Lamarck's law of use and disuse states that
- A. an organ that is constantly used becomes better developed while a disused organ degenerates
- B. all organs of the body remain unchanged throughout life
- C. organs change only when their genes mutate
- D. an organ once lost can never reappear in any descendant
Explanation
This is the first of Lamarck's two laws, and he used it to explain the strong limbs of a blacksmith, the webbed feet of water birds and the loss of eyes in cave dwellers. His second law, the inheritance of acquired characters, is what turns these lifetime changes into evolution. Modern biology accepts that use develops an organ but denies that the development reaches the offspring.