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Tuesday 1 June 2004



Definition: In a finalist point of view, a biological function is the reason some object or process occurred in a system that evolved through a process of natural selection.

That reason is typically that it achieves some result, such as that chlorophyll helps to capture the energy of sunlight in photosynthesis, and hence the organism is more likely to survive and reproduce.

A function is in relation with a structure ( biostructures ). This is the structure-function relationship.

Organ functions

See : organ functions

The notion of system (or apparatus) relies upon the concept of vital or organic function / organ functions : organ systems are a set of organs with a definite function.

This idea was already present in Antiquity (Galen, Aristotle), but the application of the term "system" is more recent. For example, the nervous system was named by Monro (1783), but Rufus of Ephesus (c. 90-120), clearly viewed for the first time the brain, spinal cord, and craniospinal nerves as an anatomical unit, although he wrote little about its function, nor gave a name to this unit.

The enumeration of the principal functions - and consequently of the systems - remained almost the same since Antiquity, but the classification of them has been very various,[1] e.g., compare Aristotle, Bichat, Cuvier.[3][4]

The notion of physiological division of labor, introduced in the 1820s by the French physiologist Henri Milne-Edwards, allowed to "compare and study living things as if they were machines created by the industry of man."

Inspired in the work of Adam Smith, Milne-Edwards wrote that the "body of all living beings, whether animal or plant, resembles a factory ... where the organs, comparable to workers, work incessantly to produce the phenomena that constitute the life of the individual."

In more differentiated organisms, the functional labor could be apportioned between different instruments or systems (called by him as appareils).

Types :

- biological functions

  • molecular functions : protein functions
  • organelles functions
  • cellular functions
  • tissular functions
  • organ functions
  • system functions
  • systemic functions / organism functions

- physiological functions

  • In physiology, a function is an activity or process carried out by a system in an organism, such as sensation or locomotion in an animal.
  • This concept of function as opposed to form (respectively Aristotle’s ergon and morphê) was central in biological explanations in classical antiquity, and in more modern times formed part of the Cuvier–Geoffroy debate.


- The Concept of Function in Biology. John V. Canfield. Philosophical Topics. Vol. 18, No. 2, Philosophy of Science (Fall 1990), pp. 29-53.

- Concepts of function in biology.W. J. van der Steen. 1999. doi : 10.1046/j.1420-9101.1999.0002j.x

- Teleological Notions in Biology. 1996; 2003.