Evolutionary developmental biology
Evolutionary developmental biology is a field of biological research that compares the developmental processes of different organisms to infer how developmental processes evolved.
Homologous hox genes in such different animals as insects and vertebrates control embryonic development and hence the form of adult bodies. These genes have been highly conserved through hundreds of millions of years of evolution.
Turing's 1952 paper explained mathematically how patterns such as stripes and spots, as in the giant pufferfish, may arise, without molecular evidence.
A gene regulatory network
Heliconius erato
An organism is defined in a medical dictionary as any living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what is an organism. Among the commonest is that an organism has autonomous reproduction, growth, and metabolism. This would exclude viruses, despite that fact that they evolve like organisms. Other problematic cases include colonial organisms; a colony of eusocial insects is organised adaptively, and has germ-soma specialisation, with some insects reproducing, others not, like cells in an animal's body. The body of a siphonophore, a jelly-like marine animal, is composed of organism-like zooids, but the whole structure looks and functions much like an animal such as a jellyfish, the parts collaborating to provide the functions of the colonial organism.
One criterion proposes that an organism cannot be divided without losing functionality. This basil plant cutting is however developing new adventitious roots from a small bit of stem, forming a new plant.
Apolemia, a colonial siphonophore that functions as a single individual
Insect cyborg