Orthometa

Orthometa is a theoretical framework in comparative anatomy that seeks to quantify the degree of morphological similarity that arises independently in phylogenetically distant organisms. The term was coined in 2023 by evolutionary biologist Dr. Elena K. Sorin in a publication in the journal *Evolutionary Biology*. It derives from the Greek root ortho meaning “straight” or “correct” and the Latin meta meaning “change,” reflecting the idea that divergent lineages can converge on structurally “optimal” solutions to similar ecological challenges.

The orthometa index, the central metric of the framework, measures how closely the skeletal or muscular arrangements of two species mirror each other after accounting for developmental constraints and phylogenetic distance. By employing high‑resolution 3D morphometric data and machine‑learning models, the index assigns a numeric value ranging from 0 (no similarity) to 1 (identical anatomy). Orthometa has been applied to studies of limb evolution in vertebrates, wing structure in insects, and beak morphology in birds, offering a standardized means to assess convergent evolution across disparate taxa.

Despite its growing adoption in comparative studies, orthometa remains a conceptual tool awaiting further empirical validation. Critiques point to potential biases from incomplete fossil records and the difficulty of disentangling functional convergence from parallel developmental pathways. Nonetheless, the orthometa framework represents a significant step toward a quantitative, cross‑taxonomic language for describing and comparing evolutionary convergence.