The Hand-Brain Connection
Nearly a quarter of your brain's motor cortex is dedicated to hand movement - an enormous amount of neural real estate for such small body parts. This disproportionate brain allocation reveals just how crucial our hands have been to human evolution and cognition.
If you close your eyes and prepare to hold a variety of objects, your hands do the thinking. A bowl shape for water, a grasp for a warm mug’s handle, a pinch for a few grains of sand, and so on. This extraordinary capacity allows us to shape our surroundings with a purpose and coordination not seen in other species, or robotics for that matter. Manual dexterity has sculpted our neural architecture to manipulate imagined objects, give language to our body, and ultimately power our consciousness.
Cognitive Touch
Hands and speech share deep biological roots. From birth, touching the palms of the hands triggers a baby’s mouth to open. Known as the Babkin reflex, this disappears by 6 months of age, but highlights the profound connection between our developing language and our dexterity. Naturally, this reflex being salient in those early months is an early adaptation to the eye-hand-mouth coordination necessary for food intake, as the control moves from the brainstem and motor cortex to the prefrontal cortex.
In the brain’s map, the hand and mouth regions in the sensory and motor cortices nestle close together, creating fascinating cross-effects. Simply hearing words about "large" or "small" objects actually changes how our hands prepare to grasp things, revealing how deeply language shapes our physical interactions with the world.
The coupling of gesture and language is universal. This is why, in my opinion, natural language processing models for artificial intelligence cannot come close to the multimodal speech-body communication we humans possess.
Rediscovering Manual Intelligence
In our quest for advanced (often humanoid) robotics and technology, we are gaining a better understanding of our own manual intelligence and how it has shaped our lived environment. From perception and active control of our environment, to engagement and mastery of the physics in our world, to the manipulation of imagined objects, the research on dexterity is at the cusp of understanding our own cognition - how we learn is actually through our brain and body in symphony, not in isolation.
Not to get into the nitty-gritty, but there is so much depth to a simple act such as grasping a lemon from a tree. We wouldn’t think more than the conscious “yellow, lemon, want” and we may even verbalize the simplest ‘oh’ but in the coordinated neural networks of the brain-body, we would see immensely complicated feedback systems that work instantly and immediately. The planning of how far to reach, how big to grasp, how forcefully to pull and then experience the sensorial elements, the haptics and all while correcting every minutia of the act to ensure success.
Understanding the profound connection between our hands and cognition, we gain insight into what makes us uniquely human. Our manual intelligence isn't separate from our intellectual capacity - it's a fundamental part of it.
