460 PHYSIOLOGICAL EEGULATIONS 



Probably all equilibrations have undergone evolution. Whether 

 they evolved by selection, by orthogenesis, by mutation, by fore- 

 sight, or by all of them, can be imagined without much limitation by 

 fact. Believing that regulations are indispensable, I think some 

 are as old as any form of life. Since there is almost no paleon- 

 tology of function, one theory will be as plausible as another. I 

 would argue for polyphyletic origins, trial and selection of re- 

 sponses, and resourceful variations. 



If I were an animal without heat regulation I think I would try 

 keeping cool by acquiring stepwise some modest arrangements for 

 refrigeration. But I would not stake my water content very far 

 to do it, for, my ancestors had not. I would install a thermostatted 

 heater only after the cooler was working efficiently. At first I 

 would be content with a range of ± 20° C. in body temperature, later 

 of less and less until I got down to about ± 0.5° C. and then I would 

 lose interest in securing greater accuracy unless some other activity 

 began ''demanding" further refinement as an aid in accomplish- 

 ing its work. I would count a heater as economical only if with it I 

 could go places where fuel would be cheap enough to justify it ; my 

 ancestors had sat in the sun, or burrowed in the ground, or insulated 

 themselves instead. Actually I presume that I would have no 

 foresight sufficient to count the cost or to weigh the specific out- 

 come ; but maybe there is some subconscious way of inferring the 

 whole outcome from trials. Every added regulation would involve 

 a liability of having something go wrong, of requiring upkeep. 

 Perhaps that is why I do not fix carbon dioxide and then reduce it to 

 cool myself. Whether I could discover cheaper means of refriger- 

 ating or not would help to decide whether I would maintain 37° C. 

 or 27° C. Maybe I could experiment with that after I had the 

 machinery for both cooling and heating, finding which of the two 

 was "easier," and which upset my other components least. If I 

 stopped to picture all the ''optimal" velocities that would clamor 

 for recognition, I would never reach a decision. 



^Tiile I imagine I could have lived for millions of years without 

 doing very much to adjust my body temperature, by the subterfuge 

 of not going to places too hot or too cool, I would have little but 

 subterfuge at first to help govern my water content. But gradually 

 I would explore into ways of retarding my water losses, and of 

 repelling water ingress ; I would try to accomplish both at once. I 

 might then find some excuse for setting aside one area of my sur- 



