ABSTRACT
The clear-cut effects of acute maternal separation and the idea that maternal regulatory interactions might have long-term effects on development led next to a series of studies on the long-term effects of early weaning. The advent of a long period of development in the life cycle, in which the young organism grows and is changed by its interaction with its environment, allows production of wide variations in traits that are thus well adapted to specific characteristics of the changing environment in which evolution is taking place. Although development may allow fine-tuning of adaptations to the environment in one generation, it cannot produce the heritable variation required for it to be considered as major contributor to evolution. C. H. Waddington became intrigued by an environmental effect on the development of the characteristic vein pattern of the fruit fly wing that mimicked rare genetic trait in the population.
