Physics.org has put up a new article on expansion to Kleiber's Law

http://phys.org/news/2014-02-evolution-geometries-life-scientists-longstanding.html

Interesting if somewhat controversial

So far I have only skimmed through the article, so this comment may not be justified.

“To nourish its mass, an animal needs fuel. Burning that fuel generates heat. The animal has to find a way to get rid of excess body heat. The obvious way is surface cooling. But because the tiger's surface area is proportionally smaller than its mass, the surface is not up to the task. The creature's hide would get blazing hot, and its coat might burst into flames.”

Isn't the prevention of this part of the function of the respiratory system?

In a way this explanation sort of makes sense. I can see that Natural Selection would tend to direct life into forms that in one way or another are energy efficient. Being energy efficient means that the life form can live, and have children, with as little food intake as possible. So a life form that is less energy efficient would tend to have fewer offspring. Therefore low energy efficiency would tend to be selected out. The result would be that most life forms would evolve to be as energy efficient as possible. There would have to be a balance between energy efficiency and the activities that gather the energy. I could see that there might be a sort of a balance point there that would turn out to be the same for all life forms.

It does seem to me that if a life form develops some characteristic that is less energy efficient, but confers some other positive benefit it may still be selected. I'm not sure just what that would entail. It's possible that this would produce a brief surge in the species which would then be worked out to restore the 'normal' energy efficiency.

Bill, How the tiger loses the excess heat isn't really what they are talking about. They are addressing the overall energy balance of whatever life form they study.

Bill Gill