The article "
How evolution shapes the geometries of life: Scientists solve a longstanding biological puzzle" at
http://phys.org/news/2014-02-evoluti...gstanding.html posits that an apparent inconsistency in Kleiber's Law between plants and animals has been explained and that this 'missing element' in Kleiber's Law is an illustration of the convergent evolution of plants and animals to arrive at a common solution to the problem of maximum energy efficiency.
Quoting in summary, "Seeing this formula (Kleiber's Law) as a mathematical expression of an evolutionary fact, the team suggests that plants' and animals’ widely different forms evolved in parallel, as ideal ways to solve the problem of how to use energy efficiently. This formula, one of the few widely held tenets in biology, shows that as living things get larger, their metabolisms and their life spans increase at predictable rates. But why does Kleiber's Law hold true? Generations of scientists have hunted unsuccessfully for a simple, convincing explanation. In this new paper, the researchers propose that the shapes of both plants and animals evolved in response to the same mathematical and physical principles. "Plant and animal geometries have evolved more or less in parallel," said UMD botanist Todd Cooke. "The tree's nutrients flow at a constant speed, regardless of its size." With these variables, the team calculated the relationship between the mass of different tree species and their metabolisms, and found that the relationship conformed to Kleiber's Law.
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. So as animals get larger in size, their metabolism must increase at a slower rate than their volume, or they would not be able to get rid of the excess heat. If the surface area were the only thing that mattered, an animal's metabolism would increase as its size increased, at the rate of its mass to the two-thirds power. But Kleiber's Law, backed by many sets of observations, says the actual rate is mass to the three-quarters power. Clearly there's a missing factor, and scientists have pored over the data in an attempt to find out what it is. The UMD and University of Padua researchers argue a crucial variable has been overlooked: the speed at which nutrients are carried throughout the animals' bodies and heat is carried away. So the team members calculated the rate at which animals' hearts pump blood and found that the velocity of blood flow was equal to the animals' mass to the one-twelfth power. "Animals need to adjust the flow of nutrients and heat as their mass changes to maintain the greatest possible energy efficiency. That is why animals need a pump – a heart – and trees do not." Plugging that information into their equation, the researchers found they had attained a complete explanation for Kleiber's Law. You have these two lineages, plants and animals, that are very different and they arrive at the same conclusion. That is what's called convergent evolution, and the stunning result is that it's being driven by the underlying physics and the underlying math."
Some people may see this as supporting the Theory of Evolution, but I see it as an illustration of Intelligent Design by our Creator.