Posts Tagged ‘theoretical biology’

There is an apocryphal story about a graduate mathematics student at the University of Virginia studying the properties of certain mathematical objects. In his fifth year some killjoy bastard elsewhere published a paper proving that there are no such mathematical objects. He dropped out of the program, and I never did hear where he is today. He’s probably making my cappuccino right now.

This week, a professor named Peter Sheridan Dodds published a new paper in Physical Review Letters further fleshing out a theory concerning why a 2/3 power law may apply for metabolic rate. The 2/3 law says that metabolic rate in animals rises as the 2/3 power of body mass.  It was in a 2001 Journal of Theoretical Biology paper that he first argued that perhaps a 2/3 law applies, and that paper — along with others such as the one that just appeared — is what has put him in the Killjoy Hall of Fame.  The University of Virginia’s killjoy was a mere amateur.

Peter Sheridan Dodds, Buzzkill

The 2/3 scaling law, you see, is intuitively obvious (even if not intuitively obvious to truly defend in detail). The surface area of animals scales as the 2/3 power of their body mass, and so the rate of heat loss scales as the 2/3 power. If metabolic rate scaled as the 2/3 power, few theorists would probably have bothered taking the problem on.

But in the 1930s one Max Kleiber accumulated data that suggested to him that metabolic rate scales as the 3/4 power of body mass. It came to be known as Kleiber’s Law. 3/4 is fun. …to a theorist. 2/3, however, is boring. 3/4 is so fun that theorists had a field day trying to explain it, and there was an especially gigantic spike in the fun starting from 1997, especially from a series of papers by West, Brown and Enquist, and also by Banavar and Maritan.

And that’s when buzzkill Dodds came along with his 2001 paper. He re-examined the data, and suggested that a 2/3 law could not be rejected. There may be no 3/4 law to explain after all. Nothing to see here, move along everyone. That paper further put salt in the wound by pointing out that one of the theories deriving the 3/4 law had an error.

Although Dodds is still at it with his current paper, to compensate for his party-downer laurels, he’s accumulated some of the most interesting research out there, from rivers to bodies to disease to the happiness of songs over time. (Thanks, Peter, for being a good sport.)

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

This first appeared on February 9, 2010, as a feature at ScientificBlogging.com.

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