Since the dawn of human thought, humans have endeavored to explain their world. But to really appreciate the reason and nature of our being, we shouldn’t ask why, but how. If we ask why we will be met with a range of superficial answers. The question of how is met only with the answer of Natural Selection (Darwin, 1859); for everything that exists in the biosphere can be explained by this process and the evolutionary history of life. The evolution of Modern Man during the late Paleolithic era has led to an evolutionary paradigm, where we are essentially living outside of our physical environment of evolutionary adaptiveness (Danziger, 2001).
Environmental selective pressures (Cordain, Gotshall and Eaton, 1997), are the thread of Natural Selection, and these selective pressures are responsible for shaping those genetic characteristics which are unique to our species (Cordain et al., 1997). Our genome has remained largely unchanged since the Hunter Gatherer setting of the late Paleolithic era (Chakravarthy and Booth, 2004) and “... the complex interrelationship between energy intake, energy expenditure and specific physical exercise requirements” (Cordain et al., 1997) still exists as it did on our evolutionary stage. Ultimately “we are living in a pathogenic environment” (Green, 2005) and the dissociation between the selective pressures of our past and the unique demands of our present is initiating a cascade of syndromes of impaired genetic homeostasis (Batchelder, 2000). This radiates from perhaps the most vital prospect of modern medicine, and a fundamental component of cardiac health, the presence of a gene which causes “exceptionally efficient intake and utilization of food” (Neel, 1961) and requires “obligatory physical activity for survival” (Chakravarthy and Booth, 2004). A Thrifty Gene.
Humans have an instinctual predisposition to increase their evolutionary fitness, and pass their genes on to subsequent generations. This premise forms the basis for modern medicine and health care. In fact, it forms the premise for much of the way we live our lives. Any factor which increases this fitness, by reducing our mortality and morbidity is therefore a survival advantage. Reducing the instances of cardiac disease is one such factor. The importance of this initiative cannot be understated, with Cardiovascular Disease the leading cause of death in Australia. 13% of Australians suffer some form of Cardiovascular Disease, and Coronary Artery Disease is the leading cause of premature death (Green, 2005). As is apparent, any initiatives to curb the instances of Cardiovascular Disease will have an evolutionary benefit on our fitness. One of the major risk factors for Cardiovascular Disease is Obesity, with a 10% increase in body weight equating to a 20% increase in the risk of coronary disease (Green, 2005). However, it is not obesity that is the pathogen, but the factors it causes, with hypertension (300% increased risk in overweight individuals) (Green, 2005), atherosclerosis and hypercholesterolemia the major components which will be discussed herein. To track down the underlying culprit in Cardiovascular Disease, we must ask what it is that causes obesity. In basic, the answer…Physical Inactivity and incorrect nutrition.