The health needs of animals, including Homo sapiens, are determined by their evolutionary background. This is because, through the processes of evolution, species have become well adapted in their innate biological characteristics to the conditions prevailing in the environment in which they are evolving.
If an organism is exposed to conditions of life that differ significantly from those prevailing in its natural environment, it is likely to be less well adapted to the new and different environment, and it is likely to show signs of maladjustment. It will be less healthy than in its natural environment. This fundamental evolutionary health principle applies to all plants and animals.
The evolutionary health principle clearly applies to a wide range of physical aspects of life conditions in humans. There is no diet better for humankind than that which was typical for hunter-gatherers. It is also clear that the principle is applicable to some aspects of behaviour. Marked deviations from natural sleeping patterns cause maladjustment, and health is likely to be impaired if patterns of physical exercise deviate markedly from those of humans in the natural habitat.
There are good reasons for supposing that the evolutionary health principle also applies to psychosocial and relatively intangible aspects of life experience. For example, the conditions of life of hunter-gatherers are usually characterised by a sense of purpose in daily activities and plenty of convivial social interaction. Most of us would agree that such conditions are likely to promote health and wellbeing in our own society.
Taking our knowledge of the conditions of life of hunter-gatherers as a starting point, we can put together a working list of physical and psychosocial conditions likely to promote health and wellbeing in our species (see Table 2 in A biosensitive society]. They are referred to as universal health needs, because they apply to all members of the human species, wherever or whenever they may be living.
Not every item on the psychosocial list is absolutely essential for health. Lack of satisfaction of one psychosocial health need may be offset to some extent by the satisfaction of others. On the other hand, every item on the list will, if satisfied, make a positive contribution to health and wellbeing.