Everybody knows that humanity's relatively newfound obsession with cleanliness and germ eradication has spawned a host of antibiotic-resistant bacteria. An interesting story in the NYT says that there's a reason kids will eat dirt if you let them - it's an instinctive behavior that provides an evolutionary advantage.
In studies of what is called the hygiene hypothesis, researchers are concluding that organisms like the millions of bacteria, viruses and especially worms that enter the body along with “dirt” spur the development of a healthy immune system. Several continuing studies suggest that worms may help to redirect an immune system that has gone awry and resulted in autoimmune disorders, allergies and asthma. These studies, along with epidemiological observations, seem to explain why immune system disorders like multiple sclerosis, Type 1 diabetes, inflammatory bowel disease, asthma and allergies have risen significantly in the United States and other developed countries.One scientist says: “Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat." He also says kids should have dogs and cats so they can pick up the animals' intestinal worms.