Table 1.

Background and significance for the reinterpretation of heterochrony.

The concept of heterochrony was first introduced by Ernst Haeckel in 1875 as the mechanistic basis for his Biogenetic Law.

Heterochrony is due to a change in function or form during development.

Kolman (1885) used the term paedomorphosis to describe heterochrony as process for retaining juvenile properties.

De Beer (1930) used the term neoteny as a subcategory of heterochrony to describe the retention of earlier developmental properties.

Peramorphosis is used to describe delayed maturation and extended periods of growth.

In his book “Ontogeny and Phylogeny”, Stephen J. Gould described the significance and importance of heterochrony as the mechanism of evolution. However, he never provided a specific mechanism for how and why such changes occur, obviating the possibility of scientifically testing its hypothesized role in evolution.

Since the late 1970s, the determination of growth and differentiation by soluble growth factor-mediated cell-cell signaling has been acknowledged to be the mechanism of development.

Despite this, the advent of Evolutionary Developmental Biology, or EvoDevo has not assimilated growth factor signaling into its analyses.

The current article demonstrates the value added in understanding heterochrony as a sequence of cell-cell interactions that can be modified by environmental factors to understand how and why evolution has occurred. The power of this approach is in its ability to understand the processes of development, physiology, homeostasis and pathology as one continuous, scale free evolutionary mechanism for the first time.

This explanation of heterochrony offers a change in the language of evolutionary biology, representing what Kuhn [14] referred to as a paradigm shift in his “The Structure of Scientific Revolutions”.