62 pages • 2 hours read
Daniel LiebermanThe Story of the Human Body
Nonfiction | Book | Adult | Published in 2013A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Part 3, Chapters 12-13Chapter Summaries & Analyses
Part 3: “The Present, the Future”
Part 3, Chapter 12 Summary: “The Hidden Dangers of Novelty and Comfort”
Lieberman suggests humans value short-term costs and benefits more than long-term consequences—a phenomenon called “hyperbolic discounting.” Consequences are often obscured by the cultural normalization of novel or harmful behaviors, and humans often confuse comfort and well-being. To exemplify, Lieberman discusses the consequences of shoes, reading, and sitting.
The oldest sandals that have been discovered were from 10,000 years ago, and developed societies have normalized wearing shoes and have made being barefoot in public taboo. Among running enthusiasts, two extreme views—one promoting barefoot running and one condemning it—have emerged. Lieberman takes a middle-ground approach, agreeing that humans evolved to travel barefoot but arguing that they have been using shoes for thousands of years without major consequences.
Shoes offer protection and support but cause side effects like preventing callus formation, interfering with sensory perception and stability, and weakening the arches of feet and causing flat feet and plantar fasciitis. Doctors often fail to treat the underlying causes of foot pain, instead treating symptoms by recommending patients wear shoes with stiff soles and arch supports, which may create a feedback loop that perpetuates foot pain. Mismatch issues also arise when people choose stylish, uncomfortable shoes like high-heels, which can cause hammertoes, bunions, abnormal posture, and injuries, and nonporous shoe materials that promote fungal and bacterial infections. Lieberman suggests minimal shoes are safe but proposes most modern shoes lead to mismatch diseases and recommends people, especially children, go barefoot more often.
Reading involves focusing on close, small text for long periods of time—something for which human eyes are not adapted. One-third of children in developed nations develop myopia, or nearsightedness, and require eyeglass prescriptions. Myopia is rare in hunter-gatherers and in people who do not often read, which suggests it is a mismatch disease. While myopia has other causal factors, like genetic causes, the predominant causes of nearsightedness in the modern world stem from the environment, such as spending little time outside or focusing on close materials for long periods of time.
The lens of the eye changes its shape in response to what it is looking at, and prolonged focus on nearby images can permanently change the shape of one’s eye lens and elongate the eyeball, and eyeglasses are a buffer. Several researchers have attempted to identify evolutionary implications of myopia, such as myopia resulting from larger brains, but Lieberman rejects these ideas in favor of the mismatch hypothesis. He suggests preventative measures be taken, such as encouraging children to spend time outside or projecting books onto walls.
Sitting on comfortable furniture is a relatively recent practice. Sitting burns fewer calories, contributing to a positive energy balance, and it can cause muscle atrophy or shortening, bone loss, inflammation, and lower back pain. Lower back pain is one of the most common ailments, and it can occur from both disuse and overuse. Modern society prioritizes comfort, which leads to mismatch diseases. Often the symptoms are treated without regard to underlying causes, resulting in dysevolution. Lieberman does not propose a rejection of modern amenities but argues that mismatch diseases can be prevented through alterations, such as by reading differently to avoid myopia.
Part 3, Chapter 13 Summary: “Survival of the Fitter”
In general, cultural evolution has improved human lives by providing plentiful resources with less work, hygienic conditions, scientific progress, and enrichment. Biological evolution is ongoing, but cultural evolution is stronger, resulting in mismatches between the two. Humans evolved to eat diverse natural foods, to endure prolonged physical activity, and to make and use tools and cooperate with each other; thus, humans are not adapted for modern processed foods, inactivity, and comfort, resulting in mismatch diseases that are debilitating, expensive, and sometimes fatal. Lieberman explores four separate approaches to combating mismatch diseases.
First, Lieberman addresses allowing natural selection to provide adaptations to reduce mismatch diseases. This idea is immediately challenged and discarded: Since mismatch diseases have little to no impact on reproductive success, natural selection cannot effectively address them.
In the second approach, Lieberman considers investing more money into biomedical research. Some researchers suggest biomedical science could devise near-miraculous solutions to mismatch problems, but Lieberman argues these ideas are dangerous and akin to science fiction. Biomedical research is slow, mismatch diseases are complex, and people should not expect miraculous solutions. Studies also show that lifestyle choices are more effective at preventing and mitigating mismatch diseases than are biomedical interventions. However, many individuals lack the motivation to make such lifestyle changes. Medical treatments may promote dysevolution, perpetuating rather than solving mismatch diseases, and mismatch diseases are expensive. Lieberman concludes that biomedical research should be funded, but that researchers should consider potential dysevolutionary reactions to medical treatments. However, this may divert funds away from preventative measures.
In his third approach, Lieberman asks if education and empowerment through public health intervention could equip individuals to make healthy lifestyle choices. Effective public health measures are multifaceted: They warn the public about the consequences of certain behaviors, they teach health-related skills, and they incorporate multiple levels of intervention. Other cultural influences, such as advertising, work against public health interventions, and studies show that health education inspires only minor lifestyle changes. This is likely because humans evolved to crave fatty, sugary, salty foods and to conserve energy, making dieting and exercising difficult to maintain. Lieberman concludes: “The bottom line is that knowledge is power, but not enough” (359).
Lieberman’s final suggested approach is to change the environment. Diseases arise from the interactions between genes and the environment, and since genetics cannot be changed, changing the environment is the remaining option. People are familiar with manipulating the environment to protect children, such as by banning the sale of alcohol to minors. Lieberman suggests that governments should impart regulations to help people make healthful choices while still allowing people the right to make unhealthy decisions. He calls this “soft paternalism.” Current examples include the warning labels on cigarettes and alcohol and ingredient lists.
Since soft paternalism is generally accepted, Lieberman questions to what extent the government should interfere. He returns to mitigating children’s environments, suggesting that schools, and potentially colleges, should increase physical education requirements and that addictive substances, junk food, and fast food should be regulated. While this is more easily accepted, the regulation of adult behavior is more controversial. Instead of banning harmful things, Lieberman suggests taxing them. He also suggests putting warning labels and clear ingredient lists and nutrition information on unhealthy foods, and he argues individuals and companies shouldn’t be rewarded for making, selling, or promoting unhealthy things.
Since cultural evolution created the conditions in which mismatch diseases arise, then cultural evolution can be used to reduce or eradicate such diseases. Social institutions, like governments, need to provide the foundations so people can make healthy choices because evolution did not equip people to do so. If humanity fails to make these changes, preventable diseases will remain prevalent.
Lieberman reiterates the importance of considering evolution to understand the present and the future, and he argues that “survival of the fitter” is a more apt saying than the common “survival of the fittest” (365). Culture, he argues, cannot transcend biology. Humans must work with their biology to prevent mismatch diseases and improve their quality of life.
Part 3, Chapters 12-13 Analysis
In the final chapters, Lieberman stresses the need for widespread cultural change to effectively address mismatch diseases in the face of Evolutionary Implications for Health Practices and Policies. Chapter 12 focuses on why cultural change is necessary, and Chapter 13 examines possible routes of social change. Since his goal is to demonstrate the need for social change, Lieberman’s tone becomes critical rather than informative, and he employs persuasive rhetorical techniques to try and convince the intended audience not only that change is necessary, but that the change must include additional government regulation, which is a controversial idea.
As he nears the end of the text, Lieberman shifts from using a predominantly formal academic tone to using a more satirical tone which is often sarcastic or scornful. He identifies illogical cultural norms, including “[h]aving a certain percentage of people die from automotive pollutants and car accidents is a price we are apparently willing to pay for the benefit of having cars” (319). The word “apparently” implies that humans are capable of devising better systems. In another instance, Lieberman writes:
In 2004, the average American child between the ages of two and seven saw more than 4,400 advertisements on TV for children’s foods but only about 164 public service announcements for fitness and nutrition—a twenty-seven-fold difference! (357).
Lieberman’s focus on children serves multiple purposes. First, the regulation of children’s environments is more socially accepted than the regulation of adult environments. Second, many people, especially parents, are protective of children, so by stressing that some cultural practices are harmful to children, Lieberman may convince some readers of the need for change. This initial convincing is important because Lieberman’s proposed method of enacting change—government regulation—is a controversial topic, as many individuals feel that such regulations impinge on personal freedom. Lieberman implicitly counters this argument by demonstrating that many cultural practices, like advertising, clandestinely impinge on personal freedoms by manipulating people and obscuring the truth.
Liberman also uses rhetorical questions and comparisons to argue for the necessity of certain health interventions. He compares the regulation of unhealthy foods, which are often addictive, to other regulated harmful activities. He asks: “[I]s banning or limiting the consumption of French fries and soda in schools different from requiring children to wear seat belts?” and “is limiting the sale of these foods outside of school different from limiting what kinds of movies they can attend?” (363). In asking these rhetorical questions, Liberman draws comparisons between potential regulatory actions over food consumption and regulations that are now widely accepted (e.g., seat belt use, age ratings for movies) to imply that one type of regulation is just as logical and desirable as the other.
Along with addressing the logical benefits of additional regulation, Lieberman also reinforces the consequences of unregulated culture. He directly states that people are not liable for the illnesses they acquire but that culture is, writing that people “acquire chronic illnesses as they age because they grew up in an environment that encourages, entices, and sometimes even forces them to become sick” (364). This statement suggests that it is illogical to live in a manufactured environment that promotes ill-health when humans are capable of modifying culture to promote health. Through this idea, Lieberman concludes his exploration of Evolutionary Implications for Health Policies and Practices. He asserts that the implications of human evolution—such as inherent cravings for high-calorie foods—should be factored into cultural design, and that well-informed regulations can help improve human health and lives.
