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Corrections from Body by Darwin
Body by Darwin: How Evolution Shapes Our Health and Transforms Medicine by Jeremy Taylor (Purchase it here!)
In his book, Jeremy Taylor examines the evolutionary origins of some of our most common medical conditions. By showing us how evolutionary medicine allows us to think about the human body in novel ways, he delves into the roots of these health problems and unearths how we have become susceptible to certain medical conditions over time. Taylor also suggests ways to apply this knowledge to future medical advances. His first chapter, "Absent Friends: How the Hygiene Hypothesis Explains Allergies and Autoimmune Disease," begins with a case study of Lawrence Johnson and his experiences as a boy on the autism spectrum. Using Lawrence’s case, Taylor assesses the hygiene hypothesis, which argues that our obsession with cleanliness may be making us more susceptible to disease. Let’s explore Taylor’s argument and assess the Age of Autism website in light of Taylor’s book!
Corrections from Body by Darwin: About
Lawrence Johnson’s case:
Lawrence was diagnosed with autism spectrum disorder (ASD) in the 1990s, and his illness was said to severely affect the lives of his entire family. However, when Lawrence had a fever, he would begin behaving like an entirely different boy. His family even remarked: “We’re very happy when he gets sick, because life is wonderful!” When his fever subsided, his autistic symptoms would return. On one occasion, when Lawrence was away at a summer camp, he was bit by chiggers, which again resulted in a remission of his autistic symptoms. The chiggers caused Lawrence to have an immune response that would dampen his autistic symptoms, indicating that at least some of his autism was likely a result of an immune response.
Delving into the hygiene hypothesis:
Jeremy Taylor then craftily navigates Lawrence’s story to ascertain how the hygiene hypothesis explains allergies and autoimmune diseases. He states that Lawrence’s case led his father, Stewart Johnson, to the hygiene hypothesis, which suggests that our microbiota, the organisms living on us and inside us, can protect us from a variety of autoimmune diseases. As Taylor examines how our hygiene, sanitation, and water quality have changed over the years, he observes a correlation between cleaning everything and the rise of autoimmune diseases. Our hygiene has improved, but the incidence of autoimmune diseases has increased as well. Taylor speculates that children with ASD may genetically inherit a hyperactive immune system, which increases their susceptibility to developing an autoimmune disease. This is supported by the fact that seventy percent of children with ASD have severe bowel irritation. Taylor then recounts the history of the hygiene hypothesis and how it suggested that an early exposure to organisms would prime the immune system to develop acquired immunity. However, he takes a novel approach in assessing the length of evolutionary time that humans have been exposed to such organisms compared to our modern pathogens such as measles or cholera. He calls these older organisms, primarily helminths, fungi, and bacteria, our “old friends.” Taylor suggests that while modern diseases have not had time to cause much evolutionary change in us, these “old friends” have coevolved to establish, build, and mature our immune systems. Taylor concludes that although the hygiene hypothesis is promising, there is much research left to be done before this hypothesis can become a reliable and effective evolutionary medicine.
Relating the “Absent Friends” chapter to the Age of Autism website:
The Age of Autism website takes cases like Lawrence Johnson’s and jumps to conclusions. In doing so, it is clear that the purpose of the website does not align with the purpose of Taylor’s book. Taylor stresses that “autism is a complex, multifactorial illness and that the therapeutic application of all the science associated with the hygiene hypothesis, for a variety of autoimmune and allergic diseases, is still very much in its infancy and largely unproven.” This word of caution when proceeding with research on the possible ties of ASD to the hygiene hypothesis is what separates Taylor’s scientific work from the “bad science” evident in the Age of Autism website, which never makes a similar statement. Taylor addresses that Lawrence’s treatment is just a single experiment, and thus, he acknowledges the challenges to its generalizability. Age of Autism does not. Instead, it uses its cherry-picked evidence as credible support for its preconceived conclusions. Taylor states that the research in this field is compelling, but he cautiously navigates this information, unlike the website, which uses such information in an attempt to sway individuals. Taylor also cites a variety of other cases related to C-sections, multiple sclerosis (MS), and more. Though the Age of Autism website mentions multiple cases as well, its references differ. The website deliberately selects excerpts of evidence in favor of its conclusions. Meanwhile, Taylor listens to what microbiologists, physicians, and other credible sources have to say, and perhaps most importantly, he recognizes that this applied science is in its infancy and that further research is required. Age of Autism does not.
Corrections from Body by Darwin: Text
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