Re: Uploaded memories

From: Robin Hanson (rhanson@gmu.edu)
Date: Wed Dec 08 1999 - 14:32:39 MST


Robert Bradbury wrote:
>You should read Science News Nov. 27 1999, pg 340-341 citing an article
>in Nov. 25, Nature by Jef Huisman and Franz J. Weissing who appear to
>have a mathematical rationale for why sub-fit species can survive
>and prosper. Its fundamentally wrapped up in the number of essential
>nutrients there are. The more nutrients there are the more species
>an environment can support, precisely because of the exponential
>growth problem. A species grows until it exhausts the supply of
>the essential nutrient it is best at harvesting, then another species
>that depends on different nutrients grows until that nutrient
>becomes limiting, etc.

I read that paper and liked it, but I think you misunderstand it.
It is not describing a sequence of species saturating one after another.

The paper was taking as a puzzle the fact that we tend to see a lot
more species than we see essential nutrients, even though a simple
model says that you shouldn't. They note that a fluctuating
environment is enough to make room for lots more kinds of species,
each one tuned to a different frequency of fluctuation. The
paper's contribution is to then note that if different species
approach equilibrium at different rates, that is enough to create
a fluctuating environment which can support many species.
You don't need outside fluctuations; inside ones are enough.

Robin Hanson rhanson@gmu.edu http://hanson.gmu.edu
Asst. Prof. Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323



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