The ability of human and animal populations to adapt to climate and diet is linked to the natural resources that have always characterized the environment in which they evolved. Human beings and animals therefore have their own climatic needs and dietary habits, differentiated by natural ecosystems (broadly divided into desert, arid, sub-arid, sub-humid and humid zones) distinguished by climatic factors determined by latitude and altitude (average temperature and excursions; rainfall and humidity, duration, composition and intensity of solar radiation, and air movements). These ecosystems select animals with those (physio-anatomical) genetic types best suited to the environment in which they live and which have acquired the ability to synchronize with changes in climate, food availability, and pathogens. From the Arctic Circle to the equator, the metabolic type of an Eskimo, a Lapp, or a northern European is not the same as that of a Mediterranean European or an African (Bantu or North African). In the same way, the animal species and breeds adapted to the various climates have differences in thermal tolerances. For species, have a look at the differences between oryx, camel, zebu, European cattle, and reindeer; and, for the cattle species, and among cattle, the Sanga, Brachiceri, Podolica, Mediterranean, Alpine, and northern Europe breeds.
Each native animal population has its own food needs consistent with the natural resources of its environment and, when bred in natural environmental conditions and following natural systems, they fully meet the needs of human populations in their area, including the nutritional qualities of the products. In this, adaptive behavior at the anatomical and physiological levels, which are different depending on the genetic type, help. There are numerous physiological reactions regarding metabolic increase and thermoregulatory mechanisms that, even in humans, are differentiated according to the adaptation to the environment: food consumption and utilization capacity; water availability and consumption; the production, storage or heat dissipation of nutrients; heat absorption by the environment; acceleration of the respiratory rate and pulmonary ventilation; superficial blood circulation and brain cooling, central and peripheral vasoconstriction and vasodilatation, heart rate, blood composition (for greater tolerance to extreme climates, a high level of hemoglobin, red blood cells, and the blood’s specific weight are useful); the characteristics of skin and body surface exposed to the sun (color, extent and thickness), the density and extent of piliferous coverage (hair diameter, length, and color); the number and functional intensity of sweat glands; and the location of fat deposits.
The animal's ability to live and reproduce in places different from those of origin is therefore limited and cases of spontaneous acclimatization without human intervention are rare and mainly related to the so-called cosmopolitan races, i.e., those less sensitive to climate differences. The transfer of animals from temperate zones to hot ones has always caused problems and in the 1960s scientific literature often dwelled upon the problems of livestock taken to hot areas from temperate ones. (Dudan, 1942; Faulkner and Brown, 1953). At that time, I myself recommended the best definition of climate to guide the selection and import of livestock, greater knowledge of the phenomena of heat resistance, but especially, the selection of native livestock and the expansion of their breeding area.
Stockbreeders have the possibility of offering transferred animals a suitable diet and can use the individual variability to select those which have a greater adaptability to the climate environment into which they are to be introduced. Product quality linked to the nutritional conditions proposed by humans, however, remains excluded. In fact, the nutritional quality of production and of the species and native local breeds managed in natural conditions fully meet the human needs of the very area that consumes its products: cattle, buffalo, sheep, goats, horses, donkeys, pigs, rabbits, hares and other game, chickens, turkeys, ducks, geese, pheasants and other birds, shellfish, mollusks, fresh- and salt-water fish, as well as dogs (chow chow), cats, yaks, gayals, bantengs, Arabian camels, Bactrian camels, llamas, alpacas, vicuñas, guanacos, reindeer, capybaras, mice, ostriches, crocodiles, turtles, snakes, etc. In domestic animals, breeding conditions (climate, greater or lesser fodder availability, greater or lesser physical activity) control the evolution of the muscular fiber types (dark or light) and of the sarcoplasmic and myofibril (actin and myosin) proteins. These muscular proteins in particular have different levels of creatine (with a preventive effect against free radicals) and of indispensable amino acids, especially the branched ones (valine, leucine, and isoleucine) used for the synthesis of neurotransmitters and neuromodulators such as placebo-effect endorphins (the happiness drug) and of calmodulin and carnosine (that control the Ca intracellular levels). In the products of these animals, pigments transferred with the traditional grazing from foods of plant origin, to which their genotype has always been accustomed, are found: xanthophylls, lycopene, fucoxanthin, lutein, violaxanthin, zeaxanthin and neoxanthin, but also carotene, carotenoids, and sesquiterpenes as well as a particular abundance of vitamin antioxidants molecules (A, D, E, especially alpha-tocopherol).