Human Variation

All human beings have much in common, so much that we speak of the ‘brotherhood of man’.

The statement that all men are created equal can only be a statement of belief that all individuals have a right to attain their full development,
and not that they are equal in the sense of
being alike and endowed with equal potentialities.
The spice of our life lies in our diversity, each of us a unique contribution to the life of the earth, for better or for worse so far as the rest are concerned.

The most striking example of how greatly human beings can differ from one another without in any way being less perfectly formed or fully human is seen not in the differences between races or between individuals generally, but between the sexes. Genetically the differences exhibited by the two sexes primarily relate to the presence of one X-chromosome in the cells of males, and two X chromosomes in the cells of females, and so to the chain of developmental processes dependent upon this difference, with particular reference to the development of hormone-producing tissues. Yet virtually every quality of the developing and fully developed organism is affected, shown not only in the sexual structures as such and in secondary sexual characteristics such as mammary glands, hair, voice, and fat-dependent contour, but in blood, relative size of heart and rate of heart beat, emotional and mental qualities, resistance to stress, etc. That male and female are so different is taken for granted without appreciating the fact that within either sex,
although within narrower limits, individuals also vary considerably in almost every distinguishable characteristic.

The ratio of normal to abnormal usually being reckoned as 95:5. This may have some significant meaning, but it completely obscures the fact that every human is a deviate in some respects and that only as this is understood can we fully appreciate the basis of human individuality and the general importance of human variability. A few examples must suffice. The human hand, for example, upon which so much human performance depends, is no assembly line product. The hand of each individual - to be more precise we should specify the right hand or whichever of the two is the master hand - has a distinctive pattern of muscles, tendons, and nerves, altogether as unique as the thumb print itself, which is commonly used as unmistakable identification of the unique individual. The individuality of the hand is seen in handwriting and in the host of other skills which differ so greatly among individuals, such as manual dexterity, finger dexterity, tweezer dexterity, typing ability, the capacity to perform as a violinist, pianist, surgeon, etc., in all of which the skill is both born and made..

Individuals are born with brains that differ enormously in fine structure and are extremely variable in the number, size, and arrangement of nerve cells. No two brains are alike, nor are the sense organs of sight, hearing, smell, taste and touch. By the same token no two individuals live in the same world of senses or understand and make use of the same sensory information the same way. Moreover the greater the brain, the greater may be the differences, so we can see in the creations of the brains of Shakespeare, Beethoven, da Vinci, and Einstein. And individuals physical and mental capacities, in fact his growth and his very life, also depend on how well the organism is serviced by the blood circulatory system. Exceptional performance by body or mind is usually correlated with unusually good arterial supplies to muscles or brain, red blood cell counts at birth for instance vary form 4.46 to 7.29 million per cubic millimetre and in adults from 4.6 to 6.2 million per cubic millimetre,
all normals for the individuals concerned.

In young men the normal heart rate, with the body at rest, has been found to range from 45 to 105 per minute, with pumping capacities ranging from 3.16 to 10.81 litres per minute. Hearts themselves come in all shapes and sizes, within certain limits, though all are normal; while a major artery in one individual may have a cross section and carrying capacity three times that of another. And the capacity of the lungs for air intake, upon which the circulating blood depends for its oxygen uptake and C02 elimination, ranges among so-called normal individuals form 3.5 to 14.4 litres per minute.

The paradox of being human is that we are all of one kind, whatever our race or appearance, and that we are at the same time, each one of us, a unique individual with unique potentialities and, unless overwhelmed by the forces of conformity, with a unique outlook on life and the universe around us.
This diversity is possibly mankind’s most valuable possession,
to be cherished as such.

Recognition of it is the basis for tolerance. It is the birthright of every individual, the right to self-fulfilment, not because men are created equal, but because they are created different. And it is the hope of man’s evolutionary future, for out of this variability we can choose our goals,
if we but have the wit to choose them wisely.

-- Author Unknown