For hundreds of millions of years, vertebrates refined their mastery of linear movement. Dominant species maintained dominion over the “sweet spots” on the planet, requiring other species to work out niches to survive. The accessible niche in the spatial dimensions is the horizontal plane and these species developed sensing, movement, and awareness that made use of opportunities ignored by those Vertebrates that held sway. These vertebrates, our direct ancestors, are Mammals. About 65 million years ago, a major disruption in the hierarchy of dominance gave Mammals an opportunity to “break out” and with their sensory, processing and movement advantages quickly gained dominance in the Living System.

Action in the horizontal plane requires a more diverse skillset:

  • The antecedents of Mammals were, and still are visually dominant. If you essentially only move towards or away from what is sensed, the line of sight is adequate. Mammals developed their auditory processing, affording them a 360° perspective on their surroundings. Think of how a horse’s ears continually move independently in a 180° arch. Sound sensing is discussed in greater detail in the is paper:
  • Being able to make sense of the complex auditory field required the development of more complex cognitive processing which requires maintaining a map of the surroundings which can then be updated by the incoming data. This map enabled Mammals to maintain awareness of the position, and eventually other aspects of the state of other members of their own group, the origination of complex social dynamics1. This awareness is a more complex cognitive form, which we experience as emotion. Evolution of cognition is discussed in this paper:
    Advanced cognition requires a greater expenditure of energy, as do the decisions afforded by more “intelligent” solutions to rumination. This issue was resolved in Mammals by their adaptation to a higher metabolic rate which maintained a constant internal temperature, a phenomenon which we call “Warm-Blooded”. This is discussed in the paper on the:
  • Awareness of what is occurring to the sides is not very useful if you cannot respond. The antecedents of Mammals were/are muscularly dominant in forward direction movement, with minimal resources invested in movement to the sides. Mammals developed, in addition to powerful advancement, flexibility and mobility to the sides. This is demonstrated by the difference in Spinal Flexion between Mammalian Antecedents (spine flexes to the sides) and Mammals (spine flexes top/bottom, or front/back in our species). This subject is explored in more detail in the paper on
    Mammalian antecedent movement, as observed in those animals that co-exist with Mammals, can be described as either Homologous (like a Snail) or some variant of Heterolateral (cross-lateral). Mammals are competent in both of these forms of locomotion but are also able to move in more complex ways were each (bilateral) side moves independently of the other. These movements or called Homolateral, and are discussed in the paper on:


This additional complexity required a long maturation cycle. Mammalian antecedents could essentially package the complete developmental cycle into an egg, with offspring emerging fully formed and functional. Mammalian development requires additional time/energetic resources, facilitated by complex group dynamics. Our species is an extreme example of this, requiring up to twenty-five years to fully mature and a complex social structure within which this to occur. The emergence of social dynamics as an evolutionary strategy is discussed in this section:

1Advances in research on the correlations between mammals’ cognitive ability to track objects over the horizontal plane through time and their awareness of social structures are elucidated in this Scientific American article, February 2020 “The Minds Social Maps”.

In primitive Vertebrates the principles of Biotensegrity are challenging to apply. However, once Vertebrates crawled onto land, and more significantly when they began loading their body weight through their legs the principle of Biotensegrity gains relevance. Understanding the bipedal gait of the Primates in our lineage Homo is greatly enhanced by a foundational understanding of the principles of Tensegrity as applied to Biological systems, Biotensegrity.

Mammals mastered the shock absorption and energy storage qualities of tensegrity as impressively demonstrated by the Kangaroo, who can move very efficiently, yet quickly, delivering most of the energy captured when it lands into its next push off of the ground.

Tensegrity is the study of how compressional and tension always forces interact in a structure. It greatly enhances the traditional explanations of posture and gait from Neurophysiology, which at best seem incomplete and of limited clinical therapeutic utility. There is a fuller explanation of Tensegrity here:
It is encouraged that the Tensegrity principle is taken on as an area of study for therapists dealing with clients’ physical issues, as well as other issues, as advancing one’s understanding of this principle, enables more holistic therapeutic interventions.

Because this movement dynamic is associated with movement over the horizontal plane, this developmental level is associated with the LEFT/RIGHT(Sagittal Plane). This is the line that assesses the left and right sides of the body relative to the center of gravity of the body. The most common example of this dynamic is our “handedness” or usually right dominant hand.