Observations of a Nerd

Peta recently stirred up quite a lot of controversy with their banned superbowl ad claiming that “studies have shown that vegetarians are better lovers.” Of course, no such research exists, but somehow in trying find where that came from (no pun intended) I ended up in a twitter conversation about diet and sex. Anyhow, to make a long story short, after several converstaional tangents I found myself sifting through the scientific literature for anything containing “taste” and “semen.”*

Sorry, folks: there’s no scientific study of the effects of diet on human semen flavor. But what I did find was one obscure study, published in 1985 with the innocuous title “Chemoreceptively active compounds in secretions, excretions and tissue extracts of marine mammals.” In it, the scientists explain that they sought to determine if there are compounds in dolphin semen that one “may be capable of tasting.” Their abstract indicates success, as they found 22 compounds that “can be detected gustatorily… by humans.”

I simply had to find out what they meant.

Let me start by saying that the authors weren’t completely bonkers or perverted to be looking for tastable compounds in dolphin semen.

Animals use chemicals to signal all kinds of things. Chemicals draw territory lines, entice potential mates, even ward off would-be predators. Most of these are what we would call “smells” – that is, they are picked up by olfactory receptors in our noses.

Trouble is, marine mammals have mostly lost their sense of airborne smell. Even if they hadn’t, the only time a dolphin’s nostrils are open is when it surfaces to breathe, so sensing through its nose wouldn’t be all that useful for communicating with other dolphins. Furthermore, there is nothing about their anatomy to suggest that they have developed a waterborne “sense of smell” like exists in sharks. So how would a whale or dolphin pick up on chemical cues underwater? The most likely answer is, of course, through taste.

With this in mind, it seems a little less strange that a team of researchers from the University of Colorado would actively look to see what’s in various secretions from marine mammals – and, more specifically – whether those secretions contain compounds known to produce flavor.

The team took semen and urine and fecal matter from bottlenose dolphins and California sea lions and extracted the different kinds of compounds present in each. Then then identified which flavor categories these compounds fall into – sweet, sour, or bitter. No, they didn’t have people smell or taste dolphin semen or any fraction thereof, though that would have made for a much more entertaining blog post. Turns out that there are databases where one can look up if a chemical has flavor, so no in-person testing was needed for them to make these categorizations.

All bodily fluids from the marine mammals tested contained sweet compounds – mostly various kinds of sugar – and all but the poop contained sour ones. Semen and urine contained bitter components as well. Here are their tables showing the different flavor palates:
i-6ceafa9b5b58a061c12577dd64ffff1f-Screen shot 2011-02-02 at 6.12.06 PM.pngi-bc9d3b794c09ee17e58b2853ffd521b9-Screen shot 2011-02-02 at 6.15.19 PM.png
When it comes to overall flavor, though, it’s about balance: how much sweet, how much sour, etc. While it varied by sample, the most abundant chemicals in dolphin semen were
phosphoric acid (sour) and inositol (sweet), followed by glucose. In reality, though inositol is considered “sweet”, it is almost tasteless, meaning that dolphin semen probably is pretty sour stuff.

Of course, what I’m sure you really want to know is whether any of this is similar to human semen. Well: it is. Dolphin semen appears to be similar to semen from many mammals, including humans. Every compound identified in dolphin semen has been found in human semen, too. But human semen contains higher levels of sugars – specifically fructose – which is thought to serve as energy for the swimming sperm. This might make human semen a little sweeter than dolphin semen (just in case you really wanted to know).

As for altering the flavor of human semen, which is where this all began, although there are no studies directly looking at it, it is pretty safe to assume diet would have an impact. After all, diet affects the sugar levels in semen in other species. As for whether specific foods like pineapple or parsley make a guy taste sweeter: I’m afraid it’s up to you, citizen scientists, to find that out for yourselves.

*Note to self: perhaps I should limit twitter conversations with SciCurious, as they lead to posts like this one.
Dolphin image c/o Andrew Young on Flickr

ResearchBlogging.orgCitations:

CERUTI, M., FENNESSEY, P., & TJOA, S. (1985). Chemoreceptively active compounds in secretions, excretions and tissue extracts of marine mammals Comparative Biochemistry and Physiology Part A: Physiology, 82 (3), 505-514 DOI: 10.1016/0300-9629(85)90424-4

Owen, D. (2005). A Review of the Physical and Chemical Properties of Human Semen and the Formulation of a Semen Simulant Journal of Andrology, 26 (4), 459-469 DOI: 10.2164/jandrol.04104

Moule, G., Braden, A., & Mattner, P. (1966). Effects of season, nutrition and hormone treatment on the fructose content of ram semen Australian Journal of Agricultural Research, 17 (6) DOI: 10.1071/AR9660923

Comments

  1. #1 Allie
    February 3, 2011

    You know, I was mildly frightened as to where this was going when you lead with scientists wanting to know if there were dolphin semen compounds that one may capable of tasting and that 22 compounds were found that “can be detected gustatorily… by humans.”

    Thank heavens there was no actual dolphin-semen-tasting involved in this study. That might’ve been…..ewwww.

  2. #2 Southern Fried Scientist
    February 3, 2011

    I’m so proud to know you right now.

  3. #3 Chuck
    February 3, 2011

    Seriously, why is it always dolphins in these situations?

  4. #4 Scicurious
    February 3, 2011

    You are so awesome. :) Just saying.

    Also: now I’m going to freak out if I swallow ocean water.

  5. #5 Miriam
    February 3, 2011

    So. Amazing.

  6. #6 all4kindness2all
    February 3, 2011

    Noticed that the dolphin looks happy. Also, never would have seen that PETA ad without this post. Hmmm… Maybe PETA should pay folks like you instead of NBC for spreading their message?

    Wondering … Will science bloggers be twittering about their personal results next? Unconventional way for science bloggers to increase their readership?

  7. #7 tideliar
    February 3, 2011

    Christie – thanks for a truly genuine LOL :)

  8. #8 Marion Delgado
    February 3, 2011

    From memory, it’s a “witches brew” of alkaline compounds designed to lye its way past women’s defenses and knock up their eggs. Also, people evolved to regard acidic compounds, which female juices are, as less offensive than alkaline ones. Hence, the pineapple juice, which has a low pH, might offset to a tiny degree the alkilinity. Which is the theory.

  9. #9 all4kindness2all
    February 3, 2011

    Why is science always about the men? Women have fluids too! Any research done on this front? hehehe

  10. #10 William
    February 3, 2011

    What’s the deal with “banned” ads? You see so many of them online, and they are never as provocative as the word “banned” promises.

  11. #11 Archereon
    February 3, 2011

    Marion, #9 at my more base male caveman crass and crude, I have been known to quip about cunnilingus, if you go down on an indian woman, does that make you a curry muncher. I wholeheartedly apologise for the racism but enjoy the irony.

  12. #12 anon
    February 4, 2011

    >> Also: now I’m going to freak out if I swallow ocean water.

    “I never drink water; fish f*ck in it.”

    – W. C. Fields (possibly apocryphal)

  13. #13 Al
    February 7, 2011

    there does exist a proper place for this stuff: the Journal of Chemical Ecology.

    However, be prepared to mostly be reading about the sexuality of folks whose sexuality are worth paying money to learn about: crop pests.

    I understand that the female crop pests get pissed off when someone shouts at them: “hey, nice antennae!”

  14. #14 Omegle
    February 10, 2011

    Good which female juices are, as less offensive than alkaline ones. Hence, the pineapple juice, which has a low pH, might offset to a tiny degree the alkilinity.

  15. #15 Chris
    February 12, 2011

    Hi guys, I know we are all mature men and women in here. :)

    To be honest I am very much aware of this. My gf herself was the one telling me to always drink pineapple juice because according to her it indeed has an effect to the taste and try not to drink sodas. :)

    Just my two cents. :)

  16. #16 sohbet arkadaslik
    February 13, 2011

    Wondering … Will science bloggers be twittering about their personal results next? Unconventional way for science bloggers to increase their readership?

  17. #17 milt boyd
    February 14, 2011

    The US Patent Office issued a patent for various formulations intended to alter the taste of human semen. (Can’t recall the # now, but the USPO database is searchable.)

  18. #18 film izle
    February 14, 2011

    I mean, really?? I’m a scientist, and just reading that even made *my* eyes glaze over. If one thing they’re trying to convey is the importance and relevance of the scientist’s research to GQ readers, what percentage of the readers are really going to walk away with a deeper understanding of what Dr. Jamieson does by reading that description? It would have been a small thing to ask each participant to submit a layman-friendly version of their research (their “elevator talk” description, for example) for GQ to include.

    Finally–one of the “scientists” is Dr. Oz. What is he doing in there? One, I would think he’s already well-known enough; why not save that spot for another scientist? Two, yes, I know he’s actually done research and published, and is on the faculty at Columbia. Fantastic. He’s also a serious woo peddler, who has even featured everyone’s favorite “alternative” doc, Joseph Mercola, on his talk show, and discussed how vaccines may be playing a role in autism and allergies (despite mounds of evidence to the contrary). This seems to completely contradict their goal of “research funding as a national priority,” since Oz is often (and Mercola is always) highly critical of “mainstream medicine.” I really don’t understand his inclusion, and think it’s to the detriment of the rest of the campaign.

  19. #19 Christoffer
    February 18, 2011

    “The US Patent Office issued a patent for various formulations intended to alter the taste of human semen. (Can’t recall the # now, but the USPO database is searchable.)”

    I am very interested about this. Let me go ahead and search more about this and will be back here to update you guys.

    Thanks.

  20. #20 altın çilek
    March 1, 2011

    To be honest I am very much aware of this. My gf herself was the one telling me to always drink pineapple juice because according to her it indeed has an effect to the taste and try not to drink sodas. :)

  21. #21 Mike
    April 19, 2011

    Wouldn’t it have been easier to make grad students taste the dolphin semen? You wouldn’t have to tell them it was dolphin semen prior to the test, of course – in fact, good technique would prohibit it, since it would influence their judgement.