viii I Preface 



feel to be rewarding and stimulating. It is, however, important that 

 it be recognized as speculation. In some areas, other evolutionists 

 certainly will find our treatment heterodox. In particular, we have 

 deemphasized taxonomic ideas such as species and subspecies, 

 which we feel have channeled the thinking of biologists about evo- 

 lutionary problems. The term adaptation has been given the rela- 

 tively inconspicuous role that we feel it deserves. Our reasons are 

 discussed in the final chapter. 



We have tried to make our descriptions and discussions as rigorous 

 as possible, except where it becomes absurdly pedantic to avoid 

 taxonomic concepts or the casual use of words such as selection 

 and adaptation. Lapses into what may be termed teleology we 

 regard as teleonomy. We hope the reader will agree that a some- 

 what more unified and logical treatment of evolutionary phenomena 

 is possible if a rigid taxonomic framework is not followed. Scientific 

 names used in this book connote kinds of organisms and carry no 

 implications of genetic attributes or phylogeny. 



At the end of each chapter is a list of references chosen, in part, 

 because of their currency and extensive bibliographies. Each ref- 

 erence is briefly annotated. Reference without a direct citation often 

 is made to scientists closely associated with a particular concept 

 or experiment; direct citations can be found in the bibliographies of 

 general papers listed. A rather extensive glossary also has been 

 included. 



Our intellectual indebtedness to a very large number of evolu- 

 tionists will be obvious. We must specifically acknowledge the writ- 

 ings of Edgar Anderson, C. D. Darlington, Theodosius Dobzhansky, 

 Herbert L. Mason, Ernst Mayr, George Gaylord Simpson, G. Led- 

 yard Stebbins, and Sewall Wright which have had a profound 

 influence in interesting us in evolutionary problems and in shaping 

 our thoughts about them. 



We should Hke to thank the following persons who have helped 

 us in many ways in the task of preparing this book: Joseph H. 

 Camin, Verne Grant, P. H. Greenwood, N. K. Johnson, Alan E. 

 Leviton, George S. Myers, C. L. Remington, R. G. Schmieder, and 

 Robert C. Stebbins. 



One or more chapters of the manuscript were read by Kenneth B. 

 Armitage, William K. Baker, D. L. Bilderback, Marsden S. Blois, 

 Winslow R. Briggs, Howell V. Daly, Ruth R. Ehrlich, M. M. Green, 

 Robert W. Hull, Joan Johnston, Donald Kennedy, Charles D. 

 Michener, Ashley Montagu, Robert M. Page, John F. Pelton, David 

 D. Perkins, Timothy Prout, Peter H. Raven, David C. Regnery, G. G. 

 Simpson, Robert R. Sokal, Michael E. Soule, John H. Thomas, 



