Technical Abstract: For centuries, it has been recognized that during limited ontogenic periods, subtle environmental influences can alter the course of human development and thereby affect an individual throughout life. As Dubos pointed out in his 1966 article(1) such "early influences" have most commonly been recognized to affect human behaviour. A huge body of work from the past 40 years, however, illustrates convincingly that in addition to conditioning behaviour, early environmental influences on developmental pathways help shape individual anatomy, physiology, metabolism, and gene expression. Dubos proposed that this area of research might develop into a new science called "biological Freudianism". Considering the various connotations now associated with the term "Freudian", it is probably a good thing that Dubos' proposed terminology never caught on. Rather, the term "programming" proposed by Alan Lucas(2) is now widely associated with persistent structural or functional changes caused by a broad range of early environmental influences. Waterland and Garza more recently proposed the term "metabolic imprinting"(3) to encompass a subset of adaptive responses resulting specifically from early nutritional influences. Recognizing the extensive contributions of David Barker, and his popularization of the concept that a majority of adult disease originates "in utero"(4) it is not uncommon for scientists to refer to the "Barker Hypothesis"(5).