BIOLOGICAL AND EVOLUTIONARY DIMENSION

The presence of others is not an invention of the human brain.

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Long before the nervous system developed, some organisms already modified their behavior based on the density of their fellow organisms. This mechanism—known in bacteria as quorum sensing—is perhaps the oldest form of presence detection: not a lived experience, but a fundamental biological fact. It's a graduated signal, not an all-or-nothing one: the concentration of signaling molecules indicates the density of other organisms present, and collective behavior gradually adjusts as this estimate becomes more precise. And this information modifies what the organism does.

 

In insects, fish, mammals, and primates, this principle reappears in ever more complex forms. At each stage of evolution, the presence of others represents a biologically relevant factor—for survival, learning, stress regulation, and group cohesion. The human brain did not invent this sensitivity. It inherited it, transformed it, and brought it to an unprecedented degree of complexity. What bacteria achieve through simple chemical concentration, the human brain achieves through a far more sophisticated probabilistic estimation—but the principle remains the same: the presence of others is never a fixed fact, but a quantity that is continuously reassessed.

 

The biological dimension of the Presence Brain explores these evolutionary roots: why presence constitutes fundamental information for living beings, and how this ancient property has gradually been integrated into the most sophisticated brain architectures — until it has become, in humans, a condition for development, emotional regulation and social bonding.

 

Articles in this series

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Presence before the brain ✅

What if the sensitivity to presence was older than the brain itself? From bacteria to humans, this article explores the biological roots of presence — and shows why detecting that someone is there is perhaps one of the most conserved mechanisms in the history of life.

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The brain never functions alone — social energy conservation (in preparation)

The presence of others alters attention, learning, and performance—not simply as a context, but as a cognitive resource in its own right. This article explores Social Baseline Theory and what it reveals about how the brain uses presence to reduce its energetic and emotional costs.

→ Read the article (in preparation)

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Social facilitation: one hundred years of forgotten research (in preparation)

As early as 1898, experiments showed that the mere presence of a peer alters human and animal performance. A little-known story in psychology and neuroscience—and what it reveals about the foundations of the social brain.

→ Read the article (in preparation)

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Artificial Presence — What happens when the other is not human? (in preparation)

Humanoid robots are altering cognitive performance in a way analogous to a human observer. Does conversational AI create a form of presence? The question is no longer theoretical—and it compels us to clarify what "presence" means biologically.

→ Read the article (in preparation)