3 minute read
Our arms and hands originated as the forelegs of Vertebrates and, although profoundly refined since those simpler beginnings, the foundational structures, particularly in Mammals, can still be identified. The evolutionary breakout from the constraints of weight-bearing on the forelegs could only have happened once the primary functions of movement and stability had been mastered by our hind legs and feet, resulting in our complex bipedal gait and stance. Bipedal stance and gait are discussed in the section on the LOCOMOTIVE CORE.
The rear legs of mammals function in compression while the front legs function in tension – the fronts legs pull the body forward while the rear legs push. If vertebrate forelegs functioned in compression, with a rigid articulation as found in the pelvis, the evolutionary breakout that resulted in our species Manipulation Core would be improbable. Tensional mechanics are more flexible and, therefore, inherently adaptable (from an evolutionary perspective) than compressional mechanics. The section on Biotensegrity discusses this in more detail.
The primates from which we descend conquered the three-dimensional space of the forest canopy by developing the ability to grasp branches and pull themselves forward with their forelegs. Grasp is an extension of the tensional dynamics implicit in the forelegs. Upon our lineage realizing efficient bipedal stance and gait, the tension-based dynamics inherent in their forelegs enabled rapid evolutionary change in the structural qualities of the arms and hands and their development into tool manipulators. There are ten (or more) distinct axes of rotation between each Manipulation Core’s origin at the Sternum and the tip of the finger, enabling access to, and manipulation of multiple degrees of freedom within spherical volumes centered on their origination.
Our Manipulation Core is the culmination of the evolutionary drive towards specialization. As creatures evolved, they adopted increasingly complex forms to utilize specific resource opportunities. This drive to specialization resulted in extremely refined variations in structure to exploit distinct opportunities. Charles Darwin illuminated these subtle variations in his study of Galapagos Finches.
The Manipulation Core, unique to our species, is the exception that proves that rule. It is a specialization that evolved as a general-purpose adaptation, enabling specializations limited only by our capacity to imagine the tools we can make. Although our species is far from alone in using tools, our investment of half of our vertebrate locomotive core in a general-purpose tool interface has no parallel amongst our animal cousins.
/The expression of the Manipulation Core is described in the paper on the DOING ARCHETYPE
Our hands embody the evolutionary progression from our quadruped antecedents. A discussion of this journey as expressed in the function of our hands here:
The structure of the Manipulation Core is an adaptation of the locomotive core of our vertebrate antecedents. The anatomy of this core is discussed here:
The function of the Manipulation Core is limited only by the extent of our cognitive capacity. These capabilities differ from the cognitive mechanisms of our antecedents, requiring distinct sensory processing and motor control abilities which are discussed here:
HANDS AS FEET
Crossing the mid-line of our body at the Manubrium also facilitates the engagement of the contralateral arm./
HANDS AS ANTI-GRAVITY DEVICES – THE THIRD SPATIAL DIMENSION – SEMI-SPHERICAL VOLUME –
A discussion on our core structural attributes:
THE FOUR CORES
A discussion on the models for our species presented on this website