How the Body Shapes Thinking
Thinking isn't just in the brain
We often imagine thinking as something that happens only in the brain. However, thinking involves the whole body.
The brain is made up of billions of neurons. These cells send signals using electrical impulses and chemicals called neurotransmitters. When we think, remember, or plan, patterns of activity spread through the brain’s networks.
Different brain regions handle different tasks. The prefrontal cortex handles reasoning and decision-making. The hippocampus manages memory. The amygdala processes emotions. These regions work together as a system.
The brain also changes with experience. This is called neuroplasticity. Learning a new skill and living in a new environment rewires the brain.
How the Body Affects the Mind
The nervous system connects the brain with all parts of the body, and thoughts are influenced by our physical experiences and states. The nervous system constantly sends signals about physical states, such as hunger, pain, or fatigue, which influence decisions and emotions.
The gut, sometimes called the “second brain,” has over 100 million neurons. It affects mood, memory, and focus through the gut-brain axis.
Emotions are physical as well as mental. Fear speeds up the heart and tightens muscles. Calm slows the breath.
Mental tasks require energy and biological support. When the body is low on resources, thinking becomes harder, not because the brain is broken but because the whole system is under strain.
The Vagus Nerve
The vagus nerve is a major link between the brain and the body, and is often called the “second brain.” It runs from the brainstem to the stomach, connecting to the heart, lungs, gut, and other parts, and sends signals in both directions.
The vagus nerve plays a crucial role in regulating mood, digestion, heart rate, and social engagement. It’s part of the parasympathetic nervous system, the system that helps us calm down after stress. A healthy vagus nerve supports calmness, emotional balance, and a sense of connection.
Thinking and the Body’s Systems
Thinking uses the body’s systems directly. If you imagine kicking a ball, the brain areas that control leg movement activate. If you read the word “lemon,” areas tied to taste and smell activate. This process is called sensorimotor simulation.
We mentally replay experiences using the same systems we use to move and sense. This helps with memory, imagination, and problem-solving.
Even our language shows this. We say people “grasp” ideas or “get a handle on” problems. These phrases reflect how we think through physical experience.
How Our Physical Form Shapes Thought
Our thinking is also fundamentally shaped by the kind of bodies we have. The brain evolved alongside the body, and the structure and abilities of our body directly shape the structure and style of our thoughts.
Our language and metaphors are heavily visual because vision is our dominant sense. We talk about “points of view,” “seeing the light,” and “I see what you mean.” If our main sense were echolocation or smell, as in bats or dogs, our concepts, metaphors, and worldviews would be very different.
The fact that we walk upright on two legs, use hands to manipulate objects, and have opposable thumbs has given rise to tool use, gesture-based language, and spatial reasoning tied to hand-eye coordination. Our mental models are rooted in a world experienced through these bodily capacities.
If we had different bodies, or we flew instead of walked, moved on all fours, or had more or fewer limbs, our minds and thinking would be very different. A being that flies conceives of space, motion, and danger in ways that are alien to ground-dwelling creatures. A creature with tentacles has a radically different conception about causation, control, and self. Octopuses don’t have a centralized brain but evolved to have brains in their tentacles.
Thought is not just something the brain does, but something that emerges from the interaction between brain, body, and environment.
Thanks. Big ideas concisely put.
Most of our brain runs our bodies without our knowing about it. I get so fed up with spiritual types who brush off our bodies as "merely the body," as if we exist independently from it. Balderdash! I treasure my body even though I barely know how marvelous and interconnected it is. Incarnate when we can.
I also noticed your "gesture-based language." When someone is talking on the phone, they're still gesturing with their hands. It's not as though we're saying, "Now I'll move my arm this way or that." Instead, it just moves, part of our communication. Getting a public speaker to do this naturally is about as hard as getting someone who speaks with gestures to not use them.
Finally, the Vagus Nerve and the (badly-named) parasympathetic nervous system. I work out at the Y to help my muscles, posture, and state of mind. Muscles fire to contract, but nothing relaxes them. The chemistry slowly unconnects, or other positions pull them loose. While exercise is great for vitality, so are the ways to practice relaxing. Yoga, meditation, extended exhales, and anti-anxious, anti-regretful states of mind help "strengthen" our parasympathetic ability.