"A must-read . . . Takes you inside a child's gut and shows you how to give kids the best immune start early in life." --William Sears, MD, coauthor of The Baby Book Like the culture-changing Last Child in the Woods, here is the first parenting book to apply the latest cutting-edge scientific research about the human microbiome to the way we raise our children. In the two hundred years since we discovered that microbes cause infectious diseases, we've battled to keep them at bay. But a recent explosion of scientific knowledge has led to undeniable evidence that early exposure to these organisms is beneficial to a child's well-being. Our modern lifestyle, with its emphasis on hyper-cleanliness, is taking a toll on children's lifelong health. In this engaging and important book, microbiologists Brett Finlay and Marie-Claire Arrieta explain how the trillions of microbes that live in and on our bodies influence childhood development; why an imbalance of those microbes can lead to obesity, diabetes, and asthma, among other chronic conditions; and what parents can do--from conception on--to positively affect their own behaviors and those of their children. They describe how natural childbirth, breastfeeding, and solid foods influence children's microbiota. They also offer practical advice on matters such as whether to sterilize food implements for babies, the use of antibiotics, the safety of vaccines, and why having pets is a good idea.  Forward-thinking and revelatory, Let Them Eat Dirt is an essential book in helping us to nurture stronger, more resilient, happy, and healthy kids.