The earthworm is a simple organism with simple model systems - one of the simplest model systems we can find in fact. But the earthworm has an intestine in which intestinal bacteria extract the nutrition from what it eats, exactly as with people. In earthworms we also find the signal molecule serotonin, which today we mainly associate with the state of mind in human beings.
Rediscovering a signal molecule
“To understand why I am researching earthworms, you need to go far back in time, perhaps as much as 5 million years. Then perhaps the forerunner of what would one day become humans had the same mechanisms as the earthworm does today. If we transfer knowledge about this simple organism to humans, we can better understand the development of our own intestinal flora,” says Knut Rudi.
He pauses, takes a deep breath and continues.
“We believe that the signal molecule serotonin functions as a mechanism that causes the earthworm to stop eating. The truth is that, if the earthworm did not have this little molecule telling it to stop eating, it would eat all the time, until it finally ate so many bacteria that it would be eaten up from inside by bacteria in the intestinal system. This molecule is therefore essential for the worm’s very existence,” explains Knut Rudi.
Connection between mental health and molecules
If we transfer this knowledge over to humans, we could assume that serotonin had the same effect on us around 500 million years ago. Today this molecule is associated with mental health. It is therefore interesting to find out more about the causal relationships.
“Could people with a weight problem have less of the serotonin molecule than others?,” asks the researcher. He is not the first researcher in the world to be fascinated by microbial communities. Charles Darwin was very interested in studying model systems in simple mechanisms like earthworms, and he became interested in how species adapted to their surroundings.
Historical development is important, Rudi believes. He thinks we human beings are concerned about what we see and give no attention to what we don’t see, even though it may be important for our health and our existence. That is why Knut Rudi believes that the humble earthworm, which is perhaps one of the oldest organisms on earth, gets far too little attention.
Undemanding animals
Knut Rudi has two jobs. At Nofima Mat, he researches into microbial communities. He looks at how microbial communities occur and how they develop. This is a wide field of research, which includes microbial communities in food and the significance of bacteria in the intestine for our health. Knut Rudi is also employed as a researcher at Hedmark University College, where he primarily researches into model systems, using the earthworm as his “guinea pig”.
“They are good experimental animals that don’t make many demands. They don’t need much food and they don’t take up much space. A box of earth makes a good long term residence, and we give them a kind of flour mixture now and then,” laughs Rudi.
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