What does homology mean?
Homology is the principle that corresponding features or structures can be related through shared origins. In biology, it identifies similarities between organs, tissues, genes, or other features because they descend from a common ancestral structure. This is why the forelimbs of humans, bats, and whales are homologous even though they perform different functions. Homology is also a technical concept in mathematics, where it describes transformations or correspondences that preserve essential structure. In chemistry, it refers to the orderly relationship among compounds in a homologous series. The word is especially useful for distinguishing shared ancestry from superficial resemblance: homologous features may look very different, while analogous features may perform similar jobs without sharing a common origin. Understanding the concept allows readers to interpret evolutionary relationships, compare biological forms, and recognize structural preservation in mathematical and chemical systems.
nounIn biology, homology is the correspondence between structures in different organisms that results from their shared ancestry. In mathematics and related fields, it is a relationship or transformation that preserves the essential structure of a system.
- The correspondence between anatomical or genetic structures in different organisms due to common ancestry.
- In mathematics, a relationship or transformation that preserves the relevant structure of a mathematical system.
- In chemistry, the relationship between members of a homologous series, in which successive compounds differ by a consistent unit such as CH₂.
"The wing of a bat and the wing of a bird are homologous because they have a shared evolutionary origin, even though they function differently."
"Evolutionary biologists identified homology between the forelimbs of humans, bats, and whales."
"The two maps are related by a homology that preserves distances between corresponding points."
The plural is used for multiple biological correspondences, mathematical structure-preserving relationships, or related instances of homology.
"The study compared several homologies between structures in fish and mammals."
Homology means that two features are relatives: they may look or work differently, but they share an ancestral blueprint.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does homology come from?
Homology comes from Greek homos, meaning “same,” and -logy, a combining form associated with the study or science of something. The term developed in biology to describe the correspondence of structures that share a common origin. Its mathematical use preserves the related idea of a correspondence that maintains the structure of a system.
Related word forms
How homology is actually used
In biology, homology describes shared ancestry rather than identical appearance or function; analogous structures perform similar functions without necessarily sharing the same evolutionary origin. The mathematical sense is technical and is used in geometry, algebra, topology, and category theory. In chemistry, the term is usually encountered in the phrase “homologous series.”
Easily confused with homology
Homology concerns correspondence arising from shared ancestry or preservation of mathematical structure, whereas an analogy is a comparison that explains a similarity or relationship between unlike things.