Physicists often simplify or idealize phenomena to make them more amenable to an initial mathematical treatment. We jokingly refer to this as considering a “spherical cow”. Sometimes one can understand even very subtle phenomena using this technique. However, there are always important effects that one needs the full, non-symmetric nature of the situation to understand.
Here, from The Telegraph, is an example of experimental data illustrating just this point (emphasis mine)!
Dr Sabine Begall and colleagues from the University of Duisburg-Essen looked at thousands of images of cattle on Google Earth in Britain, Ireland, India and the USA. They also studied 3,000 deer in the Czech Republic. The deer tended to face north when resting or grazing.
Although, in many cases, the images were not clear enough to determine which way the cattle were facing they were aligned on a north/south axis.
The scientists concluded that they were behaving in the same way as the deer.
Huge variations in the wind direction and sunlight in the areas where the beasts were found meant that the scientists were able to rule out those factors as being responsible for the direction they were facing.
“We conclude that the magnetic field is the only common and most likely factor responsible for the observed alignment,” the scientists wrote in an article published in the Proceedings of the National Academy of Sciences journal.
All joking aside, I found this fascinating. It is hard to see why this feature would be useful to cows these days, but if you accept the evil theory of evolution, things become a lot clearer.
Their innate ability to find north is believed to be a relic from the days when their wild ancestors needed an accurate sense of direction to migrate across the plains of Africa, Asia and Europe.
August 26th, 2008 at 2:06 pm
To test the theory they’ll need to put magnets on thousands of cows and see if it affects how they orient themselves. It was a great story.
August 26th, 2008 at 2:15 pm
Couldn’t it be something more mundane like: they face North so the sun is never in their eyes? All the countries they studied are in the Northern Hemisphere…
August 26th, 2008 at 2:41 pm
I dunno… even if cows had an internal compass to help them navigate while on the move, that doesn’t explain why they would stand facing north while grazing. My first intuition is that a north/south orientation maximizes the heat they get from the sun – their broad sides are always facing the direction of the sun. That wouldn’t explain why they choose north specifically rather than either north or south, but as you have pointed out, they don’t KNOW that the cows were facing north specifically, and the deer only “tended” to face north. How strong is the tendency, I wonder?
I love the title of this post. I used to describe undergrad physics as “where cows are spheres, spheres are points, and friction can always be ignored.”
August 26th, 2008 at 2:44 pm
Also, I wonder if they accounted for the time of day. Perhaps the deer and cows face north in the morning, and south in the afternoon (or vice versa) because of some internal asymmetry – for example they want to heat their hearts, which are further left.
August 26th, 2008 at 2:54 pm
To be fair, the dipole term is probably enough here….
August 26th, 2008 at 3:29 pm
I believe the technical term is Spontaneously Non-Spherical Cows (a.k.a. cows).
P.S. Moo!
August 26th, 2008 at 3:51 pm
Actually… Anyone know if they’re still putting magnets in cows? ie the canonical “cow magnet” seen in freshman EM courses? There seem to be plenty of websites still selling them for use as a cow magnet.
Not having a gauss meter, nor a cow magnet handy, and only my memory to work off of…. It seems like depending upon the orientation of the magnet you might get at least 1-10 gauss within 5.-1 meters of the magnet (that’s a guess, I should really look up a real starting point and make an estimate, but sigh…) Since the strength of the earth’s field is usually around 1/2 a gauss… do cows with magnets align to their own field from within their stomachs?
Or to put it another way… if the cows have magnets that are randomly oriented inside them producing fields comparable (or potentially much larger) to the “sense organ”, then how can they align to the earth’s field?
Michael
August 26th, 2008 at 5:13 pm
Is there a B-mode detection in the cow polarization field?
August 26th, 2008 at 6:30 pm
succinct version: “When we assumed that all equivocal data supported our hypothesis, support was found.”
August 26th, 2008 at 7:37 pm
“Couldn’t’t it be something more mundane like: they face North so the sun is never in their eyes?”
“My first intuition is that a north/south orientation maximizes the heat they get from the sun . . .”
“if the cows have magnets that are randomly oriented inside them producing fields comparable (or potentially much larger) to the “sense organ”, then how can they align to the earth’s field?”
So, attach magnets to the cows and see if it affects how they orient themselves. If it does have a statistically significant impact, then at least we know that maganetism may well have something to do with the original hypothesis.
August 26th, 2008 at 7:39 pm
“The deer tended to”, “huge variations”. What is this, liberal arts? We’re scientists, were is the statistical data?
August 26th, 2008 at 7:45 pm
The magnets may interfere with the cows’ directional ability but they’ll double their gas milage.
August 26th, 2008 at 9:41 pm
National Geographic is reporting this also
http://news.nationalgeographic.com/news/2008/08/080825-magnetic-cows.html?source=rss
Also http://www.physorg.com/news138902073.html
Some relevant quotes:
“The magnetic field of the Earth has to be considered as a factor,” the scientists said.
Two-thirds is close to what the researchers found in their look at 8,510 cattle in 308 pastures. In the study, 60 percent to 70 percent of cattle were oriented north-south, which Begall termed a “highly significant deviation from random distribution.”
Hinchley stressed that one factor that must be considered is cow comfort.
“They don’t like to get hot. Their body temperature is 102, and they are wearing black leather jackets, literally! If turning north-south would keep them cooler, they would stand that way.”
The research team noted that in very windy conditions cattle tend to face the wind, and have been known to seek out the sun on cold days. But they said they were able to discount weather effects in the study by analyzing clues such as the position of the sun based on shadows.
It would be interesting if it were true but I am still very skeptical.
August 26th, 2008 at 9:47 pm
Guys – its a (not particularly good) newspaper article about a study, not the study itself.
August 26th, 2008 at 9:54 pm
I had heard the term “spherical cows” before but I could not place it. On a quick search I found this below
[1] Harte, John (1988), Consider a Spherical Cow: A Course in Environmental Problem Solving, University Science Books, ISBN 978-0935702583
August 26th, 2008 at 9:56 pm
If the cows are spheres, how were they able to determine any orientation?
August 26th, 2008 at 10:00 pm
The article is supposed to be a joke on the methods used?
August 26th, 2008 at 10:48 pm
Yeah, I doubt 3000 pictures from Google Earth makes for a reliable sample space for observation. As was suggested, a lab controlled test is in order.
THe body heat hypothesis has more weight to it.
August 26th, 2008 at 10:54 pm
I like Kenneth Finnegan’s guess about not wanting the sun in the eyes the best… a most plausible alternative anyway…
also, while 60 to 70 % north south facing is interesting, it’s not as chilling a frequency as say 80 to 90 % would be…
still… it’s not unheard of in other farm animals…
http://www.eurekalert.org/pub_releases/2007-07/jwgf-cao070507.php
and the fact that this sort of number crunching on grass munching creatures exists at all is very cool…
-j-
August 26th, 2008 at 10:55 pm
-JR
It’s the spin of the spherical cow that determines orientation…
August 27th, 2008 at 2:33 am
In case I missed somebody else giving a pointer to the study itself, here you go.
Sabine Begall et al. (25 August 2008) “Magnetic alignment in grazing and resting cattle and deer” PNAS direct submission.
August 27th, 2008 at 2:39 am
I’m not so sure about the “sun in the eyes” idea. Remember that cows have eyes on the sides of their heads. They’d have to have their backs pointing almost directly at the Sun to not have it in their eyes, which would make sense, but would also be easily detectable from an analysis of the satellite imagery, as it would be possible to measure a difference in orientation between morning and afternoon. So, I don’t know. Maybe, but it doesn’t require any new observations to check. So it would somewhat surprise me if it hasn’t already been checked.
August 27th, 2008 at 9:12 am
If one has a particular bend toward their research perspective one might from this angle with regard to the New Scientist article think it is indeed a joke?
August 27th, 2008 at 9:20 am
i read in one blurb about this study that the cows didn’t just face north, they faced *magnetic north*, which varies depending on where the cows are.
i wonder if you can use a cow to attach things to your refrigerator?
August 27th, 2008 at 11:44 am
Magnetic North deviates from True North (by about 12 degrees in Montana) so you would think that if there *were* any magnetic effect, it would show as a bias from True North, increasing as you travel up through Canada.
Unless they are simply aligning with the local power grid or fenceline. Birds align as part of their flocking behavior, herds may have a migratory directional sense.
August 27th, 2008 at 11:44 am
When the magnets are switched on at LHC, do nearby cows wander across the landscape, or give milk which is better for making string cheese?
August 27th, 2008 at 2:03 pm
Actually, seems to me this demonstrates one of the weaknesses of evolution, the fact that it can stretched to support non-quantitative “just so stories”, to explain pretty much any fact (or its converse). I can certainly think about a few stories, at the same level of detail, explaining the cows aligning in the east-west direction, or in no direction at all.
August 27th, 2008 at 2:04 pm
My sister is a cowherd (I kid you not) and she shared my intuition that cows tend to stand with their arse to the wind.
The sun hypothesis only works if all aerial photographs are taken within a few hours of noon. Does anyone know if that’s the case?
But of course the next step is to find a goodish number of freerange farms, put up some webcams and equip the cattle the strong magnets (cowmagnets would indeed prolly be enough, but they’d prolly have to be fitted externally is the experiment is to last long enough to reach statistical significance).
I’m looking forward to the next batch of results.
August 27th, 2008 at 4:36 pm
I don’t think you can rule out the linear nature of their food as a contributing factor
August 27th, 2008 at 4:57 pm
In the orignal report on this story as reported around the world, the explanation is given as being ” parsimonious”.
No one apparently noticed this crucial fact. The word really means stingy with money. Nothing to do with cows or magnetism. Maybe this misuse of english is a clue that the whole story is a prank on the scientific world.
August 27th, 2008 at 5:37 pm
Alex,
Maybe so – but I looked at photographs of cows I took – and they were all pretty much facing either north or south; to my surprise mostly north – The cattle farmer said they lie any which way there is room.
August 27th, 2008 at 6:09 pm
“Parsimonious” refers to the grant committee. It’s a subtle hint reminding them that only a little more money would have produced much more compelling results. Unfortunately grant committees are completely deaf to subtlety.
August 27th, 2008 at 6:14 pm
Alex,
“parsimonious” with the meaning of “using as few resources as remotely possible” (although often applied to money) is frequently used in learning theory. Saying an explanation is parsimonious is basically applying Occam’s razor with mentioning competing more complicated theories.
The big thing here is that a paper that’s an interesting quick-and-dirty experiment’s write-up, which might be followed up with more monetarily expensive equipment if a grant could be obtained, has been picked up by all sorts of general media and presented so that it seems like a bold, definitive statement.
August 27th, 2008 at 6:15 pm
Ugh, that should be “Saying an explanation is parsimonious is basically applying Occam’s razor without mentioning any competing more complicated theories.”
August 27th, 2008 at 6:29 pm
I have always wondered why it is that cows grazing under power lines oscillate 60 times per second…
August 28th, 2008 at 1:16 am
No one has mentioned predators… What are the wolves doing? A deer’s number one concern – above grazing, above body heat, above migration, and way above sun in his eyes, is avoiding wolves. Predators will attack from downwind, so as not to be detected. I have also heard that they will minimize their silhouette when standing on a hill (no idea if this is actually true). What other tactics could predators be using related to sun position or magnetic direction that the cows and deer could be watching or smelling for?
The problem with that theory is that cows don’t really have to worry about wolves. Any anti-predator behaviour would have been artificially bred out long ago. Then again, so would migratory behaviour, as they don’t have to worry about that either. What possible selection pressures do cows currently face, that they share with deer, that could explain the orientation?
August 28th, 2008 at 3:16 am
I agree with Mark. Truly this is a news paper article about a study .I love the title of this post.
August 28th, 2008 at 7:17 am
“My sister is a cowherd (I kid you not) and she shared my intuition that cows tend to stand with their arse to the wind.”
As cows don’t use loo paper, maybe another advantage for them in standing with backs to the sun and/or wind is that this will tend to dry their hindquarters quickest. Also the sun’s UV radiation will help sterilize any mess round the cow’s tail, and maybe even dry out and kill parasite eggs laid by things like flies.
August 28th, 2008 at 12:24 pm
At last, we can do perturbation analysis as a function of the radius of spherical cows, in our grazing/search for the Unified Field Theory (original meaning of “field”).
August 17, 2008
Just right for the garden: a mini-cow
Miniature cattle farming is catching on with families trying to stay ahead of rising food prices
Chris Gourlay
It’s the little cow with a big future. Rising supermarket prices are persuading hundreds of families to turn their back gardens into mini-ranches stocked with miniature cattle.
Registrations of the most popular breed, the Dexter, have doubled since the millennium and websites are sprouting up offering “the world’s most efficient, cutest and tastiest cows”.
For between £200 and £2,000, people can buy a cow that stands no taller than a large German shepherd dog, gives 16 pints of milk a day that can be drunk unpasteurised, keeps the grass “mown” and will be a family pet for years before ending up in the freezer. …
August 29th, 2008 at 3:37 pm
Its time to study the direction the grasses and forbs are leaning, likely towards the sun. If that is towards the south, the yummy seed heads would be easier to get at while facing north.
August 31st, 2008 at 2:08 pm
As the greatest intellectual danger a cow can suffer is the terrible North wind of blizzards, I can’t be much confused. We know that humans are made ‘special’ to think, with all other many legged things not quite so effortful at intelligent behavior….lets see…
The greatest mass exposure for warming in the comfort weather would be N/S or S/N, with the head to North in the low angle sun of the cold winter, still the better statistical preference, while habituated from the bad weather periods.
In the high summer, the North facing animal still avoids the sun on the head preferentially.
I have always believed this process was at fault for weakening the survival skills of the Dinosaur types of the past- a migration process gone bad statistically, additional to other reasons. It is claimed that many dinosaurs commonly used the head and nasal passages for cooling mechanisms, requiring they be facing the North preferentially during the year, or alternating E/W during the days travel path,avoiding the sun angle, in a reversal of paths without gain during weather stress.
Now, am I thinking just like a cow, or not?
http://www.cowswithguns.com/homepage.html
site included as a link at top to quell the stressed humans, as again, they are sure the ‘other’ group has the upper hand intellectually, and we must therefore dwell on the natural.
Why do humans prefer north facing homes? Cool idea, or not?
My real thinking here:
http://www.marsroverblog.com/forum.html
August 31st, 2008 at 2:28 pm
I would like to defend my supposition with one additional observation, as the details are accumulative when an argument is finalized. Humans use the same technique to dress themselves, warming the backsides greater than the front, as a sign of polarity in coping. Not non-symmetric, axial, as would be expected of most tetra-pods.
-:–:–
September 2nd, 2008 at 9:14 am
This may be the right occasion to reexamine the navigational practices of the Vikings. Perhaps the etymology of L’Anse aux Meadows really should reference fields of grass instead of jellyfish, since clearly the Vikings were seeking fodder for their quadrupedal compasses when they landed in Newfoundland.