Inheritance of Acquired Characteristics

The proposed transmission of traits an organism acquires during its lifetime to its offspring. The idea is associated especially with Jean-Baptiste Lamarck and contrasts with the modern genetic account of heredity.

Use and Disuse: The proposed principle that frequently used organs strengthen while unused organs weaken. Lamarck treated changing organ use as a way organisms acquired heritable modifications.
Jean-Baptiste Lamarck: French naturalist who proposed an early systematic theory of species change in the early nineteenth century. His theory made acquired traits and their inheritance central to evolutionary change.
Natural Selection: A process in which heritable differences affect survival or reproduction, changing populations across generations. It explains adaptation through differential reproduction rather than transmission of acquired bodily changes.
Modern Synthesis: The twentieth-century framework combining Darwinian natural selection with Mendelian genetics. It established gene-based inheritance and selection as the central evolutionary framework.
Lamarckism: An evolutionary theory associated with Lamarck, emphasizing use and disuse and inheritance of acquired traits. It places this inheritance proposal within Lamarck’s broader account of evolutionary change.
Philosophie Zoologique: Jean-Baptiste Lamarck’s 1809 work presenting his theory of species transformation. This book set out the classic formulation of use, disuse, and inherited modification.
Weismann Barrier: The proposed separation between germline cells and somatic cells that limits hereditary influence from the body. It formalized why many acquired bodily traits were thought unable to alter heredity.
Central Dogma of Molecular Biology: The principle that sequence information generally flows from nucleic acids to proteins, not from proteins back to nucleic acids. It helped clarify why bodily changes do not ordinarily rewrite inherited DNA sequences.
Germline: The cell lineage that produces gametes and transmits genetic information to offspring. Modern heredity generally requires changes to affect reproductive cells, not merely the body.
Charles Darwin: English naturalist who developed evolution by natural selection as an explanation for adaptation and common descent. Darwin also entertained inheritance of acquired effects, while making natural selection central.

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