The Worm Within You

We have legs for locomotion, arms and hands for manipulation, senses for experiencing the environment, and sexual organs for reproducing. Our digestive system seems to exist to provide the energy that serves these other systems, pleasing our brains and giving rise to a happy life. But is that really how it works?

In our evolutionary past, it is believed that our earliest ancestors were simple unicellular organisms known as prokaryotes, appearing around 3.8 billion years ago. These evolved into more complex eukaryotes, and then into multicellular organisms, eventually becoming something called deuterostomes around 550 million years ago. Some of these deuterostomes were wormlike in structure, with bilateral symmetry, a mouth opening for ingesting food and an anus for excreting waste. The food came in, the waste went out.

The need to find food and mates, and to evade predation, led to methods of locomotion that began with undulation, adding fins and other features for efficiency. Olfactory, tactile, and optical senses developed for the same reasons. Yet all the while, the purpose remained the same: find food, reproduce, don’t get eaten. Individuals that succeeded at this passed on their DNA; those that didn’t, vanished.

The strategy of movement enabled these critters to find the resources they sought, rather than needing resources to come to them. It wasn’t the only working strategy; other organisms successfully adopted sessile strategies, in which they stayed in place and filtered nutrients, or lured in prey and trapped it. Mussels and anemones are examples of the latter approaches. All three approaches can involve great complexity, but the organisms on the move had additional requirements. They developed more sophisticated senses, nervous systems, and often brains. They moved from place to place, sensed the environment, and found resources. They were explorers. 

Attachment theory begins with the idea that two basic goals guide children’s behavior: Safety and Exploration. — Jonathan Haidt, Social Psychologist and Author 

These are the origins from which we come, where exploration is fundamental to survival, both for finding food and finding mates. As a consequence, our biological reward systems strongly promote exploration as a primary activity. Meanwhile, we may want to reconsider who is in charge of the show. We may think that moving and manipulating the world, eating, and having sensations, exist for us to experience and enjoy our lives. In this view, we subordinate the worm—the part of us comprising our digestive tract from mouth to anus—to serving us as the source of energy that enables everything else. But from an evolutionary perspective, the worm came first, adding our arms, legs, brains, and other complexity, to serve its pleasure. If we also recognize that the microbiome in our guts contains more non-human cells than we have human cells in our bodies, it may be that we are here to serve the worm, not the other way around. It may be that our drive to explore exists because the worm is hungry, and it is our job to feed it.

Author's note: I am not an evolutionary biologist. This is presented as a speculative view of our origins, what drives us, and as a different perspective on who we are and what controls us.