Re: what exactly do anthropologists do?
Thomas Kavanagh (tkavanag@indiana.edu)
11 Jul 1995 14:35:17 GMT
Just a quick note to clarify some language.
Some time ago, Gerold Firl <geroldf@sdd.hp.com> wrote:
<snip> ... all animals have a "built-in energy-expenditure-minimization
>function". If you've ever walked in the wilderness, you will have passed
>the trails used by animals. You might have noticed that they take the route
>which allows them to travel with minimal energy expenditure. For every
>motion we make, there is a large number of different muscle-activation
>sequences which could be used to execute that motion. We use the most
>energy-efficient one.
>
The problem is that "efficiency" is a relative term and must be seen in
relation with its converse, "power." Ecologist Howard Odum ("Time's
Speed Regulator") posits the relationship between "efficiency" and
"power" as complementary modes of action/adaptation that exist in time.
The two are related as the the ratio of energy expended to energy
available. That is,
energy expended
efficiency=--------------- (time) <1
energy available
and
energy expended = efficiency X energy available (time) <1
[that is "power"]
Firl is correct that an efficient ratio is one in which the least amount
of energy ("minimal energy expenditure") is expended doing a particular
activity. However, "least amount" is relative, and depends upon other
factors in the environment, including relative position in the ecosystem,
competition, and environmental stability and predictablility. In a stable
and more or less predictable environment, say a climax forest, the top
level trees are very efficient, and their metabolic and reproductive
rates are very slow, but conversely their available "power" is also slow
to act: a new oak seedling in a sunny patch left from the fall of an old
tree [an unstable and unpredictable environment] has a tough time
competing with weeds whose metabolic and reproductive power is much
greater, but which must flower and seed very quickly. But once
established the tree will literally overshadow (over power) those weeds.
A single species can go through both modes; for 16 1/2 years, 17 year
locusts have an extremely efficient metabolism; for a few weeks, they go
on a power rampage. But to keep up that rate, they will need an ever-
expanding resource.
There are some very interesting applications of this model to human
populations (see David E. Stuart, Prehistoric New Mexico, Background for
Survey).
tk
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