Editing Homology (biology) (section)

===In mammals===
{{further|Comparative anatomy}}

The three small bones in the [[middle ear]] of mammals including humans, the [[malleus]], [[incus]] and [[stapes]], are today used to transmit sound from the [[eardrum]] to the [[inner ear]]. The malleus and incus develop in the embryo from structures that form jaw bones (the quadrate and the articular) in lizards, and in fossils of lizard-like ancestors of mammals. Both lines of evidence show that these bones are homologous, sharing a common ancestor.<ref>{{cite web |title=Homology: From jaws to ears — an unusual example of a homology|url=http://evolution.berkeley.edu/evolibrary/article/homology_06|publisher=UC Berkeley |access-date=15 December 2016}}</ref>

Among the many [[List of related male and female reproductive organs|homologies in mammal reproductive systems]], [[ovaries]] and [[testicle]]s are homologous.<ref name="Hyde2010">{{cite book |last1=Hyde |first1=Janet Shibley |author-link1=Janet Shibley Hyde |title=Understanding Human Sexuality |last2=DeLamater |first2=John D. |author-link2=John DeLamater |date=June 2010 |publisher=[[McGraw-Hill]] |isbn=978-0-07-338282-1 |edition=11th |place=New York |page=103 |chapter=Chapter 5 |chapter-url=http://highered.mcgraw-hill.com/sites/dl/free/0072986360/238525/hyd86360_ch05.pdf}}</ref>

Rudimentary organs such as the human [[coccyx|tailbone]], now much reduced from their functional state, are readily understood as signs of [[evolution]], the explanation being that they were cut down by [[natural selection]] from functioning organs when their functions were no longer needed, but make no sense at all if species are considered to be fixed. The tailbone is homologous to the tails of other primates.<ref>{{cite book |last=Larson |first=Edward J. |author-link=Edward Larson |title=Evolution: The Remarkable History of Scientific Theory |publisher=Modern Library |year=2004 |isbn=978-0-679-64288-6 |url-access=registration |url=https://archive.org/details/evolutionremarka00lars |page=112}}</ref>

{{anchor|In plants}}