>Larger organisms don't need to generate as much heat as smaller ones, because heat dissipation occurs across surface area, which increases as the square of mass, whereas heat generation increases as the cube (assuming a spherical cow, but close enough.)
Except that hypothesis doesn't predict the correct exponent. If that were the reason metabolic power would scale as mass^(2/3), but it actually scales as mass^(3/4).
>the mitochondria of a human are not that different from those of a rat, or even an earthworm.
West is acutely aware of this. In the talk I linked above he describes biological lifespans in terms of the relationship between the energy required to synthesize ATP and kT (ie the Boltzmann constant times ambient temperature, being the average energy of a particle due to random thermal motion).
The trick is in explaining quantitatively why those universal biological facts scale over size and time with the sometimes bizarre scaling factors observed. It does boil down to physics of course, but there's a lot more to it than just heat dissipation.
That's a fair point-- a naive hypothesis based only on heat dissipation won't predict the correct exponent. My criticism was basically mostly about the lack of citations in the article to all the earlier people who have thought about these problems, as well as the idea that finding patterns in biological or anthropological data was somehow new and revolutionary. Maybe the article snipped a lot of the context of Dr. West's own writings-- that would be typical for science journalism.
Except that hypothesis doesn't predict the correct exponent. If that were the reason metabolic power would scale as mass^(2/3), but it actually scales as mass^(3/4).
https://en.wikipedia.org/wiki/Kleiber's_law
West's space filling fractal hypothesis predicts dozens of non-obvious scaling laws, not just metabolic power. http://www.youtube.com/watch?v=DFFVSvAr7Wc
>the mitochondria of a human are not that different from those of a rat, or even an earthworm.
West is acutely aware of this. In the talk I linked above he describes biological lifespans in terms of the relationship between the energy required to synthesize ATP and kT (ie the Boltzmann constant times ambient temperature, being the average energy of a particle due to random thermal motion).
The trick is in explaining quantitatively why those universal biological facts scale over size and time with the sometimes bizarre scaling factors observed. It does boil down to physics of course, but there's a lot more to it than just heat dissipation.