"Man in Terms of Millions of Years"

   In spite of somewhat similar titles, these books have little in common, and I am not sure that they agree with each other in their real implications. But they are both brief, well written, and deal with important matters.


   De Cayeux's book, after a confused opening chapter, steadily improves and has new ideas on what might be called "the philosophy of evolution." It describes the development of living forms over billions of years, with special attention to the process and rate of changes in these forms. These changes, we are told, have been continuous, with imperceptible transitions and no clear-cut lines of demarcation between species. The designation of a species as a distinctive type is a subjective mental classification whose limits tend to be narrower on this side of the Atlantic than in Europe. The average period of existence of such a European species is from four to eight million years. The total number of species, however defined, is slowly increasing at a steady rate like compound interest. This rate of increase seems invariable, so that the number of species doubles about every 80 million years. Thus, for every 30 new species which appear, 29 become extinct. Each new form appears in one geographic area, spreads widely and proliferates into different varieties, growing steadily in size and in specialized features, and then begins to decrease in both varieties and in areas occupied until the form is to be found only in remote and peripheral areas as it approaches extinction.


   The rules which De Cayeux finds in regard to species also apply to genera, orders, classes, and phyla, but over much longer periods of time. Genera, for example, have a life expectancy two to three times as long as species, averaging about 10 to 18 million years, while the comparable figure for orders is 230 million and for classes of living forms is 490 million years. All these figures, if projected backward, would place the origins of life on this planet somewhat less than five or even four billion years ago.


   According to De Cayeux, the varieties of living forms become more numerous, more complex, and more specialized over time. Most of these conclusions would be acceptable to De Cayeux's fellow scientists, but toward the end of this book he becomes less orthodox, ending on a note of Christian mysticism similar to Lecomte du Nouy.


   One of his unorthodox conclusions (which seems to a novice like me to be convincing) is his rejection of mutations as a chief factor in the appearance of new species, despite its general acceptance today. He argues that, if mutations played a significant role, the speed of evolutionary change would be notably faster among those forms which have millions of offspring at a time and over short periods, in comparison with forms which have a single young one at long intervals, but, on the contrary, the rate of evolutionary change seems to be about the same for all forms. To explain the appearance of new forms, De Cayeux looks with favor on some still undiscovered mechanism of Lamarckian inheritance.


   Ashley Montagu's volume is typical of this prolific writer who issues a new book about every five months, either as author or editor. As usual, this one is clearly expressed, marvelously well informed and well written, and filled with the humane altruism we have come to associate with this writer's interpretations of scientific evidence.


   The book is not concerned, as the title might seem to indicate only with human evolution but is an introduction to the whole of anthropology, including evolution, races, culture, family and social patterns, social controls and government, and non-material culture such as philosophy, the arts, and the role of anthropology in changing the lives of less developed peoples. An amazing total of information is presented in very brief compass, through clear, concise definitions and explanations, and also in numerous diagrams, maps, and very valuable tables of factual information.


   The point of view is typically Montagu, with its emphasis on the evolutionary process leading to man as a general development from inherited traits toward learned ones and from specialized behavior to more open, free behavior. He shows convincingly that man, from the beginning, had to be a cooperative and nonviolent creature dependent for his continued existence on his fellow humans and shows that recent popular books which have argued to the contrary are grossly mistaken. The whole volume is a model introduction to the subject, and shows more convincingly than the last pages of De Cayeux how revolutionary an innovation the appearance of man has been in the whole evolutionary process. For those who wish to continue their study of this subject, Montagu has provided a thoughtful annotated list "For Further Reading."


-- Carroll Quigley