From embryology, we know that our bodies are organized around three basic cell types: Endoderm, Mesoderm, and Ectoderm. As we grow these cell types attempt to maintain genetically defined ratios to each other. However, these ratios are an approximation and in almost everyone, there is a relative dominance or deficit of one or two of these three cell types. This “imbalance” can be observed in the appearance of the physiology of an individual*.

The emergence of these cell types follows our evolutionary trajectory. The specialized adaptations animals acquired required specialized cell functions. For example, movement requires muscle and skeletal cells (Mesoderm). Movement relies on sense organs and some form of cognition to decide where and when to move (Ectoderm), and all living things need to process, assimilate nutrients to grow and reproduce (Endoderm). These tissue types emerge in utero in their evolutionary sequence. Endoderm is the original tissue type from which Mesoderm and Ectoderm emerge.

It is possible to recognize the relative dominance of these three tissue types in any individual. This activity was called Somatotyping by William H. Sheldon1. Somatotyping can be linked to the Dimensional Mastery Model, offering visual cues as to which evolutionary paradigm is most dominant and hinting at which therapeutic strategies cataloged in the model would have greater efficacy. It is likely that somatotyping is done either consciously or unconsciously by all effective therapists.

The ratio of relative dominance derives from the context within which we develop, the context of our current setting, and the context within which our ancestors thrived – in some situations some core functions afford relatively more benefit than others. These ratios are simple to observe in peoples’ physiology

1 “Atlas of Men, A Guide, and Handbook on Somatotyping” William H. Sheldon 1954


EndomorphRound Body Type
The foundational cell type in our bodies is Endoderm which forms our viscera and organs. This can be thought of as the cell type which shares a common ancestor with all organisms. It is this tissue type that handles the basic processes of life.

Endomorphs are generally more social, more able to simply be present at the moment. Their emotional reactivity trends to grief. They have a stronger sense of the present moment.

In this model Endoderm is the tissue type common to All Living Things and Animals (there is also a correlation to Mammals). The Metabolic Core, and the Persistence and Social Archetypes are the most dominant.

For an Endomorph, it is more likely that the Vertebrate layer will be challenged.


Mesomorph-“V” Shaped Body Type
Movement required the emergence of a cell type to handle this specialized task. Mesoderm is the tissue type of our muscles and skeleton, which we share in some variation with all organisms which move.

Mesomorphs are more action-oriented, often taking the role of a leader in getting things done. Their experience of time is more linear, comfortable stepping through a plan to achieve a goal. Their emotional reactivity trends towards anger.

In this model Mesoderm is the tissue type associated with Vertebrates. The Locomotive and Manipulation Cores and the Doing Archetype will be most dominant.

For Mesomorphs, it is more likely that the Mammal layer will be challenged.


Ectomorph-Narrow Body Type
While animals were figuring out the how of movement, they also needed to figure out the where and why. This required the development of complex sensory systems, and the ability to think through the relevance of what they were sensing.

Ectoderm is the tissue type of our nervous system. It is common for Ectomorphs to state that they feel as if their nervous system is right on their skin, their emotional reactivity trends towards anxiety, and can easily become hyper-vigilant to the potential for threat.

In this model, Ectoderm is associated with Mammals and Primates. The Neurological Core and Intelligence Archetype will be most dominant.

For Ectomorphs, it is more likely that the Living Thing, Animal or Vertebrate layers will be challenged.

 Mixed Somatotypes
The pictures shown above illustrate quite pure forms of tissue type dominance, which are quite rare. We almost always fall into a blend somewhere in the middle of these three types, making assessment somewhat more challenging. These charts illustrate for men and women where we tend to cluster. (Click on the chart for a full-screen pdf)