Kleiber’s Law states that (basal) metabolism varies as a 3/4 power of mass. It is based on the researches of Max Kleiber who studied animal physiology. It probably first appeared in an article he wrote in 1932. Kleiber’s Law is an empirical observation. It has somewhat, but not entirely, superseded the surface law which supposes that metabolism varies as a 2/3 power of mass. The original theoretical justification for a surface law was made by Sarrus and Rameaux in 1838. (I have posted an English translation of their 1838 work on RG, appended to which is a copy of the original report on their work.) In 1997 West Brown and Enquist (WBE 1997) described a geometrical explanation accounting for Kleiber’s 3/4 power scaling. Kozlowski and Kornazewski in 2004 and 2005, among others, described apparent inconsistencies in WBE 1997. WBE 1997 begins by observing that biological diversity varies `over 21 orders of magnitude’. This observation suggests one possible aspect of Kleiber’s Law. If Kleiber’s Law varies over a comparable number of orders of magnitude it may be because Kleiber’s Law is a manifestation of a universal scale invariant law that applies generally, not just to organisms. It is apparent that no such law has yet been detected by physics because if it had it would have been used already to explain metabolic scaling. For these and other reasons, Kleiber’s Law may be important not just for biology but for physics generally. What do you think?
of course it is important.. Kleiber' law is one of the most important and best-known laws in bioenergetics ..
It is useful as a description of how certain indicators change with size. However, it doesn't explain why the BMR follows the rule. Or why adults and children fit different data. A few decades I modeled BMR as a function of body composition, using Kleibers data for adults and children ... but very specific variables as determinants. Across growth and aging, three elements of body composition contribute to BMR.
(a) High metabolizing tissues [brain & endocrine];
(c) low metabolizing [bone, connective tissue, adipose tissue];
(b) middling metabolism [at rest "BASAL", muscle, spleen, liver, etc].
During growth, the most important out to be, of course, brain size [1] I used data on how brain size changes (diminishing as a fraction of body weight) from 45% at birth during growth; [2] In maturity brain is constant at around 1.4kg while muscle mass depends of lifestyle; [3] In old age water % decreases & on average adipose t replaces muscle. Once I estimated these from data in the literature, if fitted the data for BMR as a function of size, right from BIRTH to old age. Across all of Kleiber's data across adults AND children; males & females! Kleiber had to use different coefficients where body composition fits all sizes, shapes, genders, age perfectly.
I should have published it, but my interests moved on. If anyone would like to revisit this old puzzle - the functional determinants of BMR as a function of growth to birth, I'll send you the data. allanjdavison @ sfu.ca