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Re: Master Equation for all life processes?

The first thing that came to my mind, not knowing much about this, was to look at surface to volume ratio. Then I read the article and saw that was where it all started and still remains, but the surface they think is important is the blood vessles and other similar internal energy delivery devices.

It seems that reductive "discoveries" of a general tendency capture a lot of attention. As the quote in the article implied, we generally want the rule from which to measure the exceptions. Naturally it is valuable to know the basic physical constraints before adding the biology, and as the article points out we did not investigate how far these physical ratios reach as general constraints. However, what should be interesting in biology is not the physics, but the biology. The exceptions to basic physical scaling are more interesting for this reason.

As far as the primacy of metabolic rate in scaling other phenomena, I suppose we could expand that to metabolism and repair, but if repair operates at the same rate, it would be the same equation.

I have the feeling that there is something rather trivial about this grand theory. I suppose being able to predict tree spacing from tree size is useful if it isn't already obvious, and of course many other relations. But it is all about a basic physical constraint.

Does this ratio change with age after maturity? Why?

I would be interested to compare the psychological sense of time with metabolism, but I don't know how. I'd be looking for an exponential law in some range after correction for size and temperature.

John Kineman

Dan Fiscus wrote:

Steve,

This stuff has been around a long time. It does
intrigue me and I think it deeply important, but
the missing aspect to me is that Jim Brown,
Enquist, West and others who worked on this a lot
treat the scaling as if organisms all developed
these power law relations in isolation. In fact,
they all co-evolved and require an ecological
network for their context and inter-connected
webs of support, recycling, energy flow and
co-construction. The lynch pin I think is needed
and I have worked on it some is to integrate the
power law scalings of abiotic and semi-biotic
realms like C and N in soils. Now we have the
same scalings in three interdepenendent realms -
composers (autotrophs, metabolizers), decomposers
(heterotrophis, repairers) and soils (repair of
repair).

Some thoughts...

Dan



A story on Science News:


Science News recently wrote that some simple mathematical equations,
known as quarter-power scaling laws, can explain the metabolic rates of
living organisms. For example, "an animal's metabolic rate appears to be
proportional to mass to the 3/4 power." And this "3/4-power law appears
to hold sway from microbes to whales, creatures of sizes ranging over a
mind-boggling 21 orders of magnitude."

Here are full text links:

Ecology's big, hot idea:

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=535575

http://www.primidi.com/2005/02/21.html

http://www.sciencenews.org/articles/20050212/bob9.asp




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