As we noted earlier, virtually all motor processes within the human body make use of opposing actuators that drive the particular movable element in opposite directions. The element, whatever it might be, arm, hand, finger, thumb, foot, etc. is essentially in a position of unstable equilibrium such that it requires a positive driving force to maintain a stable position. Otherwise, when any type of force is applied to the element, the element moves at the whim of the external force.

Coupled with antagonistic control mechanisms, the body’s motor control also benefits from the sense of touch in providing tactile feedback to operations with the movable portions of the body. This allows a person to firmly grasp a tool or weapon in order to wield it with force and to also handle delicate objects or structures like infants or eggs.

Most joints in the human body consist of bones held in a fixed but flexible position by strong connective tissue. When coupled with the antagonistic muscle arrangements described above, a great deal of flexibility of position is achieved. Various appendages can bend and, to a certain extent, rotate about various axes. The spine provides the ability for the trunk of the body to bend and to rotate, which allows the upper torso to be positioned at a variety of angles relative to the legs. The same flexibility in the neck allows the head to rotate relative to the rest of the upper body. This particular capability allows the two main long distance sensors of the body, the eyes and ears, to be easily positioned to different attitudes, which in turn enhances the ability of a person to locate and track various threats. Moreover, this ability to reposition the body’s sensors offers the prospect of enhanced cognitive processing of the basic sensor data, and through this processing to develop a better sense of depth perception for visual input and directionality for auditory input. A perhaps more significant facility enabled by the flexibility of the skeletal form is the ability for detailed manipulation of objects.

The arm and wrist can rotate, allowing the hand to manipulate things away from the body as well as things on or of the body. One of the more intriguing anatomical features of the primates is the construction of the hand; specifically, the profound roles of the opposing thumb. No other mechanism in the animal kingdom can offer the same agility in holding and positioning objects. With metaphors building upon the sensori-motor experiences, advanced manipulation capabilities lead to high capacities of abstraction. Geometry, kinematics and topology come to mind; this subject has been extensively studied by George Lakoff and Rafael Núñez in Where Mathematics Come From.

Sustenance for the Mind

Organic life exists within a domain where a collection of physical rules or laws applies. All interactions among members of different species adhere to these physical rules. The human species, like many others, has evolved a variety of mechanisms through which it interacts with the physical world; a collection of mechanisms termed the senses. Within the mechanical world, the senses would generally be characterized as transducers whose purpose is to take purely physical stimuli and convert these impulses into an energy form that can be processed by the central processing unit. Perhaps more appropriately stated for the human body, the stimulus of physical interactions is converted through various senses into impulses that can be transmitted through the nervous system to the brain, where they become the fodder for subconscious and conscious thought processes. Computer systems can have analogues to the senses possessed by humans, and then some.

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