Theories and Observations of Developmental Biology

Abstract

Developmental biology is one of the most active and fastest expanding areas of biology if not of all natural sciences. The development of many species is intensively studied at many different levels of organization, from the molecular to that of the integral organism. Yet there is no underlying or unifying theory of development, no theory with its own formalism and laws, and there are not even any informal generalizations applicable to unrelated organisms. This lack of a theory is certainly not due to lack of activity or imagination on the part of theoretical biologists, but rather to the basic intractability of the problem. In the present paper I attempt to indicate the major directions of effort and the connections in the presently pursued theoretical work. I cannot, however, begin to descuss the biological consequences and supporting data of these theories, in other words their empirical status, it would require an entire treatise to do so. An overview of some of the abstractions may still give a useful perspective of this field to the workers in developmental theory construction as well as to philosophers of biology who have not covered this area up to now.