[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Allometric scaling laws

I just finished reading the paper by West, Brown, and Enquist in the 4
April 1997 issue of of Science concerning the origin of allometric
scaling laws.  While I found it fascinating, I did hae some problems
with it and a question as well.

They assume for their hypothesis that all terminal branches are
nonvariant in size.  Is this really true?  Are all capillaries in all
animals, as an example, really the same size no matter the size or type
of animal?

They claim that the circualatory system is "area-preserving."  This is
not accurate.  Not only are the walls elastic but the elasticity and
diameter of the tubes are under control of the animal and thus vary, not
only under different conditions but differently in various parts of the

They also claim that turbulence is a minor enough quantity that it can
be ignored for the most part and they try to deal with flow as being
laminar.  Not only is turbulence not minor, it dominates the flow of the
blood system, but laminar flow can not be used to readily describe blood
flow.  Hell, it works poorly to describe water flow in rigid smooth

These people are not idiots and I think I can safely assume that the
reviewers were not idiots, so can someone please give me some
explanations for these problems?

Joe Daniel