omologi

Omologi, or homology, is a concept in biology describing similarity due to shared ancestry. When features of two or more organisms resemble each other because they were inherited from a common ancestor, they are considered homologous. This contrasts with analogy, where similarities arise from convergent evolution rather than descent. The term was introduced in the 19th century by biologist Richard Owen and has since become central to anatomy, embryology, and comparative genomics.

Structural or morphological homology refers to bones, organs, or structures with a common evolutionary origin, even if their current function differs. The classic example is the pentadactyl limb of many tetrapods, including human arms, whale flippers, bat wings, and mole forelimbs, which share a common bone arrangement. Developmental homology refers to patterns in embryonic development, such as similar pharyngula stages in vertebrates. Genetic or molecular homology refers to shared DNA sequences or protein-coding genes across species, indicating shared ancestry; HOX genes demonstrate deep conservation of developmental control.

In modern biology, homologous relationships are identified through phylogenetic analysis, comparative genomics, and studies of gene order (synteny). Orthologous genes (in different species, diverged after speciation) usually retain similar functions, while paralogous genes (duplicated within a genome) may diverge. Recognizing homology supports reconstruction of evolutionary trees and helps infer the function of genes and structures in extinct or poorly studied organisms.