Peeing And Becoming

There was an amusing anecdote in my family about my long-departed Scottish grandmother, who, in the course of helping to potty-train one of her grandchildren (indeed I think it might have been yours truly), attempted to stimulate the “wee bairn” by running the water in the sink. The plan, however, immediately backfired, and she ended up having rather suddenly to usurp the throne herself, amid gales of laughter from those present.

This story popped into my mind this evening, and made me wonder: just how did we acquire that response to the sound of running water, anyway? As a good Darwinian, I have to imagine it is likely to have been in some way adaptive, but how did such an adaptation arise?

A guess: perhaps the masking effect of the sound provided an opportunity for our ancestors to relieve themselves in stealth when they might otherwise have been overheard by a predator, or revealed themselves to prey.

Any thoughts, readers?

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  1. JK says

    I’ve some ideas however I’m not as able as some of … well Peter for instance. I will admit the ex bought an indoor fountain that kept me up at night, soon yard saled.

    She however had her own (like your Grandmum apparently) habit of farting in the Wal-Mart checkout line then -prior to the full effect – turning and hotly chiding, “Damn you JK !!”

    Posted September 28, 2009 at 10:03 pm | Permalink
  2. Jack says

    Not every trait is an adaptation. And even if one were able to come up with a plausible explanation of how some trait might be adaptive in some environment, that is merely the first step in many one must take to link that proposed effect of the trait with its genesis. Evolution is a historical process, and requires historical explanations!

    Posted September 29, 2009 at 2:31 pm | Permalink
  3. Malcolm says

    I agree that not every trait is an adaptation — Gould coined the term “spandrels” for those that aren’t — but this one, I have a feeling, is; it seems too universal, and I think we can all agree that in some circumstances it is costly.

    Posted September 29, 2009 at 2:46 pm | Permalink
  4. We tend to yawn when others do. Is that useful? I suppose that there’s safety in numbers. Perhaps people peed together because it was safer than alone. If you set out to pee, you generally walk off away from the camp, and nobody wants to do that alone . . . not at night, anyway. The urge to pee when hearing running water might stem from that practice as a side-effect.

    Jeffery Hodges

    * * *

    Posted September 29, 2009 at 6:17 pm | Permalink
  5. Malcolm says

    An interesting thought, Jeffery, though by the time I hear you doing your business and get up to join, you’re already off on your own, and probably finishing up.

    Posted September 30, 2009 at 10:40 am | Permalink
  6. Jack says

    I don’t know that it isn’t a “learned” response to the sound of peeing in the toilet Peeing on soggy soil in the Amazon won’t make that sound. Could be the result of general associative learning, or empathetic response. What evidence do we have that Amazonian aboriginals (those not living with plumbing) have the same response?

    To be fair I’ve had your thought more than once, but I cannot find a convincing way in which it would be adaptive. Removing everybody’s urine away from you might be beneficial, but only really if everyone else is doing it (the benefit is frequency dependent), and only at rather high population densities. Defecation is a much more toxic waste, and the sound of running water doesn’t inspire me to defecate…


    Posted September 30, 2009 at 1:24 pm | Permalink
  7. Malcolm says

    “What evidence do we have that Amazonian aboriginals (those not living with plumbing) have the same response?”

    A fair question – though they’ve been isolated so long that it might be a shared adaptation even if they don’t.

    I doubt it is a learned response, as it is clearly present in infants.

    Posted September 30, 2009 at 2:27 pm | Permalink
  8. bob koepp says

    Clearly present in infants? Every infant I’ve encountered seemed to pee “whenever.” The only thing predictable was that _after_ peeing, there was a (very) temporary reprieve.

    Posted September 30, 2009 at 6:10 pm | Permalink
  9. Malcolm says

    Well, I actually tried it out on my kids, and it seemed to work. Certainly I don’t recall ever learning (not to mention teaching) this response. It seems pretty universal, as far as I can tell, though obviously I make no claims to scientific thoroughness here.

    Posted September 30, 2009 at 6:16 pm | Permalink
  10. A related – and equally provocative question – is: When did homo sapiens decide it is shameful to pee or poop in public? Animals just relieve themselves whenever and wherever the urge strikes. Properly toilet trained humans “hold it” until they can get to an appropriate facility or appropriately private spot.

    Posted October 4, 2009 at 11:04 pm | Permalink
  11. Malcolm says

    Hi Stiletto, and thanks for stopping by. That is indeed a pertinent question, to which I haven’t an answer.

    Posted October 5, 2009 at 12:06 am | Permalink
  12. frost says

    If you’ve ever hiked the Kaibab Trail into the Grand Canyon you’ve probably noticed that the mules all relieve themselves at the same time. You’ll walk for a mile or two on a completely dry trail and then come upon a veritable swamp of urine and dung covering 20 to 50 yards.

    My thought is that predators could use a continuous trail of odoriferous excretions to locate groups of prey. If every one of the members of the group unload in the same spot then there is less of a clue as to their presence and which way they went. Yes, there will still be an odor trace where they walked but this is much harder to detect from a distance and will dissipate sooner than excreta.

    Posted October 9, 2009 at 12:22 pm | Permalink
  13. wisp says

    I think i really got this.

    Peeing is good because it disposes of waste.

    Being hydrated is good so we don’t die.

    A balance is needed.

    When you hear water running, that’s a good hint to stop economizing water. You’ll be drinking soon enough.

    Posted November 19, 2009 at 12:55 am | Permalink
  14. wisp says

    What some say about not giving yourself away by spreading your odor seems to oppose the male’s urge to pee on tree trunks.

    Perhaps that’s not an instinct, but i think it is.

    Posted November 19, 2009 at 12:59 am | Permalink
  15. Malcolm says

    Good one, wisp! That’s a very interesting suggestion.

    To play Devil’s advocate: I don’t know of any mechanism by which the body can reclaim water from its urine, so it’s hard to see why keeping it in the bladder helps in any way.

    Posted November 19, 2009 at 1:01 am | Permalink
  16. Malcolm says

    The tree-trunk behavior does quiet the sound, which is consistent with my original hypothesis…

    Posted November 19, 2009 at 1:02 am | Permalink
  17. wisp says

    Very true, Malcom… Some recycling of urine would render my hypothesis much more believable…

    I’ve read that we have it, but i don’t trust my source.

    It’s also possible that we once had it and we lost it before losing this lingering response to water.

    I’m still seduced by the simplicity of my hypothesis…

    Posted November 28, 2009 at 3:19 am | Permalink
  18. Malcolm says

    Yes, Wisp, I liked it too. I think my objection is a fatal one, though.

    Posted November 28, 2009 at 2:40 pm | Permalink
  19. wisp says

    I got two predictions from my model.

    If it’s right, you should also feel a similar urge to urinate if you SEE water, and if you DRINK water.

    There’s a limitation to the first one, though. Running water is healthier than still water (sorry, i don’t know what you call it, English isn’t my native language). So seeing RUNNING water could make a difference.

    The whole effect could be less than hearing water anyway (because it sounds easier for Evolution to carve a neural path that relates to the SOUND of running water than its SIGHT, which would require a more complex set of parameters).

    My hypothesis could be saved even if we can’t recycle urine in any way if:
    a) We could do it in a distant past.
    b) It’s good to make room in the bladder for new urine.

    But why do we keep urine in the bladder anyway?

    Well, why do we? Why don’t we pee in little amounts all the time?

    Even if i was right, there are some elements clearly missing from the equation.

    Posted December 4, 2009 at 1:15 am | Permalink
  20. wisp says

    By the way, i don’t buy my own a). Hahaha!

    I know other animals feel this same urge too (i’ve read that you can make a horse urinate if you make it hear running water, although i don’t know why you’d want to do that).

    Posted December 4, 2009 at 1:17 am | Permalink