422 THE FUTURE OF ARID LANDS 
emphasize the following points, which I feel should be clearly 
established. 
1. Arid zones offer intrinsic conditions which necessitate the 
greatest caution in considering any project affecting them. 
2. The rise in local living standards should not depend exclu- 
sively on the improvement of domestic animals and plants nor 
on the introduction of new ones; it should also be based, as far 
as possible, on the rational ecological utilization of the elements 
native to the region. 
3. Any tendency to a substantial increase in the population 
should be carefully examined before encouraging it, for it could 
have disastrous results. As Bailey states so well in the words 
which preface these comments, the margin of tolerance in arid 
regions is so small that any error may have fatal consequences. 
By always bearing in mind the existence of the arid zone-wild 
plants and animals-human population-domestic plants and animals 
complex, one may get a general view of the problems relative to 
the improvement of those regions. In order to ensure permanent 
yields, it is essential to base any action onsound ecological grounds, 
with a clear conservationist orientation. 
Perhaps the preceding observations may appear pessimistic, 
although in reality they are not. Basically, they tend to guarantee 
a high living standard to the desert population groups by yre- 
venting the feeble environment which supports them from further 
deterioration as the result of an intensive misguided exploitation 
producing only temporarily favorable yields. 
Nor do we state categorically that an increase in the human 
population of those zones is impossible. We only point out the 
obvious potential danger, that an immoderate increase in popula- 
tion may provoke a real catastrophe in a naturally adverse en- 
vironment. 
If we accept, and we believe it is impossible not to do so, the 
existence of the arid zone-wild plants and animals-human popula- 
tion-domestic plants and animals complex, it is evident that it will 
be necessary to seek a reasonable ecological equilibrium among 
those four components. Any omission of one of these, or the mis- 
