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Rapid Change Evolution through the process of Reversion.

 

 

 

In the chromosomes of all animals and plants there must be clusters of genes which are dormant and these are made up of old models and formats from ancestral species. From time to time these dormant gene clusters are accidentally activated during the development. Possible causes for this re-activation could be pathogenic insult (bacterial or viral corruption), toxins from poisonous plants or even natural ionising radiation.

 

In another section we will discuss how embryological development replays the evolutionary process (a phenomenon first observed by Haeckel). During this complex sequence of gene expression - as the organism develops - it is quite feasible that, occasionally, old sections of the sequence could ‘lock in’ during the process. This could result in an alternative tissue type for example.

 

In other instances, the sequence may be arrested at the penultimate point of development. This could explain the ‘throwback’ features in some humans which seem to resemble those of apes. An example of this is the full body pelage (hair covering) which occurs in about one in five billion humans. This premature arrestment of development is an effective way of divesting derived characteristics. A sparse covering of body hair in modern humans is therefore a derived feature.

 

A bird is a very derived creature and all its features are configured for a lightweight build and the mechanics of flight. If a bird were to enter a niche were flight was never necessary, it is conceivable that these features could be an impediment, and that those of a reptilian ancestor would be more appropriate. So junk genes keep options open. Evolutionary adaptation can be thrown into reverse. This is the process of reversion.

 

In this way profound changes in the anatomy or physiology of an animal species can take place between one generation and the next. For example, a new dentition pattern could arise -  such as the change from heterodonty (where teeth are of different shapes and sizes) to homodonty (where the teeth are all the same size), capturing an earlier (ancestral) configuration. Teeth could re-appear in a toothless species. Fibrous scales could appear on an otherwise furry species. Paddles could appear in place of hands or feet.

 

It is not yet known how this process works; perhaps a mosaic of different  island cells exist within a developing tissue and only one type goes on to play the dominant role in the development of the animal, the rest being held as vestigial tissue types.

 

These alternative tissue types may be represented by the moles and patches of different textured skin on our bodies. Dark coloured moles may be vestigial islands of cells which originally produced a black skin, port wine stains may represent skin cells which could produce a red skin if their development was fully expressed.

 

This type of evolutionary adaptation has none of the incremental intermediate stages between one form and another that occur in the other type of adaptation already discussed. Accordingly, this explains the lack of fossil intermediates, a matter which has been puzzling biologists for many years.

  

Evolutionary Stasis

 

 

There is a common misunderstanding that animals are on some kind of evolutionary time clock where there is a gradual change towards greater complexity by some mutational process. I have even been asked the question, “why haven’t all monkeys evolved into apes?”

If there are no constraints on a species population, then no evolution takes place and the animal or plant will stay the same indefinitely. Therefore many species of animals have remained unaltered for tens, or even hundreds of millions of years. Some bacteria in fact have been around in their current form for billions of years.

 

Mutation only plays a small part in the evolutionary process as it most often causes deleterious effects. Gene cluster damage can often be repaired through out-breeding.

 

Oceans have provided the most constant environments as they have always been in existence and extensive in their range. Therefore one would expect that fewer constraints would have acted on the creatures of the sea. The evolution of marine animals has, indeed, not progressed to the degree of complexity and intelligence as shown by some land animals. In fact not much has really happened in the oceans, in terms of evolution, over the last 400 million years. The only really intelligent animals in the oceans are derived from land animals which had become evolutionary advanced on land before entering the oceans. These are the cetaceans, the whales and dolphin family.

 

 

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