen? [Previous page](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535.md?page=2) [Next page](https://boards.straightdope.com/t/halloween-and-jankolanterns-and-why-are-are-pumpkins-hollow/842535.md?page=4)