page_title: Heterochrony
section_title: Across the animal kingdom
hierarchical_section_title: Heterochrony / Effects / Across the animal kingdom
caption_attribution_description: English: This file is a redrawn and colored version of a sketchy, colorless diagram from the Journal of Heredity (1921) Volume 12, pg 421. It depicts human body proportions changing as the subject matures. The diagram shows that the head becomes proportionately smaller and the limbs become proportionately longer as the subject matures. The link below goes to the original diagram. File:Neoteny_body_proportion_heterochrony_human.png
context_page_description: In evolutionary developmental biology, heterochrony is any genetically controlled difference in the timing or duration of a developmental process in an organism compared to its ancestors or other organisms. This leads to changes in the size, shape, characteristics and even presence of certain organs and features. It is contrasted with heterotopy, a change in spatial positioning of some process in the embryo, which can also create morphological innovation. Heterochrony can be divided into intraspecific heterochrony, variation within a species, and interspecific heterochrony, phylogenetic variation, i.e. variation of a descendant species with respect to an ancestral species.
  These changes all affect the start, end, rate or time span of a particular developmental process. The concept of heterochrony was introduced by Ernst Haeckel in 1875 and given its modern sense by Gavin de Beer in 1930.
context_section_description: Heterochrony is responsible for a wide variety of effects such as the lengthening of the fingers by adding extra phalanges in dolphins to form their flippers, sexual dimorphism, the neotenous origin of the vertebrates from a tunicate larva, and the polymorphism seen between insect castes.
caption: Neoteny in human development
exif: {}