Evolution and Diet: Using Our Ancestral Roots to Lose Weight

New diet plans emerge constantly, often conflicting with one another but always having only a pinch of truth. In a search to have the body of a Greek God while eating ice cream at their heart's desire, Americans constantly seek a magical diet plan where they can fulfill both of these aspirations. However, quick and simple diet plans often fail because the physiological cravings of humans will overcome the willpower of a dieter; but such failings are not without good cause. Ancestral human species evolved unique food cravings in their move away from the tree branches, which still persist today. Though adding frustration in choosing a diet plan today, the unique nutritional regime of early human ancestors played a key role in giving both physical and social form to modern man.

Most modern primate species subsist on fruits and other vegetation found growing on tree branches. While also occasionally known to eat meat, the main emphasis of their diet relies on plant matter. This in itself influenced human evolution, as early cannibalistic practices of prehistoric man resulted in widespread gene loci for resistance to prion diseases, such as Kuru and "mad-cow disease", in response to early consumption of infected individuals (Mead et al). Consumption of infected brain tissue can in turn infect the eater, a problem only for carnivorous species; no such gene is found in other modern primates, as their diets consist primarily of vegetation. But more importantly, the origins of this habit may very well have separated mankind's earliest ancestor from all other primate species of the time. The meat consumption routine of modern humans arose from the actions of an earlier primate ancestor, drawn to the ground and its plentiful food sources for a variety of reasons.

The branches of a tree sustain millions of life forms, but the ancestors of humans took advantage of even better opportunities in a revolutionary move. Modern primates flourish in their niche today, so the food supply in treetops must be able to sustain large, complex mammals. However, a number of factors played a role in pulling mankind's ancestral species to the ground. One probable cause lies in the high protein content available on the ground; large grazing mammals have far more protein available to consume than the insects and nuts residing in branches. Any organism needs a sufficient dose of amino acids to live, and no other naturally occurring food source surpasses protein for this need. Another factor lies in the fact that "bipedal movement is...notably more economical than quadrupedal locomotion at walking rates" (Leonard 199). With the new surplus of energy available from more efficient traveling, human ancestors could then allocate more time and energy to nurturing their offspring.

Ensuring that offspring survives to reproductive age holds great importance for all species on earth. As survival of the individual grows less difficult, more of the individual's time and energy can be devoted to nurture of young. In addition to physically allowing "the arms to carry children and foraged goods", mothers also unconsciously bettered their children (Leonard 109). As a result of the higher metabolic and physical energy allotted to care for young, the conditions for fetal development also improved, leading to a higher quality of offspring. In modern humans, "maternal affects, often assumed to be negligible, account for 20% of covariance between twins" regarding IQ heritability from the mother (Devlin et al 468). The time spent in the womb clearly influences the general mental well-being of a newborn, so a healthier mother would provide a more hospitable and beneficial home to a growing infant. Due to their new diets, mankind's ancestors indirectly bettered their offspring, and eventually the race as a whole, simply by bettering themselves on an individual basis. However, brain size ultimately restricts the mental capacity of newborns, and fulfilling the relatively high metabolic demands of brain tissue can prove difficult.

Fruits naturally contain the sugars that humans crave as a source of glucose, a primary source of fuel to brain metabolism. As brain sizes gradually increased through the progression of ancestral human species, the need for this metabolite increased accordingly. This natural drive to consume sugary foods, while crucial when such sources were rare, has become problematic today. Such foods are readily available now, but our cravings have not changed. As a result, obesity and other disorders run rampant in America as a direct result of this natural proclivity for sweets. Fortunately, the large brains of humans that necessitate this sugar consumption also give the cognitive ability and good sense to not constantly give in to such instincts, difficult as it may be sometimes. Modern humans could technically afford to indulge fairly heavily on the food stocks made readily available, since evolution only demands that a parent lives long enough to raise its young until it reaches a viable age and many of the severely detrimental effects of obesity emerge late in life. However, modern society has many other aspects contributing to quality of life, and mankind now has more on its mind than mere survival and reproduction.

Sharing meals together unquestionably characterizes human interactions. Most holidays and celebrations center upon a feast of sorts, often focusing on protein and carbohydrate-laden dishes, where everyone has a chance to indulge in the intrinsic cravings that characterize all of mankind. While the advancement of civilization has made abundances of food readily available, bodily cravings have not kept up with the times. Surrounded by mountains of sugar and bodies which beg for it, only individuals can decide what course of action to take for themselves; most people know which foods to avoid, but social factors often override this awareness. Needing to fulfill their social needs, humans will use meals as an excuse to mingle and relax with others; a luxury unavailable in the harsh world of mankind's ancestors. Clear evolutionary evidence for such socialization shows up all over the globe.

Every culture may have its own unique regional cuisines, but serve to fulfill the same basic human metabolic needs. The island of Japan houses few large grazing mammals for consumption, but an abundance of seafood in the diets of natives here more than accounts for the protein intake necessary to sustain body metabolism. Subtropical regions contain many indigenous fruits high in sugar content, as well as an abundance of seafood available for other metabolic needs. Numerous other examples exist, each with unique sources of metabolites necessary to sustain human physiology. Socialization intertwines with food in all of these locations, whether through groups of fisherman bringing in the day's catch, farmers working together in fields, or the gathering of a community for a celebratory feast.

Humans adopt diets in hopes of a quick and simple solution in the battle against their internal hunger drives. However, no such resolution exists; minding the ancestral background of modern man helps more than any strict diet plan. In learning of the feeding diversity that helped man take his very form, any strict diet plan immediately loses its appeal. Though sugary, fatty foods sing their siren songs, one must simply acknowledge the evolutionary basis and learn to ignore such callings. Rather than listening to television ads or new trendy diets, a simple understanding of the basic workings of human metabolism will prove far more effective means of living a healthy lifestyle.

Leonard, William R. "Food For Thought" Scientific American. December 2002: 106- 115.

Mead et al. "Balancing Selection at the Prion Protien Gene Consistent with Kurulike Epidemics" Science. April 2003: 640-643.

Devlin et al. "The Heritability of IQ" Nature. July 1997: 468-471.