How do they account for the food-type variable? Some generate more stinky farts than others. What is the marker chemical that defines what is stinky? A smell is in the nose of the beholder.

20 hours ago, StringJunky said:

How do they account for the food-type variable? Some generate more stinky farts than others. What is the marker chemical that defines what is stinky? A smell is in the nose of the beholder.

But there’s a limit to what chemicals are typically there. I was under the impression sulfur compounds were the primary cause, with hydrogen sulfide being the most common culprit

On 4/6/2026 at 3:21 PM, StringJunky said:

How do they account for the food-type variable? Some generate more stinky farts than others. What is the marker chemical that defines what is stinky? A smell is in the nose of the beholder.

Traveling this week, so missed the replies. Apparently most beholding noses wrinkle at indoles, skatoles, and sulfides. I guess the neurological end of it is a hardwired revulsion for odors of putrefaction and other sorts of rot. Telling us in effect, "not edible, probably has bad microbes for you!"

(Someone should get a memo to Billie, a neighbor's dog who is constantly eating turds. I'll see him from the kitchen window, as I'm contemplating breakfast, and he will run out into their yard and start snarfing them down like Belgian chocolate....and then I'm no longer contemplating breakfast. And whatever time zone you, Gentle Reader, dwell in, possibly now you can put off your next repast!)

On 4/7/2026 at 11:30 AM, swansont said:

But there’s a limit to what chemicals are typically there. I was under the impression sulfur compounds were the primary cause, with hydrogen sulfide being the most common culprit

Methanethiol is another culprit especially in those with a heavy vegetable diet. Dine on a cabbage-based soup with plenty of onions and you can clear a room. But you'll have to wait at least 18 hours for it to reach the colon, where the raffinose does its gassy magic.

5 hours ago, TheVat said:

Methanethiol is another culprit especially in those with a heavy vegetable diet. Dine on a cabbage-based soup with plenty of onions and you can clear a room. But you'll have to wait at least 18 hours for it to reach the colon, where the raffinose does its gassy magic.

Which has sulfur in it. CH₃SH

6 hours ago, swansont said:

Which has sulfur in it. CH₃SH

Yes, I should have pointed out it's a thiol, the simplest one, so an organosulfur compound. Thiols are the sulfur analog of alcohols, and they all tend to smell nasty. Thiols are also what utilities add to natural gas to make leaks detectable. Some readers here might better know methanethiol as methyl mercaptan. And more complex mercaptans are the key ingredients of what skunks spray, no real surprise there. IIRC, skunks being competent chemists, use butyl mercaptan which is less volatile and so better suited to stay on the spray victim for a long while.

And I'm realizing now that methanethiol has to come from the breakdown of sulfur-containing amino acids like methionine or, in the cabbage example I gave it would likely be glucosinolates--so no idea why I mentioned raffinose except my org chem is rusty. Ignore what I said about raffinose, which mos def does not have sulfur - it's just a humble trisaccharide and would only generate H and CH4 which are the non-stinky parts of farts.

ETA: To clarify, raffinose in cabbage is like the main propellant (producing most of the gas volume) while glucosinolates in cabbage have breakdown products that include methyl mercaptan, the main pungent odorant.

Edited April 11Apr 11 by TheVat

On 3/14/2026 at 11:51 AM, toucana said:

If Isabel’s behaviour that day was odd, what she did next was unforgivable. Within a fortnight of Burton’s death, she had burned nearly all his papers: intimate diaries, notebooks, letters and manuscripts. Forty years of work by a brilliant man up in flames.

She did it, she said, to protect public morality. She saw her husband’s interest in sexuality as purely scientific, but feared others would read his journals “for filth’s sake

Something similar happened to Robert Louis Stevenson.His first manuscript of Dr Jekyl and Mr Hyde was also destroyed by his wife (for similar reasons according to Ian Rankin,I seem to remember-he said she may have thought it was "too explicit"** )

https://www.theguardian.com/uk/2000/oct/25/books.booksnews

**He made a documentary about the book and the author (I think they were/are both from Edinburgh)

11 hours ago, geordief said:

Something similar happened to Robert Louis Stevenson.His first manuscript of Dr Jekyl and Mr Hyde was also destroyed by his wife

Reported for OT digression from the serious topic of measuring flatulence. Unless of course The Guardian writer's description of the novel as "atmospheric" is referring to methane, hydrogen and various organosulfur compounds. 😉

It also occurs to me that Jekyll could have experienced alterations of his gut biome and chemistry from drinking the transformative serum which turned him into Hyde.

5 minutes ago, TheVat said:

Reported for OT digression from the serious topic of measuring flatulence. Unless of course The Guardian writer's description of the novel as "atmospheric" is referring to methane, hydrogen and various organosulfur compounds. 😉

It also occurs to me that Jekyll could have experienced alterations of his gut biome and chemistry from drinking the transformative serum which turned him into Hyde.

One thesis of Rankin's documentary was that this was fuelled by the semi industrial need for fresh cadavers in London and Edinburgh ,and that Jekyll may have been (based on?) one of those doctors (one entry for the public and a back entrance for the passage of dead bodies)

Plenty of odours and emissions in those men's nocturnal activities.

Edited April 11Apr 11 by geordief