On homology

  title={On homology},
  author={Kevin C Nixon and James M. Carpenter},
Homology in cladistics is reviewed. The definition of important terms is explicated in historical context. Homology is not synonymous with synapomorphy: it includes symplesiomorphy, and Hennig clearly included both plesiomorphy and synapomorphy as types of homology. Homoplasy is error, in coding, and is analogous to residual error in simple regression. If parallelism and convergence are to be distinguished, homoplasy would be evidence of the former and analogy evidence of the latter. We discuss… 

Homology and errors

An alternative definition of homology is proposed and primary and secondary homology are defended as realistic representations of discovery procedures in comparative biology, recognizable even in Direct Optimization.

Homology and synapomorphy‐symplesiomorphy—neither synonymous nor equivalent but different perspectives on the same phenomenon

  • S. Richter
  • Biology
    Cladistics : the international journal of the Willi Hennig Society
  • 2017
I, however, do not consider the concept of homology equal or synonymous to that of synapomorphy and symplesiomorphy, as they represent different perspectives on the same phenomenon, i.e. correspondence by common origin.

Homology and misdirection

  • J. Farris
  • Biology
    Cladistics : the international journal of the Willi Hennig Society
  • 2014
Hennig (1966) recognized symplesiomorphies as homologies, and that view is logically correct under the concept of homology (homogeny) prevalent among evolutionists since 1870, and so discarding the purported equivalence of homological and synapomorphy can be avoided.

Deep homology: A view from systematics

  • R. Scotland
  • Biology
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2010
Four examples – three from plants and one from animals – demonstrate that homologous developmental mechanisms can regulate a range of morphological relations including analogy, homoplasy and examples of uncertain homology.

Confusing homologs as homologies: a reply to “On homology”

It seems that systematists, taxonomists, historians and philosophers of biology, perhaps all biologists and palaeontologists, never tire of discussing, expanding and redefining the homology concept.

Homology and Homoplasy: A Philosophical Perspective

A new theory about the mechanical causes of homology is proposed, which states that homologies of character are due to the development of a certain kind of genetic regulatory network called a character identity network.

Serial Homology

Serial homology, i.e., homology between repetitive structures in the same individual organism, is a debated concept in evolutionary developmental biology. The central question is the evolutionary

Why ontogenetic homology criteria can be misleading: lessons from digit identity transformations.

  • R. L. YoungG. Wagner
  • Biology
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2011
Anatomical characters are found to be more reliable than embryological homology criteria when comparing adult structures, because anatomical characters more closely reflect the actions of the developmental genetic mechanisms of character individuation.

Homology in Classical and Molecular Biology 1

There are more kinds of homologous relation between molecular sequences than in morphology, and the terms paraxenology and plerology are proposed for two of these kinds-respectively, the consequence of multiple xenology and of gene conversion.


  • G. Barrientos
  • Biology
    Darwin´s Legacy: The Status of Evolutionary Archaeology in Argentina
  • 2016
The aim of this paper is to underscore the need to enlarge the framework for homology recognition and testing in evolutionary archaeology by adopting a developmental perspective, based on the study of ontogenetic trajectories of artifacts on an individual and population basis.




Logical equivalence between the notions of homology and synapomorphy is reviewed and supported, and a general theoretical solution is proposed to determine evolution of characters with ambiguous distributions, based on the notion of maximization ofHomology propositions.


By dividing de Pinna's term primary homology into topographical identity and character state identity, this work emphasizes the sequential refinement of putative homology statements.

Homology as a parsimony problem: a dynamic homology approach for morphological data

I explore the testing of alternative hypotheses of morphological correspondences in a quantitative cladistic context, and proposes a Bremer support for anatomical interpretations when the specific interpretation is not used.

Coding behavioural data for cladistic analysis: using dynamic homology without parsimony

A new method for the direct optimization of behavioural data, a method that relies on the richness of this database to delimit the characters, and on dynamic procedures to establish character state identity, an important step towards the practical integration of the evolutionary and ecological perspectives on diversity.

An application of dynamic homology to morphological characters: direct optimization of setae sequences and phylogeny of the family Odontellidae (Poduromorpha, Collembola)

The present paper proposes the first application of direct optimization to morphological characters, in the case study of the phylogeny of Odontellidae, and a new homology regime is compared to the traditional homology scheme.

A Numerical Approach to Phylogenetic Systematics

Principles abstracted from Hennig (1966) are used as axioms to form a quantitative analog of phylogenetic systematics and a close connection is demonstrated between phylogenetics and most parsinlonious trees.

Foundations of systematics and biogeography

This chapter discusses the development of Morphology in Germany from Ernst Haeckel to Willi Hennig, and the role of systematics in that development.

Homology and the Optimization of DNA Sequence Data

  • W. Wheeler
  • Biology
    Cladistics : the international journal of the Willi Hennig Society
  • 2001
The criterion of inter‐data set congruence, both character based and topological, are applied to two data sets to elucidate and potentially discriminate among these parsimony‐based ideas.

Toward Defining the Course of Evolution: Minimum Change for a Specific Tree Topology

A method is presented that is asserted to provide all hypothetical ancestral character states that are consistent with describing the descent of the present-day character states in a minimum number of changes of state using a predetermined phylogenetic relationship among the taxa represented.


Abstract— The relations among polarity, outgroups and rooting are clarified. The “outgroup algorithm” and “outgroup substitution method” are irrelevant forms of relaxed parsimony. They should be