Epigenetic Mechanisms of the Cambrian Explosion

Chapter I. The Precambrian Evolution

Presents a general picture of the emergence of the animal life, transitions to primitive metazoans found in the fossil record from approximately 700 to 1,000 million years ago until the appearance of the eumetazoans about half a billion years ago. Delves into causes of the almost half billion years evolutionary stasis that characterized this stage of metazoan life. The reasons why Precambrian evolution of metazoans hit a dead end and its fauna became extinct are thoroughly examined.

- Pre-Cambrian fauna of ‘unprogrammed’ forms

-Physical factors in the driving seat

- 3 billion years of evolutionary stasis

- Sponges and placozoans as dead ends of evolution

Although multicellular animals evolved between 700 and 1,000 million years ago, only the latter stage of the Precambrian forms of 580-545 million years ago is studied in some detail. This stage of the Cambrian explosion is now adequately described; the emergence and evolution of Ediacaran forms are discussed. Causes of their extinction and evolutionary stasis as well as possible relations of Ediacaran fauna with the Cambrian forms are discussed.

- Ediacaran pioneers of the Cambrian explosion

- The second informational revolution and the Cnidarian breakthrough

- Differentiation of neuron and neural net: the new type of the control system

- The neuron and the neural net: a result or enabler of the complexity?

- Memorization limitations of the neural net and the extinction of the Ediacaran fauna

With the genetic toolkit demonstrated to have preceded the emergence of phanerozoic fauna, the essential change relevant to the Cambrian Explosion seems to have been the emergence and rapid evolution of the neuron, neural net and the centralization of the nervous system, the evolution of new epigenetic mechanisms and the epigenetic system of inheritance, which seems to have been responsible for memorizing and transmitting the blueprint of the supracellular parental structures to the progeny.

- Generation of the epigenetic information for supracellular structure

- Evolution of the mechanism of binary control of gene expression

- Evolution of the neural control of epigenetic structures

- Epigenetic control of the patterns of placement of parental factors in gametes

- The phylotypic stage: Why should it evolve at all?

- The epigenetic control of the post-phylotypic development

Provides a succinct description of the hypotheses on causes of the Cambrian Explosion and discusses their scientific validity. Based on the author’s epigenetic theory of evolution, a detailed explanation is presented on the mechanisms and driving forces of the sudden emergence and unprecedented rapid evolution of animal forms during the Cambrian, which is incompatible with the Darwinian model of gradual evolution.

- Cambrian explosion is a fact not a peleontological artifact

- Overcoming computation limitations of the neural net - Centralization and growth of the nervous system

- From gradual to the saltational evolution of animals.

- On the highway of evolution: bilaterians shift the gears

- Major morphological results:

- bilateral symmetry and body plans

- advent of triploblasty

- establishment of anterior-posterior axis

- establishment of ventral-dorsal axis,

- advent of specialized organs and organ systems.