After the institution of better public hygiene, our great guardian, inflammation, no longer busy with outsiders, turned its menacing guns inward. Inflammation is responsible for every important step in the story of atherosclerosis, from its birth as fatty streaks in the lining of the blood vessels, to the dramatic eruption of cholesterol-laden plaques in blood vessels supplying the heart, brain and legs, that activate our clotting cascade, leading to blockages that cause heart attacks, strokes and blood-choked limbs needing amputation.

The third threat to ancient human survival, starvation, existed because of the long intervals that could occur between generous meals. The brain only feeds on sugar, specifically glucose, and therefore it was necessary to maintain glucose in the blood to nourish the brain during thrifty times. And what hormone lowers glucose levels in the blood? Insulin. Therefore, it is hypothesized inconclusively that genes that reduced the effectiveness of insulin were positively selected, raising the glucose levels in the body and now contributing to the pandemic of diabetes. It is also controversially theorized that high cholesterol levels, one of the most important risk factors for atherosclerosis, could have conferred a longer life in prior generations because of a theoretical protective function against infections. These days, however, the lower the cholesterol, the better.

Evolution has a hand in another important driver of heart disease — obesity. Not only did we develop mechanisms to store nutrition to prepare for the inevitable famine around the corner, obesity actually conferred another advantage — it overcharged inflammation. Not only does inflammation cause atherosclerosis, it also accelerates the development of other risk factors for heart disease such as diabetes and high blood pressure.

Evolution may have affected African-Americans even more adversely, as they are very prone to high blood pressure from salt consumption. Natives of Africa had very little salt in their diets and risked losing most of it in their sweat. There is evidence that those that held onto salt in the body were positively selected through evolution. Salt intake in modern societies is several-fold that of what we had consumed for thousands of years. Mechanisms developed to hold onto a previously rare nutrient might be contributing to high blood pressure at a time when salt is ubiquitous. Hypertension, in fact, is much more common in black Americans compared to both white Americans and foreign-born blacks in the United States.

How can we have a chance at reversing these evolutionary mechanisms? Anti-inflammatory drugs repurposed from other conditions such as rheumatoid arthritis have shown mixed results in treating atherosclerosis. Greater benefits could be achieved from anti-inflammatory therapies specifically designed to treat atherosclerosis.