âº a gradual process of change and development. âº biology Evolution is the process by which the physical characteristics of types of creatures change over time, new types of creatures develop, and others disappear. (Definition of âevolutionâ from the Cambridge Academic Content Dictionary Â© Cambridge University Press)
You can remember the difference between endotherms and ectotherms if you remember that endo- means inside endo- = inside and ecto- means outside ecto- = outside, so endotherms generate their own heat from within, and ectotherms get their heat from the outside.
Polar animals are either covered in winter coats of fur â which traps warm air close to the body â or else large quantities of fat, sometimes inches thick. Fat does not transfer heat very well, so it keeps it inside the body. Humans, with naked skin and relatively little fat, just arenât built for these environments.