Monday, 25 August 2008

Cows... with Magnets!

Now here's a headline to set off a healthy bit of scepticism:

"Cattle shown to align north-south"

I'm not going to rubbish that claim straight off the bat, but I'd definitely need a little more proof than a few anecdotes and images before thinking there was something to it. Why would they do that? I'm well aware that a sense of magnetic direction is seemingly quite a widespread phenomenon among Terran fauna, but I have a hard time understanding why this particular ability would be of any use to cattle.

Over eight and a half thousand images of cattle were examined, apparently. That's a pretty good sample size, I'd say; but nowhere do I see the numbers involved in working out the incidence of north-south alignment (if anyone can grab access to the actual article, I'd be grateful for a link).

A couple of other points stood out for me in the BBC report of this: firstly, that in Africa and South America, the scientists carrying out the study noted a north-east/south-west alignment rather than the north-south seen elsewhere; they explain this by pointing out that the magnetic field is weaker there. OK, granted. But why then are they still aligning along a different line? Without seeing the data itself, that sounds to me like whatever method they used to determine significant alignment might be a little too generous.

Secondly comes the speculation of reasons why this north-south alignment might be happening; the lead scientist is quoted as speculating that it could be anti-predatory behaviour.

I'm sorry, what?

Do most predators come from the north or south? Would it not be a more effective technique to have the herd facing in different directions if it's an alert system you're looking for? I can appreciate the use in having the herd facing the same direction - if the need to flee arises, it makes that safety-in-numbers thing much easier to manage. This would seem to be the most reasonable explanation for a herd facing in generally the same direction as each other. But if this is the case, why north-south? Perhaps they just like facing south; perhaps it feels like going downhill...

Basically this sounds like fluff reporting of a half-baked investigation. I'd like to see the numbers involved, but at the moment I remain unconvinced that there is a phenomenon to explain here; I'll agree that in general a herd will face in more or less the same direction. That much is hardly news. The north-south thing, though? Needs a little more work.


EDIT: The story has been taken up by Ed at Not Exactly Rocket Science, and it seems that he's read the article! Here's his take on it. Reading through, it seems like those numbers I was after do actually add up quite nicely; as for the reason behind it, the general notion seems to be that they have as much reason to line up in this way as a compass needle does. It's just what they do. Some intriguing ideas are being thrown around about physiological processes running smoother when aligned with the poles, but these are still at the hypothesis stage.

I wouldn't be much of a sceptic if I didn't change my tune when faced with the numbers. I still maintain my opinion of the original piece on the BBC, though. The quality of science reporting is, as I should have come to expect by now, somewhat south (haha) of optimal.

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