A new law of biology: All mammals pee for about 21 seconds

A new paper by P. J. Yang et al. at ArXiv.org (reference and free download of the first page below) has produced a new Law of Biology.  The whole paper isn’t online, and I don’t know where it was submitted, but. . . .well, the title speaks for itself:

Picture 3

And what is that duration, exactly? The abstract says about 21 ± 13 (is that the standard deviation among species?) seconds:

Picture 2

I don’t completely get this, but hey, it’s physics, Jake.  How does simply lengthening the urethra increase the flow. What about its width?  The penultimate sentence is ambiguous, perhaps smacking a bit of teleology, since a system can’t evolve for future contingencies, like being scaled up without hurting its function. But that may be some kind of shorthand.

A precis at Seriously, Science? on the Discover blogs just reiterates the paper, but adds a video showing micturation in mammals (you get a bonus defecation with the elephant), and then some geometry and algebra presented quickly, showing that the duration of urination increases only as the sixth root of body mass (mass^0.1666), i.e., very slowly, so that a large mammal will have pretty much the same duration as a small mammal.  Maybe you physics buffs can figure it out from the quick presentation on this video:

If you understand their conclusion based on the geometry and algebra, please explain in a comment.

I eagerly await the publication of the full paper. In the meantime, I think we should all start timing ourselves.

_________

Yang, P. J., J. C. Pham, J. Choo, and D. L. Hu. 2013. Law of Urination: all mammals empty their bladders over the same duration. submitted

76 Comments

  1. alexandra moffat
    Posted October 18, 2013 at 10:44 am | Permalink

    …and now there will be a study to discover how many minutes over a lifetime a human spends at the end of a leash, waiting….

    • Paul Spence
      Posted October 18, 2013 at 11:26 am | Permalink

      I’ve just put one of my dogs on furosemide, a diuretic. She now pees for a significantly longer period of time after about 30 minutes. This evening I will place myself on a diuretic (diluted EtOH) and time myself.

  2. Brian
    Posted October 18, 2013 at 10:48 am | Permalink

    So far about 20 seconds for me.

    • W. Benson
      Posted October 18, 2013 at 6:42 pm | Permalink

      Depends on how much beer?!

  3. gbjames
    Posted October 18, 2013 at 10:51 am | Permalink

    Is this with or without the use of Flomax?

    • Posted October 18, 2013 at 7:48 pm | Permalink

      I was just gonna mention the male variable…

  4. marvol19
    Posted October 18, 2013 at 10:55 am | Permalink

    “nearly constant duration of 21 +- 13 seconds”.

    I read that as “anything between 8 and 34 seconds” which seems hardly constant, really. That’s more than a factor of four range.

    • gbjames
      Posted October 18, 2013 at 10:57 am | Permalink

      Good point. It is kind of like saying “All mammals can empty their bladders within about half a minute.”

    • eric
      Posted October 18, 2013 at 11:37 am | Permalink

      I think that’s still quite a surprisingly narrow range, if it’s true. Consider that (again, if true), this factoid covers everything from blue whales to the hog-nosed bat.

      ***

      On a different note, methinks someone is angling for a 2014 Ig Nobel prize.

      • lamacher
        Posted October 18, 2013 at 1:22 pm | Permalink

        I agree with Eric. Anyone who walks a small, active terrier will know that this study is bollux, even if you add up all the half-second squirts on all sites that require information deposition. An IgNobel for sure!

        • John Scanlon, FCD
          Posted October 31, 2013 at 5:27 am | Permalink

          That’s scent-marking, not proper urination, so not a valid comparison.
          The correct spelling is bollocks (unless used as a verb, I think).

      • gravelinspector-Aidan
        Posted October 19, 2013 at 3:04 am | Permalink

        On a different note, methinks someone is angling for a 2014 Ig Nobel prize.

        Don’t they have to measure the effect of the liquid on the dunk-strength of biscuits too? Or do you think that’s their strategy for getting two Igs in a row?

  5. Diana MacPherson
    Posted October 18, 2013 at 10:56 am | Permalink

    Well I now have no choice but to time myself.

    • Alex Shuffell
      Posted October 18, 2013 at 2:17 pm | Permalink

      That makes much more sense! I read the advice to do our own measurements, the video then cut quickly to some students interested in the underside of a goat. I was about to start preparing for a visit to Pennywell Farm.

  6. Posted October 18, 2013 at 10:58 am | Permalink

    Anything in there about the percentage that does it on the rug?

    b&

    • eric
      Posted October 18, 2013 at 12:28 pm | Permalink

      How about the percent of males that miss the bowl? 😉

      • gbjames
        Posted October 18, 2013 at 12:29 pm | Permalink

        Constant across all species.

  7. Gareth Price
    Posted October 18, 2013 at 10:58 am | Permalink

    From the point of view of humans, it would be interesting to know whether 21 +/- 13 seconds is also the average length of a commercial break during a TV show.

    • Diane G.
      Posted October 18, 2013 at 9:48 pm | Permalink

      If only.

    • Anthony
      Posted October 21, 2013 at 10:49 am | Permalink

      It is the length of one commercial (30 seconds, though there are 15-second spots here and there). The other commercials are to allow you to get to and from the toilet.

  8. Matt G
    Posted October 18, 2013 at 11:00 am | Permalink

    What mouse has a bladder volume of 100 ml? The whole mouse doesn’t fill that much space.

    • Diane G.
      Posted October 18, 2013 at 9:50 pm | Permalink

      My question too!

  9. Alex Shuffell
    Posted October 18, 2013 at 11:02 am | Permalink

    The longest time a human has spent urinating is 36 minutes and 24 seconds by a British bloke called George Wingfield in 1986. He had drunk 45 pints of lager before. I hope this information has been useful.

    • infiniteimprobabilit
      Posted October 19, 2013 at 11:23 pm | Permalink

      Continuously?

      Umm. 45 pints? I find that hard to believe…

  10. Allen
    Posted October 18, 2013 at 11:13 am | Permalink

    I have to stop reading this during lunch.

  11. Posted October 18, 2013 at 11:17 am | Permalink

    OK, I hadn’t thought of it before, but it’s not a big surprise. Most mammals (exceptions such as parrots and humans exist) live for about a billion heartbeats. If size of the bladder increases, increasing size of the urethra will allow it to empty more quickly, so that time is independent of size.

    • Ryan
      Posted October 18, 2013 at 11:21 am | Permalink

      parrots = mammals 🙂

  12. Richard Olson
    Posted October 18, 2013 at 11:27 am | Permalink

    A drinking contest back in the day in a college town: order a 60 oz pitcher of beer, one per contestant seated at the same table, to be consumed in a one ounce gulp, one shot of beer every 60 seconds on the clock. Begin with the first serving of alcohol of the day (highly recommended), or take your chances when you’re partway into the bag. Losers pay for the pitchers. Side bets allowed/encouraged.

    Anyone who left the table to whiz before the pitcher emptied and the end of the hour is a loser.

    Some cylindrical beer steins with concave bottoms on the base hold exactly an ounce, and the main place I knew of where the game was frequently played, in a town with dozens of bars, was a particular bar that used these mugs. People challenged others to meet them: Mel’s on Tuesday night? Happy to take you on, sucker, I’ll be there.

    I witnessed few people able to empty their pitcher before leaving to empty their bladder, but that may have been because many contestants primed for the event with beer. I can’t speak to urination times for participants in these contests, but personal anecdotal experience is volume and pressure are both quite high.

    • Graham Martin-Royle
      Posted October 18, 2013 at 11:43 am | Permalink

      Sounds a bit like the 100 club. Try to drink 100 shots of beer in 100 minutes. Sounds easy, a shot of beer every minute, how hard can that be? I’ve seen people on their knees throwing up before they’ve got to 10.

      • gbjames
        Posted October 18, 2013 at 11:48 am | Permalink

        But it beats drinking the prep for a colonoscopy!

        • Diana MacPherson
          Posted October 18, 2013 at 11:51 am | Permalink

          I think the worst is if you have to have an ultrasound – pregnant women have this and I had to have it to look at my ovaries – they tell you to drink a bunch of water beforehand then not pee as the tech runs an ultra sound wand over your bladder! Torture! I actually begged them to let me pee some out first (and I’m proud to say I had to control to do so but enough was in for the procedure). I was really cranky that day.

          • Posted October 18, 2013 at 1:53 pm | Permalink

            Well, I’ve never been pregnant, but I went through the same procedure to check my kidney function after I was diagnosed hypertensive (193/smth).

            It was not fun.

            /@

            PS. The ultrasound staff are, of course, the most dependable people in a hospital.

            PPS. On meds, I’m now around 13x/8x.

            • Diana MacPherson
              Posted October 18, 2013 at 3:47 pm | Permalink

              I wasn’t pregnant either. I had to get a look at my ovaries.

              • Posted October 19, 2013 at 2:05 am | Permalink

                I don’t have ovaries either!

                /@

              • Diana MacPherson
                Posted October 19, 2013 at 6:13 am | Permalink

                Awww too bad. You’re missing out! 🙂

        • Richard Olson
          Posted October 18, 2013 at 11:51 am | Permalink

          No longer true. I had one last June, and it was like drinking fruit juice, only less sugary. A huge improvement over earlier concoctions.

          • Richard Olson
            Posted October 18, 2013 at 12:00 pm | Permalink

            “Had one” referring to a colonoscopy, of course. I’ll take Diana’s word for pregnancy and ultrasound treatment.

        • bonetired
          Posted October 18, 2013 at 12:00 pm | Permalink

          Oh nooooooo! Picolax ! Evil evil stuff!

        • David Duncan
          Posted October 18, 2013 at 4:16 pm | Permalink

          Years ago that stuff was torture but it is much much nicer now. Not something I would drink by choice but vastly better than eight years ago.

          • Jeff L
            Posted October 19, 2013 at 7:59 am | Permalink

            Ugh. I had to get a colonoscopy about a year ago, and the drink was horrible. If it was worse before, I feel sorry for the people who had to drink that.

            As far as the drinking games, we used to call the power hours and century clubs. Definitely harder than it sounds like (for me, the carbonation was the worst).

          • gbjames
            Posted October 19, 2013 at 8:02 am | Permalink

            I’ve had the older stuff (a gallon of really, really, awful stuff). I’ve had the newer stuff (a half gallon of Gatorade mixed with powdered awful). The newer stuff is not nearly as bad as the older stuff. It is still awful.

    • Posted October 18, 2013 at 10:32 pm | Permalink

      Careful with these drinking-without-pissing contests. They can kill you. Especially if water is the fluid you have to consume.

      • infiniteimprobabilit
        Posted October 19, 2013 at 11:27 pm | Permalink

        As Tycho Brahe famously found. (Not with water, though).

  13. drew
    Posted October 18, 2013 at 11:35 am | Permalink

    For a full load, so to speak, I normally have a time of about 52 seconds.

    My personal best was 1m 23s. This occurred while inebriated during college.

    • Diana MacPherson
      Posted October 18, 2013 at 11:44 am | Permalink

      My worst experience was actually having a hard time peeing because of holding it for so long. Poor muscle couldn’t relax! It was too late of an intermission during a Shakespeare play (I think it was The Tempest) & I stupidly had had an alcoholic beverage before the show started.

      • Posted October 18, 2013 at 1:53 pm | Permalink

        No apposite quotation from the play?

        /@

        • Diana MacPherson
          Posted October 18, 2013 at 3:48 pm | Permalink

          I’d have to go to the trouble of looking it up. Mostly I use “ban ban caliban” to talk about the Taliban or kanban boards.

      • infiniteimprobabilit
        Posted October 19, 2013 at 11:28 pm | Permalink

        Yes, it happens to males too. (The holding-it-too-long can’t-go problem).

  14. Steven Obrebski
    Posted October 18, 2013 at 11:47 am | Permalink

    According to Wikipedia the term pissing contest can refer to futile or puroposeless and excessively agressive verbal disputes or as a pejorative metaphorical description of aggresive or vulgar egoistic behavior. This tactic was tried by the Republicans recently but apparently their more refined opponents prevailed.

  15. Dave
    Posted October 18, 2013 at 11:57 am | Permalink

    Never mind about the time spent having a Jimmy Riddle – do all mammals take the same time having a dump?

    I’d imagine that the curry factor might play a part in the latter…

  16. Steven Obrebski
    Posted October 18, 2013 at 12:27 pm | Permalink

    River otters have specific dump sites on the shore. Evidently this serves a communication
    function. Any otter can sniff it and get the straight poop who is in the neighborhood and deposit a message about its arrival. A study in Alaska showed that otter poop was a significant source of nitrogen for near shore vegetation. Of course pissing around the neighborhood serves the same function. We fed a neighborhood tom cat for a while which performed magnificent squirts, but after it killed off a number of potted plants we trapped it and had it chopped and channeled (as the saying goes) and he eventually became a tame house cat.

    • eric
      Posted October 18, 2013 at 12:32 pm | Permalink

      Rhinos and a bunch of other animals also create group middens. Seems to be a fairly common trait.

  17. Posted October 18, 2013 at 12:32 pm | Permalink

    How incredibly stupid (of me) to not think of that!

  18. infiniteimprobabilit
    Posted October 18, 2013 at 12:38 pm | Permalink

    That comment about lengthening increasing gravitational force AND flow rate is nonsense. Increasing the length (assuming same diameter) increases the head differential (‘gravitational force’) but also the total viscous ‘friction’ in the fluid. Assuming a vertical pipe, you have the entry loss, the exit loss, and the ‘friction’ loss in between. For a long thin pipe, the first two of those are negligible compared with the third; the flow rate on lengthening will stay the same. Of course, IF the diameter increases proportionately with the length, THEN the flow rate will increase.
    This all applies of course to an ideal straight uniform rigid pipe (probably attached to a spherical cow…)

  19. Stephen Barnard
    Posted October 18, 2013 at 12:54 pm | Permalink

    That sounds about right. Is this a case of “not even wrong?”

  20. Posted October 18, 2013 at 12:54 pm | Permalink

    Shouldn’t it be the Law Of Micturition?

  21. Posted October 18, 2013 at 1:08 pm | Permalink

    Ponder the fate of Danish astronomer Tycho Brahe. From his Wikipedia page: “Tycho suddenly contracted a bladder or kidney ailment after attending a banquet in Prague, and died eleven days later, on 24 October 1601. According to Kepler’s first hand account, Tycho had refused to leave the banquet to relieve himself because it would have been a breach of etiquette.[24][25] After he had returned home he was no longer able to urinate, except eventually in very small quantities and with excruciating pain. The night before he died he suffered from a delirium”

  22. MICREG
    Posted October 18, 2013 at 1:12 pm | Permalink

    Emptying its bladder can eventually be a time during which the mammal becomes vulnerable to predation and independently of this hypothesis, emptying its bladder seems to exhibit few functions: to eject the urine and in some cases to mark territory.
    It seems intuitive that the action of territory marking by ejecting some urine must be as short and efficient as possible in order not to be vulnerable to predation or to concurrent males and it seems intuitive that a long time of urine ejection cannot exhibit any kind of advantage.
    Thus maybe the shorter possible time is selectioned because it is also the less expensive in terms of natural selection and maybe inside the mammalian bladder structure there is a physiological and physical limit in this race to shortening the urination duration, so that independently of the mammal species (and their difference in body measurements) this time is converging toward an inferior limit, so that we have the impression of a constant.
    And I can add that there can be a great variability of this duration in function of the emotional state of an individual, so that I don’t believe that this report shows a new law of biology but only one of the consequence of natural pression of selection, which seems here the main biological law.

  23. Wildhog
    Posted October 18, 2013 at 1:48 pm | Permalink

    So these old guys who take 3 minutes to pee aren’t mammals?

    • Posted October 18, 2013 at 2:00 pm | Permalink

      No, but they are Socrateses…

      b&

  24. Barry
    Posted October 18, 2013 at 1:49 pm | Permalink

    They obviously did not include kangaroo rats in their study.

  25. AdamK
    Posted October 18, 2013 at 2:36 pm | Permalink

    I am intimately acquainted with a small Pomeranian mammal who purposefully retains his urine so he can dribble out a few drops every now and then, here and there, all over the damn place.

    • wildhog
      Posted October 18, 2013 at 4:08 pm | Permalink

      I have a book on dogs that says dog bladders cannot completely empty on a single pee. Dont know if thats true but if so, you cant blame the Pomeranian mammal for purposefully retaining.

  26. Dave
    Posted October 18, 2013 at 3:27 pm | Permalink

    And the point of this “study” was what, exactly?

    • John Scanlon, FCD
      Posted October 31, 2013 at 5:38 am | Permalink

      Science, of course!
      There are zoos, and animals in zoos, and millions of people who would queue up to volunteer to spend any amount of time watching animals without having to feel they should be doing something more boring. Hand out a few stopwatches (or these days, smartphones) and you’re doing Science.

      00:22.25 🙂

  27. Simon Hayward
    Posted October 18, 2013 at 3:32 pm | Permalink

    I have been peed on by many mice and they usually manage to deliver the whole load – it wouldn’t take 21±13 seconds to drop them.

    Seriously though, in mice micturation patterns are strain specific, some strains pee large volumes (large by mouse standards anyhow) some do a drip here and a drip there. It’s a confounding factor when comparing results of, for example, partial bladder outlet obstruction studies. You have to know your strain. There is also variation in patterns between dominant and submissive rodents – submissive rats often pee furtively and quickly in one corner of the cage while dominant ones pee wherever and for as long as they please.

    They didn’t even need to go to the zoo to do the studies there is a whole literature on this, they just need to look. This looks like a “law” that will be defined by its many exceptions

  28. David Duncan
    Posted October 18, 2013 at 4:22 pm | Permalink

    I think they need to add a variable for age in there.

    • Posted October 20, 2013 at 2:42 pm | Permalink

      Maybe. I didn’t get a consistent length of time.

      Once, 10 seconds, then 30 with a very full bladder, then 20 secs.

  29. Hempenstein
    Posted October 18, 2013 at 7:00 pm | Permalink

    As one of my fellow grad students used to say, “You don’t say? How very interesting.”

    And then there are the studies on ejaculation performance with terms like muzzle velocity. A colleague once showed me one such paper. Single au, and from the footnotes it was clear that the experimental subject was himself.

    • Hempenstein
      Posted October 18, 2013 at 7:01 pm | Permalink

      (Just to be clear, colleague and au not the same.)

    • Diana MacPherson
      Posted October 18, 2013 at 8:09 pm | Permalink

      Muzzle velocity. Hmmmmmm.

  30. Posted October 18, 2013 at 8:36 pm | Permalink

    And to think this paper comes right on the heels of the announcement in the Bulletin of the American Physical Society of the upcoming presentation on urinal dynamics at the 66th Annual Meeting of the APS Division of Fluid Dynamics (biofuids session).

    These are heady days for urine scientists.

    • Diane G.
      Posted October 18, 2013 at 9:59 pm | Permalink

      Super pun!

  31. marksolock
    Posted October 19, 2013 at 11:15 am | Permalink

    Reblogged this on Mark Solock Blog.

  32. Sagra
    Posted October 20, 2013 at 8:36 am | Permalink

    It takes longer if you are Tweeting. Not sure if that applies to birds, though.


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