Allen and Gloger

I recently discovered an interesting little biological byline. I take a certainly delight in the rare occasions where trash talk forms a logical nexus with 'respectable' scientific theory. This little observation fell so neatly into that category that it had to get a mention, irrespective of the fears that it might impede the high-brow tone of this publication (*cough*).

It turns out that way back in 1877 a biologist named Joel Asaph Allen posited that endotherms in colder climates should have shorter appendages than equivalent animals from warmer climates. It became known as "Allen's rule".

The initial theory was framed in terms of the hypothesis that figures with more contrast between their dimensions have a greater surface area than figures with the same volume but closely comparable dimensions. That is, a rectangle with dimensions 4x1x2 has a greater surface area (28) than a cube with the same volume (a 2x2x2 cube has surface are of 24). More surface area means more heat loss, which is an advantage in hot climates, but a disadvantage in cold climates.

Examples of this include things like polar bears having short legs and recent studies suggesting that the hotter the climate, the larger the beaks on local birds.

There is another rule called "Gloger's rule" that states that within a species of endotherms, more pigmented forms tend to be found in regions closer to the equator.

I'm sure you can see where all of this biology is headed. All I'm saying is that that if you're walking past the science labs and you hear a girl in a lab coat tell her mate that she "went on a date with a gentleman of equatorial ancestry conforming to Gloger's rule" and subsequently "discovered he was a classic illustration of Allen's rule", you should get what those crazy science chicks are on about.