7.5 Competition and cooperation.
Diversity is an asset to mankind. It should be positively accepted as a fact, not negated as an embarrassing impurity. The facile trend of our time: a uniform treatment of the most diverse human beings, is in need of revision. Diversity maybe promoted and used for the good of society and for the unfolding of its individual members. Not only sports trainers (Tanner 1964) but also educators (Walker 1963) and health workers should be familiar with the fact that there are differences in physique that correlate with different individual inclinations. The great diversity within our species is one of the wonders of mankind. Application of this knowledge does justice to every person's possibilities.
After earlier authors had proposed a similar view, it was Sheldon who collected convincing evidence
that differential strength in development of the germ-layers is at the root of variations in human physical appearance and
that the types of physique correlate with specific domains of excellence and abilities, also in a social and relational context
Although not all his claims have as yet been justified the main body of his theory on human physical and mental development has been well substantiated. Based on the descriptions given by Sheldon in "The varieties of human physique" (1942) we mention some of the criteria for identification of physical properties.
7.5.1 Characteristics of Endomorphy
The body is rounded and exhibits a central concentration of mass. The trunk predominates over the limbs, the abdomen over the thorax, and the proximal segments of the limbs predominate over the distal segments. The bones are gracile and the muscle system is poorly developed. Muscle relief and bone projections are absent. The body displays a smoothness of contour owing to subcutaneous padding.
The head is large and spherical, the face is wide with full cheeks. The neck is frequently short and forms in side view an obtuse angle with the chin. The shoulders are high and rounded. The trunk is relatively long and straight, the chest is wide at the base. The limbs are comparatively short and tapering with small hands and feet.
7.5.2 Mesomorphy.
When mesomorphy predominates, the body is sturdy, hard and firm. The bones are large and heavy, the muscles well-developed, massive and prominent. The heavily muscled thorax predominates over the abdomen. The proximal and distal segments of the limbs are evenly proportioned. The bones of the head are heavy. The face is large in relation to the cranial part of the head. Massive cheekbones and square jaws are the rule. The arms and legs are uniformly massive and muscular, strongly built knees, massive wrists.
7.5.3 Ectomorphy.
"Ectomorphy means linearity, fragility, flatness of the chest, and delicacy throughout the body. We find a relatively scant development of both the visceral and the somatic structures. The ectomorph has long, slender, poorly muscled extremities with delicate pipe-stem bones, and he has, relative to his mass, the greatest surface area and therefore the greatest sensory exposure to the outside world. He is thus in one sense overly exposed and naked to the world" (Sheldon 1942). The facial part of the head is small as compared with the cranial part - just the reverse of mesomorphy. Dolichocephaly (oblong cranium) is common in ectomorphs. The chin is sometimes hypoplastic and receding. The neck is long and slender and projects forward, forming an angle with the body axis. The rounded shoulders hang limply forward, owing to lack of muscular support. Arms and legs are comparatively long, particularly the distal segments.
7.6 Varieties of temperament: genetic disposition of personality