THEVOICEOFTHEDESERT ^^ 



overgrazing the desert vegetation, in others slowly, be- 

 cause nature herself does not stand still. 



On the other hand, new as the desert is in terms of 

 geology and relatively new as it is in terms of its flora 

 and fauna, it is still very ancient from man's own stand- 

 point. It seems to be quite definitely established that In- 

 dians were aheady inhabiting some parts of the South- 

 west as much as ten thousand years ago, and if any of them 

 had aheady got to southern Arizona, they must have found 

 it not too unlike what it is today, though some of the 

 vegetation was probably less sparse. But "ten thousand 

 years ago" really is "today" so far as the story of evolution 

 is concerned. Long before that, European man had reached 

 a stage of mental development which made his skull 

 nearly identical with that of us moderns. Long before that 

 a road runner, scarcely if at all distinguishable from those 

 now rejoicing in the desert and dry coastal areas, had 

 fallen into the famous tar pits near Los Angeles where 

 its bones remained until they were dug up a few years ago. 



Since the cactus is even stranger as a plant than the road 

 runner is as a bird, it is perhaps of the cactus that we 

 had better ask, diffidently but more specifically, the ques- 

 tions proposed a few paragraphs back. "How and \yhen 

 did you get here? Where did you come from? What were 

 your ancestors like? By what stages did you adapt your- 

 self so admirably to the very special conditions you found 

 in the southwestern deserts?" 



At least a partial answer can be given to these ques- 

 tions, though the answers have to be based not on geo- 

 logical evidence but upon a study of the living members 

 of the cactus family. Some of them grow in regions only 



