16.6: End of Chapter Review

Test Your Knowledge

1. Geographer, historian, and author Jared Diamond (1987) once referred to agriculture as “the worst mistake in the history of the human race.” Given what you have learned about the health consequences of the domestication of plants and animals for humans, how would you respond to his statement?
2. Why do humans like foods that are “bad” for them? Describe the evolutionary underpinnings of our tastes for sugar, salt, and fat.
3. How might understanding contemporary disease from an evolutionary perspective benefit medical practitioners in treating their patients?
4. Given the size of the world population today, humanity could not return to foraging for subsistence. What can we do to promote healthier food consumption on a world scale? How might we build changes into our physical environments to counter the health risks associated with modern diet and activity patterns?
5. Several risk factors for conditions like heart disease, diabetes, and cancer are referred to as “lifestyle factors,” implying these are behavioral choices people make that put them at risk. These include unhealthy eating, lack of physical activity, smoking, and alcohol consumption. To what degree is unhealthy behavior structured by environment? For example, how does being a college student influence your eating habits, physical activity patterns, smoking, and consumption of alcohol?
6. Who benefits from the global obesity epidemic? Think about the following industries and institutions: How might the medical establishment profit from obesity? The fitness industry? The diet industry? Fashion? Pharmaceutical companies? Food manufacturers? Advertisers?
7. Can you think of any human traits in addition to height, wisdom teeth, and immunity from HIV that might be undergoing selection? How would you go about investigating those traits to find out if this is true?

GLOSSARY

Autotrophic: Autotrophic organisms are capable of producing their own food using inorganic substances such as light, water, carbon dioxide or chemical energy.

Body Mass Index (BMI): A person’s weight in kilograms divided by the square of their height in meters. The most widely used measure for identifying obesity. The formula using kilograms and meters (or centimeters) is: weight (kg) / [height (m)]² . The formula using pounds and inches is: 703 x weight (lbs) / [height (in)]² .

Cancer: A collection of related diseases in which some of the body’s cells begin to divide without stopping and spread into surrounding tissues.

Cardiovascular Disease (CVD): A disease of the heart and blood vessels, often related to atherosclerosis, CVD is a condition in which a substance called plaque builds up in the walls of the arteries, blood vessels that carry blood away from the heart, compromising the flow of blood to the heart or brain.

Central Nervous System: The complex of nerve tissues stemming from the brain and spinal cord that controls the activities of the body.

Circulatory system: The biological system that circulates blood around the body via the heart, arteries, and veins, delivering oxygen and nutrients to organs and cells and carrying waste products away.

Diabetes Mellitus: An endocrine disorder in which high glucose (blood sugar) levels occur over a prolonged period of time. Blood glucose is your body’s main source of energy and comes from the food you eat. Insulin, a hormone made by the pancreas, helps glucose from food get into your cells to be used for energy. Sometimes your body does not make enough—or any—insulin (Type 1 diabetes) or does not take up insulin well (Type 2 diabetes). Glucose then stays in your blood and does not reach your cells.

“Double Burden”: Refers to parts of the world in which there is a prevalence of chronic disease (e.g.,. cancer, heart disease) while, at the same time, there are also high rates of infectious disease due to poverty, malnutrition, poor sanitation, and lack of access to health care, often accompanied by high rates of maternal and child mortality.

Ecological model: Ecological models of health and disease emphasize environmental and policy contexts of behavior, while incorporating social and psychological influences, rather than focusing on individual behaviors. These models encompass multiple levels of influence and can lend themselves to more comprehensive health interventions.

Emerging Infectious Diseases (EIDs): Infections that have recently appeared within a population or those whose incidence or geographic range is rapidly increasing or threatens to increase in the near future. Examples include Ebola, Zika, SARS, and avian (bird) flu.

Endocrine system: Those organs in the body whose primary function is the production of hormones.

Epidemiological transition: A transformation in patterns of disease (morbidity) and death (mortality) among a population.

Glucose metabolism: The body’s evolved mechanism by which we turn food into energy for bodily functions.

Glycemic Index (GI): A system that ranks foods on a scale from 1 to 100 based on their effect on blood-sugar levels. Carbohydrates with a low GI value (55 or less) are more slowly digested and metabolised causing a lower, slower rise in blood glucose and insulin levels.

Hypertension: High blood pressure. Blood pressure is the force exerted by the blood against the walls of the blood vessels. In a blood pressure reading, the top number (usually higher) refers to the systolic pressure, the amount of pressure in your arteries during the contraction of your heart muscle when your heart beats. The bottom number is the diastolic pressure when your heart muscle is resting between beats. Hypertension can lead to severe health complications and increases the risk of heart attack and stroke.

Incidence: The rate at which new cases of a disease occur in a population over a given period of time.

Insulin: A hormone produced in the pancreas that regulates the amount of glucose in the blood. Lack of insulin or the inability to absorb insulin causes diabetes.

Metabolic Syndrome: A cluster of conditions, including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol levels that occur together, increasing the risk of heart disease, stroke, and diabetes. Lifestyle changes like losing weight, regularly exercising, and making dietary changes can help prevent or reverse metabolic syndrome.

Menarche: The first occurrence of menstruation.

Morbidity: The number of cases of disease per unit of population occurring over a unit of time.

Mortality: The number of deaths attributable to a particular cause per unit of population over a unit of time.

Noncommunicable Diseases (NCDs): Also known as chronic diseases, NCDs tend to be of long duration and are the result of a combination of genetic, physiological, environmental, and behavior factors. The main types of NCDs are cardiovascular diseases (like heart attacks and stroke), cancers, chronic respiratory diseases (such as chronic obstructive pulmonary disease and asthma), and diabetes.

Obesity: A medical condition in which excess body fat has accumulated to the point that it has adverse effects on health. The most widely used measure for identifying obesity is the Body Mass Index (BMI), a person’s weight in kilograms divided by the square of their height in meters. A measure of 30 kg/m² is considered obese and 25—29 kg/m² overweight. Distribution of body fat also matters. Fat in the abdominal region has a stronger association with Type 2 diabetes and cardiovascular disease, meaning waist to hip ratio and waist circumference are also important indicators of obesity-related health risk.

Obesogenic: Promoting excessive weight gain. For example, an environment in which tasty, cheap food filled with excess calories is abundant.

Osteoarthritis: Refers to the degeneration of joint cartilage and underlying bone, causing pain and stiffness. In the absence of previous injury, it is most common in modern populations from middle age onward.

Prevalence: The proportion of individuals in a population who have a particular disease or condition at a given point in time.

Sedentism: Living in groups settled permanently in one place.

Stress response: A predictable response to any significant threat to homeostasis. The human stress response involves the central nervous system and the endocrine system acting together. Sudden and severe stress incites the “flight or flight” response from the autonomic nervous system in conjunction with hormones secreted by the adrenal and pituitary glands, increasing our heart rate and breathing and releasing glucose from the liver for quick energy.

Stroke: A stroke occurs when a blood vessel leading to the brain is blocked or bursts, preventing that part of the brain from receiving blood and oxygen, leading to the death of cells in that part of the brain.

Syndemic: The aggregation (grouping together) of two or more diseases or health conditions in a population in which there is some level of harmful biological or behavioral interface that exacerbates the negative health effects of any or all of the diseases involved. Syndemics involve the adverse interaction of diseases of all types, including infections, chronic non-communicable diseases, mental health problems, behavioral conditions, toxic exposure, and malnutrition.

Vector-borne diseases: Human illnesses caused by parasites, viruses, and bacteria that are transmitted by mosquitoes, flies, ticks, mites, snails, and lice.

Zoonoses: Diseases that can be transmitted from animals to humans.

FOR FURTHER EXPLORATION

Lents, Nathan H. 2018. Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes. Boston: Houghton Mifflin Harcourt.

Stearns, Stephen C., and Jacob C. Koella, eds. 2008. Evolution in Health and Disease. Second Edition. United Kingdom: Oxford University Press.

Zuk, Marlene. 2013. Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live. New York: W.W. Norton & Company.

REFERENCES

Diamond, Jared. 1987. “The Worst Mistake in the History of the Human Race.” Discover, May: 64–66.