An ordering pattern for animals or conditions that is based on age. Often the “value” of different age-grades is thought to increase with age, also referred to as age-positive or positive age-graded pattern. Or the value first increases and then decreases with age, referred to as inverted U-shaped or J-shaped pattern. The latter can turn into an age-inversed pattern, also called negative age-graded.
In its most general form, the term “age-graded” refers to an age pattern underlying a particular condition or a change (i) in an organizational social characteristic; (ii) of an anatomical, physiological, or cognitive feature; or (iii) of a behavior or a behavioral syndrome. Specifically, in the social sciences, the term “age grade” is used to describe an organizational pattern in a society. In developmental biology and individual life histories, age-gradedness is common, because an organism undergoes predictable, age-related changes, for example...