Body by Darwin

Jeremy Taylor

This book presents the growing evidence that we cannot continue to make progress in health care unless we consider the influences of our evolutionary past. Jeremy Taylor addresses seven areas:

  • Our immune system;
  • Issues regarding fertilization, pregnancy, and childbirth;
  • The effects of upright posture;
  • The development of the eye and macular degeneration;
  • The challenges of cancer;
  • Coronary artery disease; and
  • Dementia.

Each chapter stands on its own. I have chosen excerpts from his discussion of our immune system because these disorders affect such a large (and growing) number of our patients. “It is impossible to get to the root of the very peculiar human immune system and design really effective cures for allergies and autoimmune diseases without a fresh understanding of how the immune system evolved and for what reasons.” p. 7

“The world of our ancestors was a much dirtier place than it is now. Evolution took the expedient route, since microorganisms in prehistory could not be eradicated, of allowing humans to live with them rather than continually fight them. The great collateral cost of self-inflicted damage to our tissues caused by permanently raging immune systems was avoided by handing over the regulation of our immune systems to the microbes inside us, so that we ended up tolerating them. Evolution could not foresee a world where public hygiene, antibiotics, and chemicals that kill 99.9 percent of all household germs has so depleted this microbial population inside all of us that our immune systems no longer mature properly or are properly regulated, giving rise to dramatic increases in allergy and autoimmunity.” p. 8

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The author reviews volumes of research and shares a number of anecdotes including one about a boy with autism whose behavior was so uncontrollable that he had to be institutionalized. Soon after institutionalization, he had a complete reversal in behavior which was caused by chigger bites. To perpetuate his recovery, his immune system is now being treated with infusions of pig whipworms, without which his behavior regresses. This case supports the “hygiene hypothesis which links the bacteria, fungi, and helminths (parasitic worms) in our guts, on our skin, and in our airways and vaginas, with a host of autoimmune and allergic diseases. There is mounting evidence that the composition of all these organisms, living on and inside us – collectively known as our microbiota – can offer protection against a formidable list of autoimmune diseases, including the inflammatory bowel diseases Crohn’s disease and ulcerative colitis, type 1 diabetes, rheumatoid arthritis, multiple sclerosis, and, as we have seen, mental health.” p. 17

“Of all the autoimmune diseases, type 1 (or early-onset) diabetes is rapidly becoming the main scourge of life in the modern, hygienic Western world. Karelia is a large northern European landmass that used to belong to Finland but was partly ceded to Russia during World War II. As a result, the country has been partitioned. Although Russian and Finnish Karelians have the same genetic makeup, including the same susceptibilities to diabetes, the differences in their socioeconomic status and health could not be more stark. One of steepest standard-of-living gradients in the world exists at the border between Russian and Finnish Karelia, with the latter having eight times the gross national product of the former. Yet the incidence of type 1 diabetes, and a host of other autoimmune diseases, is far higher on the Finnish side. Finnish Karelians have six times the incidence of diabetes, five times the incidence of celiac disease, six times more thyroid autoimmunity, and much higher allergy levels than Russian Karelians.” p. 21

“The baby is born with a gut that is almost completely sterile and must be populated immediately with bacteria. If it is breast-fed, it starts to receive one of the most extraordinary products in the natural world. Human breast milk contains a complex array of fats and sugars – fast food – but it also contains immunoglobulin A, an antibody that protects the lining of the human gut and prevents pathogens from attacking and perforating it. It has also been estimated that a breast-fed infant receives over 100 million immune cells every day, including macrophages, neutrophils, and lymphocytes, together with a host of cytokines, chemokines, and colony-sustaining factors – molecules that signal between cells of the immune system and promote their growth. Over seven hundred species of bacteria have been found in human breast milk. It also contains oligosaccharides which the baby is totally incapable of digesting. It is present to feed the bacteria from the breast milk which are colonizing in the baby’s gut”. p. 24

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“Within a week or so after birth, the infant gut, originally sterile, has become colonized by up to 90 trillion microbes. The number of microbes in our guts eventually exceeds the total number of cells in our bodies by a factor of ten. Scientists now refer to the existence of a meta-genome to represent the combined genomes of human and microbiota, a superorganism in which we humans are the junior partner and without which we could no longer exist.” p. 27

“Our resident gut microbiota – the mass of over two thousand bacterial species identified as frequent, long-term inhabitants inside us – is extremely complex. Our relationship with them is so close and intertwined that many of the metabolic signatures that can be identified in human blood, sweat, and urine actually come from our commensal bacteria, not us.” P. 34

microbiumes

“The gut has been called the ‘second brain’ and has its own dedicated nervous system embedded throughout the gut wall. It is becoming increasingly clear that our gut molecules can communicate directly with our brains, and they are implicated in brain development, brain chemistry, behavior, and mental illness.” pp. 36 – 37

This is support for the importance of children getting outside to play in areas that have a variety of foliage comes from a different perspective – as long as we check carefully for tics.

Deer_Ticks_3_species

 

The Power of Play

Let Them Eat Dirt

Gut: The Inside Story of Our Body’s Most Underrated Organ

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