In the book 'Primal Health' (1986) we proposed a simplified vocabulary in order to adapt to a new scientific context.
The primal period includes fetal life, perinatal period and early infancy (from conception until the first birthday).
Primal health research includes all studies exploring correlations between the primal period and health and personality traits later on in life.
The Primal adaptive system refers to the basic adaptive systems involved in what we commonly call health. The nervous system, the endocrine system, and the immune system should no longer be separated and should be understood as a whole (e.g. the brain is a gland, insulin is a neuromediator, lymphocytes can release endorphins, etc..). We need a simple term such as 'primal adaptive system' to replace complex phrases still used in the scientific literature, (e.g. 'psychoneuroimmunoendocrinologic system').
The 'primal period' may be presented as the period of maturation of the primal adaptive system. Health is how well the primal adaptive system works (it is not the absence of disease). At the end of the primal period we are in a basic state of health called 'primal health'.