The Brain in a Jar

Grumbler

January 26, 2025

Where are your feelings? Where are your emotions? Where are you?

A common trope in fiction, particularly in science fiction, involves the transfer of consciousness to inanimate objects [1] [2] [3] [4] or the brain in a jar [1] [2] [3] [4]. These concepts appear frequently across media, yet they are not often deeply discussed in Sci-Fi bubbles. Perhaps this is because the technologies required to make such ideas possible are so far away, or maybe even just impossible.

The “brain in a jar” trope were we normally have a living, functional brain housed in a container, sustained by some science-y liquid, while continuing to think and exist in isolation. Similarly, the concept of uploading, copying, or transferring a mind into a computer or robot imagines a consciousness existing independent of a human body. Both ideas are, for now, purely speculative and highly improbable, perhaps impossible, which might explain why they don’t always receive the attention they deserve or are not elaborated as much as I would like.

But now, let’s return to my initial questions: Where are your feelings and emotions?

At first glance, it might seem obvious, feelings and emotions are in the brain. After all, the brain interprets and processes them, right? But if we were to separate the brain from the body, disconnect it from all its inputs, what would remain? Not much. The brain is fundamentally an interpreter, dependent on signals from the body to function. These signals come via a huge and intricate network of nerves spanning the entire body, bringing in data from both internal and external environments. The brain processes these signals and sends instructions back to organs, telling them what to do, how to react, like releasing specific hormones. It’s these hormones, circulating through the body, that the brain reads and interprets as feelings or emotions.

In other words, emotions and feelings are a product of hormones produced in the body and interpreted by the brain. This interaction is what creates what we call emotions.

A great example is the gut-brain axis, a real scientific concept that describes how interconnected our emotions are with our physiology. This axis describes the biochemical and neurological signaling between the gastrointestinal system and the central nervous system. Surprisingly, around 95% of the famous serotonin, a neurotransmitter associated with mood and happiness, is produced in the gastrointestinal tract, not the brain. And there’s more! This process is heavily influenced by the trillions of bacteria, fungi, and viruses that reside in our gut!

Let’s absorb this for a moment, your gut, that is also thought as “outside” and not actually inside your body because it is part of a lengthy and continuous tube from your mouth to your rectum, plays a crucial role in shaping who you are. Are the microorganisms inside you the real you, or are you them? The boundaries become confusing when you realize how much of your emotional landscape is influenced by this symbiotic relationship.

So, again, where are your feelings? Where are your emotions? Where are you?

Back to the brain in a jar, without a nervous system or the input of a functioning body, that brain would just be a glorified computer processor, completely disconnected from the sensory and biochemical inputs that make up human experience. Without hormones, without the microbiota, and the intricate web of signals from the body, the brain simply wouldn’t have much to do. It might be capable of thought in some abstract sense, but a “mind,” as we understand it, a mind that feels, anticipates, worries, gets anxious, a mind that dreams, could never exist in this isolated environment.

The mind is not just the brain. The mind is the combination of the brain working in concert with the entire body and the microorganisms living in it.

Now let’s consider the concept of transferring consciousness into a computer or robotic body. The same challenges arise here. Without a physical body capable of providing the several inputs a brain needs, inputs from nerves, organs, and hormones, what’s left is little more than a simulation of consciousness. One might argue that electrical signals could be used to replicate these inputs, but the complexity of the human body, combined with the contributions of our microbiome, makes this an almost impossible challenge.

While we are making advancements in reading parts of the brain, like processing memories, vision, speech, or motor functions, we are still far from being able to map and replicate the intricate interplay of every neuron, every chemical signal, and every gut-microbiome interaction. Even if we could create a digital replica of these processes.

I can imagine a future where humanity will have casual family vacations on the Moon, people working on Pluto doing some mining of necessary minerals (or water), or people working near the sun, collecting its energy and beaming it to colonies around the solar system. But mastering the intricacies of the human mind, in all its embodied complexity? That might take much, much longer, if it’s even possible at all.