Written by Joseph E. Coover RD, LDN, Aramark Healthcare, Northwest Hospital
I have heard many people advise us to “eat like our ancestors.” I’ve also heard vastly different claims about these ancestors. Some people say that they were staunch vegetarians, but others claim they were hunter-gatherers; there’s also a contingency that insists they were strict carnivores. No matter who they may have been, many people also say that, because of the way they lived, our ancestors didn’t have most of today’s chronic illnesses like heart disease or cancer. My goal is to delve into how our ancestors lived, and whether there is anything we can learn from them.
Prior to the advent of antibiotics and revolutionary medical services, the average life expectancy at birth was less than 40 years old (1,2). This was true in prehistoric times, during the Roman Empire, (27BC – 476AD), and again in England from 1395 -1505 (1,2).
To understand why, you have to see figure 1 below.
Figure 1 (3,4)
Throughout history, infectious diseases had been the top killer of men and women. Three of the top five causes of death in the year 1900, which comprised 31% of total deaths, were causes likely due to infectious diseases, none of which are in the top five causes of death today. The cause of the major population surge in the last two centuries has been due to reduced mortality from infectious and parasitic diseases (5).
Historically, prior to the advent of agriculture, humans were hunter-gathers (6). We had a high reliance on animal-based foods, and studies of today’s hunter-gatherers show that they likely had a higher protein intake (up to 35% of energy) and a lower carbohydrate intake (22 – 40% of energy) (7). Prehistoric diets contained little sodium or sugar due to lack of processing and infrequent consumption of sweets (6).
This may make people wonder why they didn’t die from heart disease or stroke with the same frequency we do now.
One thing to remember is that in prehistoric times humans had to work to eat. We ran to catch dinner, and butchered it before cooking. Obtaining food directly depended on energy expenditure (e.g. physical activity). The men would hunt up to four days a week, and women would gather what was edible among the plants. All members of society were always moving. In fact, post pregnancy, many women carried their children 1500km during the first two years of life. Clearly, hunter-gatherers were fit. (8).
Now compare this to the U.S: In 1990, nearly 60 percent of the U.S. adult population reported little or no leisure-time physical activity (9). The prevalence of this sedentary lifestyle increased steadily with age (9). Research has clearly demonstrated the protective effects between physical activity and the risk for several chronic diseases, including coronary heart disease, hypertension, stroke, diabetes, colon cancer, osteoporosis, and anxiety and depression (10).
Now you can put it together. Due to improved medical care, we are living almost double the lifespan of our ancestors. As we age, we become more sedentary, and are likely to become overweight/obese. Living longer has also caused humans to be more susceptible to chronic diseases. Meanwhile, our sodium intake is almost double the amount recommended. All of this has contributed to the large increase in deaths from heart disease, cancer, and stroke.
9. Centers for Disease Control and Prevention Prevalence of sedentary lifestyle–Behavioral Risk Factor Surveillance System, United States, 1991. Available at: http://www.ncbi.nlm.nih.gov/pubmed/8332116 Accessed: 5/27/11