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“Dogs are sensitive to small variations of the Earth’s magnetic field”

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Two different people pointed me to this article by Vlastimil Hart et al. in the journal Frontiers in Zoology:

It is for the first time that (a) magnetic sensitivity was proved in dogs, (b) a measurable, predictable behavioral reaction upon natural MF fluctuations could be unambiguously proven in a mammal, and (c) high sensitivity to small changes in polarity, rather than in intensity, of MF was identified as biologically meaningful. Our findings open new horizons in magnetoreception research. Since the MF is calm in only about 20 % of the daylight period, our findings might provide an explanation why many magnetoreception experiments were hardly replicable and why directional values of records in diverse observations are frequently compromised by scatter.

Tom Passin writes:

Here we seem to have multiple comparisons and (to me, at least) dubious plausibility, together with a kind of fanciful topic and a large vaiety of plausible alternative explanations.

And another correspondent, who wishes to remain anonymous, writes:

I was curious as to whether you had ever had a blog post about one or more of Hynek Burda’s group’s papers on mammals aligning themselves to the Earth’s magnetic North-South for different activities: cows grazing, foxes hunting mice, and now dogs defecating.

The cows grazing paper appeared in PNAS in 2008. And there was some renewed debate about it a couple of years later when a second group was unable to reproduce it.

As for the research on dogs, I don’t think that I know anything about circular statistics and I probably know even less about the natural fluctuations in the Earth’s magnetic field. But I am skeptical of the conclusions. Anecdotally, the first time my dog pooped after I read this, he was facing due West.

I didn’t have the patience to read the article in detail—to be honest, I’m more of a cat person—but I agree that there do seem to be multiple comparisons issues, as can be seen from the Results section of the abstract:

Dogs preferred to excrete with the body being aligned along the North–south axis under calm MF conditions. This directional behavior was abolished under Unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF.

Also, this from the Discussion section:

The study was truly blind. Although the observers were acquainted with our previous studies on magnetic alignment in animals and could have consciously or unconsciously biased the results, no one, not even the coordinators of the study, hypothesized that expression of alignment could have been affected by the geomagnetic situation, and particularly by such subtle changes of the magnetic declination. The idea leading to the discovery of the correlation emerged after sampling was closed and the first statistical analyses (with rather negative results, cf. Figure 1) had been performed.

And this:

We found no differences in alignment of females and males during defecation and of females during urination . . .

And, speaking of chasing the noise:

Although intensity and declination changes are mostly concomitant, declination change was a better predictor of dog alignment. Interestingly, the rate and direction of the changes disturb more effectively than absolute values. . . . Our analysis of the raw data (not shown here) indicates that dogs not only prefer N-S direction, but at the same time they also avoid E-W direction. . . . Analysis of the alignment during defecation under conditions of stable magnetic declination (0 % changes) revealed no significant effect of sex. There may be a slight effect of age: dogs in the age category 2.5-7 years showed a clearer preference than younger or elder dogs (not shown). . . . Circular analysis of the distribution of the pooled raw data demonstrated a significant deviation from random distribution also in urinating dogs (Table 4). Analyzing this data for males and females separately we found a slight difference in the patterns between sexes . . . females showed an axial preference for approximately the North–south axis during urination (Table 7). As in the case of defecation, sorting the data according to the relative changes of declination revealed a significant effect of this factor and a significant axial North–south alignment only under calm MF conditions . . . The raw data distributions during changing declination were significantly differen distribution under calm magnetic conditions . . .

As always, I have no problem with this sort of exploratory analysis, I just don’t think the estimates and p-values can or should be taken literally in their raw unpooled states. If you want to stick with your available data, I think it makes sense to use multilevel modeling to resolve such multiple comparisons issues.

In this particular example, given the general (and, it seems to me) skepticism about these claims, I’d recommend a preregistered replication. And, really, news organizations should know better than to report such claims uncritically.

I wonder what Dr. Anil Potti would think of all this. I’m pretty sure that he could obtain a successful replication of this finding, if he really wanted to.

13 Comments

  1. jonathan says:

    The research on hammerhead sharks and magnetic fields is much more interesting.

  2. Ben Bolker says:

    Comment from “hamnaabobaker” is link spam (I thought I saw another one on another post here the other day, but I can’t find it again — maybe you cleaned it up).

  3. Phil says:

    There’s a belief, based on somewhat similar evidence, that when foxes hunt animals under the snow — the fox listens, then pounces — they are more successful when jumping north. Ah, yeah, here’s the study.

    I’m skeptical about both the dogs and the foxes. I can’t see how or why the dog behavior would have evolved…do we really think that a dog that faces a random direction when it poops is going to be less likely to reproduce successfully? Or that maybe sexual selection is at work, such that dogs that prefer to mate with north-facing poopers?

    As for the foxes, I’ve watched foxes hunt in the snow — it’s immensely entertaining and I recommend it to anyone, if you can find a fox — and they do not pursue a strategy that would lead to more northward jumps. If you’re a fox, all you’d have to do is start your patrol at the south end of the field and work your way northward, and although you will often hear (and pounce on) prey off to the sides, you will at least have more northward jumps than southward ones…and yet, both foxes I’ve been able to watch for long periods happened to be moving more or less southward rather than northward. If foxes were really much more successful when jumping northward than when jumping in other directions, I would expect them to exploit that fact.

    (By the way, in case you’re thinking “maybe dogs don’t like to poop with the sun in their eyes”, and something similar for why foxes would have higher success when jumping away from the sun: if you read the articles, the researchers claim that “true north” is magical at all times of day and in all weathers, so it’s not a sun-generated effect).

    I think these studies will eventually be debunked. The fox one seems slightly more plausible than the dog one.

    • Rahul says:

      Indeed.

      In any case, if they waited long enough and observed many enough dogs I’m sure a good data mining exercise could yield at least something like “First born female dogs between the age of 2.5 and 3.5 and 8 and 9.5 showed a slight preference for alignment during scratching their right ear when done between 1 pm and 9pm “

  4. Fernando says:

    As a gardener I am more of a plant guy: http://j.mp/1dyLC8Y

  5. John Mashey says:

    Well, given An Empirical Study of Some Astrological Factors in Relation to Dog Behaviour Differences by Statistical Analysis and Compared with Human Characteristics, if true, dogs might also know when they are facing magnetic North. :-)
    ‘Abstract-A survey of 500 pedigree dogs was carried out in the Paris region.
    For each dog, six behavioural traits were determined and ten of their astrological
    traits were retained. A statistical interpretation of the possible relationships
    between the two sets of traits was performed based on permutation tests.
    Two strong associations were detected between the angular positions of Jupiter
    and the Sun, and the extraversion dominant trait. There were indications of
    other associations. These associations have a remarkable resemblance to the
    standard associations usually proposed in “human” astrology.’

  6. Eli Rabett says:

    Again, for this sort of thing statistics is just not very impressive. Set up a square dog run and impose a constant magnetic field several times that of the earth. The other thing that screams is that the dip angle in the US and Europe is about 70 degrees so as far as direction goes the dogs should simply shit sitting …..wait, there is a paper there.

  7. […] and I bet there were a fair number of researcher degrees of freedom involved in the analysis. See here for similar concerns about a more recent, related study claiming that domestic dogs orient using the […]

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