Let’s take it a step further and focus on blood pressure in particular. When your blood pressure is taken, it is reported as something like 120/80. The first number refers to systolic blood pressure. This is the peak blood pressure when your heart beats. The second number is diastolic blood pressure, the blood pressure during the resting phase of your heartbeat.
There are standard classification schemes in Western biomedicine that place these numbers into the following categories (Gurven et al., 2012).
Hypertensive (high blood pressure) 140/90 or higher
Prehypertensive 120-139/80-89
Normotensive 120/80 or lower
Using a blood pressure wrist cuff, take your resting blood pressure while seated and breathing normally and note it for yourself. Wait five minutes and take it again. Average the two numbers. Note the numbers in the table below.
Reading One
Reading Two
Average
Now, get up and walk around the room or walk up and down a flight of stairs, then take it again. Note if you observe a difference.
Reading Three - after movement
Now, think about something stressful or exciting that happened recently in your life, and take another reading. If the reading changed, why might this be the case? Which other biological systems mentioned in Chapter 16 are at work altering blood pressure in this case?
Reading Four - after stress
Now, view the short video clip How Bloodpressure Works from TEDEd illustrating how blood pressure works and the causes and consequences of hypertension. Pay attention to dietary impacts on blood pressure that contribute to heart disease.
How does salt in the diet impact blood pressure?
How do fatty foods impact blood pressure?
Define the term atherosclerosis.
Explain what a stent is and how it functions.
Data from hunter-gathers, horticulturalists, and pastoralists show typical blood pressures lower than those usually observed in the U.S. (110/70, for example), and they do not tend to rise with age (also typical in the U.S.) except in cases of changes in diet and lifestyle due to modernization (Gurven et al., 2012). Refer back to Chapter 16 or do some research online and note the kinds of foods these groups typically eat and their levels of physical activity.
Pastoralist Diet and Exercise
Horticulturist Diet and Exercise
Hunter and Gatherer Diet and Exercise
Western Diet and Exercise
Which column most closely matches your own diet? What differences in diet and physical activity between foragers and your society might account for these differences in blood pressure?
If you are working in a group, describe any differences between members of your group based on diet (gluten free, vegetarian, etc.) and daily physical activity (heavy/moderate/light exercisers) and see if those appear to map onto differences in your blood pressure readings.
Given what you saw in the video clip on blood pressure, what kinds of health issues might result from the differences in diet you observed between foragers and yourself or members of your group?
Step Two: The Endocrine System
Review the section of Chapter 16 that addresses nutrition, glucose metabolism and diabetes.
Next, examine the glucose levels provided in the following data set of ten individuals from a modern, industrialized society:
Individuals
1
2
3
4
5
6
7
8
9
10
Glucose Readings
132
126
62
87
160
102
110
98
251
149
Normal glucose levels fall between 70 and 150 mg. Glucose levels are usually lower in the mornings and rise after meals. Blood sugar levels consistently above 150 are indicative of hyperglycemia, or high blood sugar. Chronic low levels, falling below 70, are characteristic of hypoglycemia, or low blood sugar. Both are potentially fatal. Symptoms of hypoglycemia are lethargy, impaired mental functioning, irritability, and loss of consciousness. Persistent hyperglycemia results in diabetes mellitus, the most common disease related to failure of the body’s ability to regulate blood sugar.
Watch the short video Glucose, insulin and diabetes from Kahn Academy which explains the difference between Type I and Type II diabetes, as well as potential treatments. Note the differences.
Characteristics of Type 1 Diabetes
Characteristics of Type 2 Diabetes
Glucose testing results greater than 240mg/dL may mean hyperglycemia. Test results lower than 60 mg/dL may be indicative of hypoglycemia. In either case, patients should seek out a healthcare professional immediately.
Of the ten individuals whose glucose testing results are pictured in the table above, which subjects tested should consult with a healthcare professional for further testing? Why?
Studies by biological anthropologists (Lieberman, 2020) have shown that hunter-gatherers, horticulturalists, and pastoralists tend to be physically fit due to their daily activities. These same people are less likely to eat very little (if any) refined or processed food or beverages. How are the values of the ten individuals in the table above likely to compare with those of contemporary foragers, gardeners, and herders?
If blood sugar homeostasis (meaning the endocrine system is capable of maintaining insulin balance) is important for health, briefly explain how the body’s endocrine system responds to greater and lesser amounts of daily nutrients and physical activity.
Are there limits to how much our bodies can compensate for excess calories or too little physical activity? What is likely to happen if those limits are exceeded?
Step Three: Body Mass Index (BMI)
Body Mass Index (BMI) is a useful measure of overweight and obesity. It is calculated from your height and weight. BMI is an estimate of body fat and a gauge of your risk for diseases that can occur with more body fat. The higher your BMI, the higher your risk for diseases such as heart disease, high blood pressure (hypertension), Type 2 diabetes, gallstones, breathing problems, and certain cancers (NIH, “Assessing Your Weight and Health Risk”).
Although the BMI can be useful, it does have some limits:
It may overestimate body fat in athletes and others who have a muscular build.
It may underestimate body fat in older persons and others who have lost muscle.
It is not normed for different ethnic groups and populations.
Finally, use the measuring tape to measure your waist circumference around your middle just above your hip bones. Use the same website from the previous question to estimate your risk for conditions such as heart disease, hypertension, and Type 2 diabetes.
Waist Measurement
Risk Estimate
Other risk factors include smoking, diet, and lack of physical activity, all of which are regarded as “lifestyle choices” by health professionals. To what degree do you think contemporary health conditions like heart disease, hypertension, Type 2 diabetes, and obesity are structured by your environment?
How does being a college student influence your eating habits? Physical activity patterns? Smoking? Consumption of alcohol? Level of stress? Income level?
How does your lifestyle compare with what you have read in earlier chapters of this textbook regarding the diets, physical activity patterns, and health of our hominin ancestors?
References
Gurven, Michael, Aaron D. Blackwell, Daniel Eid Rodriguez, Jonathan Stieglitz, and Hillard