Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, people were infected with a variety of intestinal worms. The idea, called the 'old friends' hypothesis, is that our immune systems evolved to expect these parasites — and without them, the immune system becomes dysregulated, attacking the body itself or overreacting to harmless substances like pollen or peanuts.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, hookworms and their parasitic kin were ubiquitous companions to our species, and the immune system evolved in their presence. The provocative idea at the heart of helminth therapy is that without these old enemies to fight, our immune systems grow restless and turn on us instead.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, hookworms and other parasitic worms were ubiquitous companions to our species. It was only in the twentieth century that sanitation campaigns, shoes, and antiparasitic drugs largely eliminated them from wealthy countries — and it was shortly after that elimination that rates of allergies, autoimmune diseases, and inflammatory bowel conditions began their dramatic rise.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, hookworms and other parasitic worms were ubiquitous companions of Homo sapiens, and our immune systems co-evolved with them over millions of years. The idea is that without these old friends, our immune systems become unbalanced — overly aggressive, prone to attacking the body itself or harmless substances like pollen.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, hookworms and other parasitic worms were ubiquitous companions — so much so that the human immune system may have evolved to expect their presence. Without them, the theory goes, our immune systems can become overactive, mistakenly attacking the body itself or reacting to harmless substances like pollen or peanuts.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, people were infected with intestinal worms. The worms, in turn, evolved to modulate their hosts' immune responses — keeping inflammation in check so the host could survive and the worms could keep living inside them. The modern, wormy-free immune system, the hypothesis goes, never got that memo and remains primed to overreact.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, intestinal worms were ubiquitous companions. Only in the twentieth century did sanitation campaigns and deworming programs scrub them from the bodies of people in wealthy nations. But some researchers now suspect that in eliminating these parasites, we may have also dismantled part of our immune system's essential operating instructions.

Radiolab

Your Friendly Neighborhood Hookworms

For most of human history, people went about their daily lives with a worm or two (or fifty) in their guts. Only in the past century, with pharmaceuticals and sanitation practices, have we made significant strides towards deworming the whole of humanity. And that's typically been thought of as a good thing, because having too many worms in your body can–quite literally–suck the life out of you. But is it possible to have… too few worms?