Epigenetics Comes of Age

There is an unmistakable correlation between the evolution of the nervous system (differentiation of the nerve cell implied) and the evolution of eumetazoan life during the Cambrian explosion. But does it mean that the correlation is a manifestation of a causal relationship between them?

Even if one could prove the existence of a causal relationship between the evolution of the nervous system and the Cambrian explosion how can we determine whether the evolution of the nervous system is cause of the enormous diversification of animal forms or that the evolution of the nervous system may be e manifestation of the general trend of increased complexity of animal forms in the course of the last half billion years of evolution?

It is true that it is extremely difficult to determine which is the cause and which the effect when dealing with two simultaneously occurring events as the evolution of the nervous system and the Cambrian explosion, when one cannot apply the basic criterion that “cause precedes the effect”. However the situation is not hopeless.

To ascertain the role of the nervous system in this case let’s ask the question: could evolution of eumetazoan life occur and proceed without the nervous system emerging first? The question is hardly hypothetical because multicellular animals that didn’t succeed in evolving a nervous system exist. Sponges and placozoans are two “nerveless” groups of animals. These groups represent “dead ends” of the evolution of metazoan life that remained almost unchanged for about 600 million years while its sister group of cnidarian-like organisms, which evolved  the nervous system, gave rise to the Cambrian explosion and the amazing diversification of animal forms displayed by extant  animal world and by fossil  record.

Developmental biology also offers some relevant clues. The operational central nervous system is the first and the organ system to develop during the early development, at the phylotypic stage and overwhelming signals for the development of other organs and organ systems originate in the nervous system.

Do not these fundamental facts suggest a central role of the nervous system in the Cambrian explosion and post-Cambrian evolution of the animal kingdom? I strongly believe it does.

This entry was posted on Tuesday, June 29th, 2010 at 4:10 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.