PRESENCE BEFORE THE BRAIN
- drissboussaoud
- 3 days ago
- 5 min read
The biological roots of sociality…
Has the presence of others influenced living things for longer than the brain itself? From bacteria capable of detecting the density of their neighbors to human brain networks sensitive to social presence, a central hypothesis of the Presence Brain project is emerging: sociality does not begin with interaction, but with the ability to detect that others are there.
Most theories of the social brain begin with interaction. Some begin with the brain itself. They seek to understand how organisms perceive their conspecifics, communicate with them, cooperate, or build relationships.
The Brain of Presence project leads to a more radical question: what if sensitivity to the presence of others was older than the brain itself?
This question may seem surprising. We spontaneously tend to consider presence as a psychological phenomenon, or even as a conscious experience. Yet, if we go back far enough in the history of life, another possibility emerges. Before being a lived experience, before being a cerebral mechanism, presence could be a fundamental biological fact.
Is anyone there?
To explore this idea, let's imagine a marine bacterium.
It possesses neither a brain, nor a nervous system, nor consciousness in the way we usually understand it. Yet, it is capable of modifying its behavior depending on the number of other bacteria present in its environment. When the density of neighboring organisms reaches a certain threshold, it changes the expression of its genes, adapts its survival strategies, and behaves differently depending on whether it is alone or surrounded.
This mechanism is known as quorum sensing .
Each bacterium constantly releases small chemical molecules into its environment. As the number of bacteria increases, the concentration of these molecules also increases—a continuous, chemical estimate of the density of its kind, rather than a simple count. When a critical threshold is reached, the entire population changes its behavior in a coordinated manner—but this collective coordination relies on information that has never ceased to change gradually.
The bacterium does not directly perceive its neighbors. It perceives their trace. But this trace is enough to inform an estimation, more or less strong depending on the perceived concentration: is someone there? And this estimation modifies what the bacterium does.
This is not a metaphor
It would be tempting to consider quorum sensing as a simple analogy for presence. However, that would be to miss the point entirely.
Quorum sensing is not a metaphor for presence. It is a presence detection mechanism. It allows an organism to adjust its behavior based on the presence of other organisms.
This mechanism has been preserved by evolution because it confers a decisive advantage. In certain situations, survival depends precisely on the ability to take into account the presence of others.
In very different forms, this principle reappears throughout the history of life. A single idea seems to run through evolution: the presence of others constitutes biologically relevant information. And this information modifies behavior.
The brain did not invent presence
This perspective leads us to look at the brain from a slightly different angle.
We often tend to think of the brain as the origin of sociality. However, it might be more accurate to say that it inherited much older mechanisms.
The brain did not invent sensitivity to presence. It transformed it. It amplified it.
He integrated it into increasingly complex forms of information processing.
In social insects, the presence of conspecifics organizes sophisticated collective behaviors. In fish, it regulates school cohesion and responses to predators. In rodents, it influences learning, risk-taking, and stress regulation. In primates, it shapes social behaviors, observation of others, and the acquisition of new skills.
In humans, it penetrates to the finest levels of brain organization, from synaptic mechanisms to the large networks involved in attention, emotions, and social cognition.
Between the bacterium that chemically detects the density of its neighbors and the human being who instantly perceives that they are not alone in a room, billions of years of evolution have passed. But a continuity remains. At each stage, organisms have had to answer the same question: Is anyone there?
An evolving continuity
We often tend to view sociality as a complex property that appeared relatively late in the history of life, thanks to intelligence, language, or consciousness. This intuition is understandable. The most elaborate forms of communication and cooperation do indeed seem to depend on sophisticated cognitive abilities.
But this perspective could lead us to overlook something more fundamental.
What if what we now call social cognition, attachment, cooperation, or communication was based on a much older principle?
What if all these abilities stemmed from a more basic property: the capacity to detect the presence of other organisms and adjust one's behavior accordingly? From this perspective, sociality would not begin with interaction. It would begin with presence.
What this changes
This hypothesis profoundly transforms the initial question.
If sensitivity to presence is a biological mechanism conserved for billions of years — before the nervous system, before the brain, before consciousness — then it is not a late consequence of social cognition. It may well be its very foundation.
Communication, cooperation, empathy, or theory of mind then appear as progressive elaborations of a more fundamental property: the ability to detect that other organisms are present and to adjust one's behavior accordingly.
Understanding presence, therefore, is not simply understanding a dimension of the human brain. It may be understanding one of the oldest and most preserved properties of life.
Before speech. Before thought. Before even the brain. There was already presence. Perhaps understanding presence means understanding one of the oldest roots of sociality.
Articles and links to explore
General presentation of the project and the question that constitutes its starting point.
How social neuroscience has transformed our understanding of the brain, and why the question of presence could complement this theoretical framework.
Why certain ordinary experiences — shared silence, feeling watched, soothing or threatening presence — can help us understand the role of presence in human experience.
In an elevator, a waiting room or a train, the mere presence of another person is often enough to transform our experience.
Videos, reflections and explorations around the neuroscience of presence, attachment, development and psychotherapy.
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