by Ezra Ownse 
In recent decades, there has been increasing indignation over 
the extirpation of wildlife species of this planet. Beyond 
this, the past decade has brought anxieties about species 
presently still short of extinction, yet in low and declining 
numbers -- those I have referred to in rhyme as tottering on 
the brink of doom. Today it is becoming more apparent that 
we must stop the slide of these declining species at an earlier 
stage. Protecting the last dozen or so individuals of a species 
may be too little, too late. It now appears -- at least in some 
animals -- that there is a numerical threshold below which re- 
covery of the species is unlikely, or indeed impossible. 
Most appeals for the protection of threatened animals have been 
emotional. They are entreaties aimed at public sensitivities 
rather than the public brain. Until recently, I had seen only 
two appeals for species preservation that had any defensible 
scientific elements in their plea. One of these concerns 
predator-prey relationships . The wolf pack and the cougar keep 
the prey herds healthy, since they remove mostly the halt and 
the lame. I fear, however, that despite its biological efficacy, 
this thesis falls short of conviction when one prey species is 
the deer hunter's target and the other the sheepman's livelihood. 
We need a still stronger scientific argument for preservation of 
these rare animals. 
Similarly, the public hasn't responded en masse to the proposal 
that some contact with the natural world (with its plant and 
animal life a significant segment) is conducive to the physical 
and emotional health of mankind. Psychological studies by the 
Cornell University Medical School indicate that one fifth of the 
inhabitants of midtown Manhattan are emotionally or mentally 
unstable to the degree that they were indistinguishable from 
patients in a mental hospital. Further, an additional 60% 
showed some lesser degree of mental instability -- only 20% 
Showed no symptoms of mental disease! The public has not related 
this to overcrowding in an artificial environment even though 
this type of aberrant behavior is abundantly documented in 
experimental studies of lower animals. 
What we: need, it seems to me, is a new, totally-confuting 
argument -- an unemotional appeal, a scientific law -- that 
indicates that a decrease in the number of species introduces a 
greater instability into the community. I have hopes that the 
Theory of Diversity will prove to be that biological law which 
Shows irrefutably that the loss of any species makes this world 
a little poorer. Here would be a piece of knowledge which would 
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