Human acclimatization to cold. A selected, annotated bibliography of the concepts of adaptation and acclimatization...

Every organism has an optimum temperature range within which healthy growth and physiological functioning can occur. At the ends of this range, there will be a minimum and maximum temperature that interrupt biological processes.

Natural selection, a fundamental concept in evolutionary biology, is the mechanism by which evolution is driven, favoring organisms that are best adapted to their environments. This process enhances their chances of survival and reproduction. Adaptation, a key outcome of this process, involves genetic modifications that optimize an organism's functionality under specific environmental challenges, such as extreme cold or thinner air at high altitudes.
Beyond physical adaptations,...

Animal organs and organ systems constantly adjust to internal and external changes through a process called homeostasis ("steady state"). Examples of these changes include regulation of the level of glucose or calcium in the blood or internal responses to external temperatures. Homeostasis requires  maintaining an internal dynamic equilibrium:

The Earth and its atmosphere have provided humans with air, water, and food, but these are not the only requirements for survival. Humans also require a specific range of temperature and pressure that the Earth and its atmosphere provides.
Oxygen
Atmospheric air is only about 20 percent oxygen, but that oxygen is a key component of the chemical reactions that keep the body alive, including the reactions that produce ATP. Brain cells are susceptible to a lack of oxygen because they require a...

Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.

A decreased body temperature can occur in patients with hypothermia and frostbite. Heat loss with extended cold exposure overpowers the body's ability to create heat, resulting in hypothermia. Core temperature readings help classify hypothermia. Mild hypothermia is temperatures between 32 °C (89.6 °F) and 35°C (95 °F) and is caused by impaired thermoregulation. Moderate hypothermia is temperatures between 28 C (82.4 °F) and 32 °C (89.6 °F) caused by...