Researchers apply semantic information theory to a realistic model and find the point where information is important for survival

Living systems, unlike non-living or inanimate objects, use information about their environment to survive. But not all information from the environment is meaningful or relevant to survival. The subset of information that is meaningful, and perhaps necessary for life, is called semantic information.

In a new article published in Life PRXphysicists from the University of Rochester and their co-authors have, for the first time, applied this semantic information theory to a well-known model of living systems in biology and ecology: an organism or agent in search of resources.

Using a mathematical model, the researchers simulated how a foraging agent moves through an environment and collects information about resources. The simulations revealed what the researchers called a semantic threshold: the critical point where information matters for the agent’s survival. Above this threshold, removing some information does not affect survival, but below it, every piece of information is crucial.

By quantifying the correlations or connections between an agent and its environment, researchers help reveal the role of information in that agent’s ability to maintain its own existence.

Correlations as Connections

Imagine a bird in its forest. He knows where to find the food he has stored for nourishment. Suppose you move this bird 100 feet to another part of the forest. “By doing this, you have removed some correlations or connections of the bird with its environment, but there are still enough correlations that it does not affect the viability or the ability of the bird to survive,” explains Damian Sowinski, project manager. author of the paper and a postdoctoral associate in the Department of Physics and Astronomy at Rochester.

Now move the bird 1,000 feet or, more radically, 1,000 miles away.

“Ultimately, the bird will know nothing about its surroundings – all connections are cut off. The bird’s viability goes from actually not being respected to suddenly starting to care. collapse,” says Sowinski.

In contrast, moving a nonliving object like a rock 100 feet, 1,000 feet, or even 1,000 miles does not fundamentally change the connections between the environment and the rock. Indeed, the stone does not use any information – relevant or not – about its environment to maintain itself or reproduce.

“One of the most fundamental things in life is consuming resources when navigating space,” says Gourab Ghoshal, co-author and professor of physics at Rochester. “These new results indicate that our way of thinking – the idea that there is survival-relevant and irrelevant information – is promising when applied in a simple model of resource seeking. The big question now is know if our way of thinking will always apply with more and more complex models?”

From particles to people: how is action born?

Action means acting with a specific purpose or reacting to the environment in a non-random manner. It requires making meaningful connections with the environment – ​​interacting, reacting, and then deliberately acting in ways that are self-sustaining and self-producing.

So, when and how does agency – in an individual, in a group or in a system – arise?

“It’s a deep philosophical question,” says co-author Adam Frank, the Helen F. and Fred H. Gowen Professor in the Department of Physics and Astronomy. “The whole point of scientific progress is to take questions that were once the domain of philosophical speculation and find a way to talk about them quantitatively. This paper does that in a mathematically rigorous way.”

Such a broadly applicable mathematical definition of semantic information could offer new insights across disciplines – from biology to cognitive science, from philosophy to physics – on how living and non-living systems are related. That’s one reason why the John Templeton Foundation, a philanthropic organization that funds academic studies on critical topics spanning disciplinary, religious, and geographic boundaries, supported the team’s research.

“Using this language of information theory, we create a bridge between the mechanistic narratives of the physical sciences and the more informational or behavioral narratives used in the life sciences,” says Sowinski.

Like his colleagues, he is determined to continue the team’s investigation into the fundamental mystery of life. As Sowinski says: “Our work is a promising first step toward answering a larger question: What causes a lifeless rock filled with pebbles to end up covered in useful entities that interact in meaningful ways? with each other and with their environment? »