Complexity is the rule of evolution

Washington, Mar 18 (UNI) Evolution, the gradual change of life forms, follows a long-term trend of driving the creation to become more complex.

A new study published in the Proceedings of the National Academy of Sciences suggested that animals tend to become increasingly complex during the process of evolution.

A team of scientists studied the fossils of crabs, lobsters and their relatives of the crustacean family tree through the last 550 million years, seeking cases that evolved to become simpler than their ancestors.

However, the researchers found organisms with increasingly more complex structures and features, suggesting that there is some mechanism driving the change in this direction.

''If you start with the simplest possible animal body, then there's only one direction to evolve in - you have to become more complex,'' said Dr Matthew Wills, one of the scientists.

Almost all branches of crustaceans have evolved in the same direction, becoming more complex, Dr Wills said, adding this may well be the nearest thing to a pervasive evolutionary rule.

Evolution occurs when some genes in a population spread more widely than others through the group. That normally occurs because certain genes are more advantageous than others. As a result their bearers are able to reproduce more. Ceaseless repetitions of this process leads the whole species to change and become new species, forming a sort of family tree of species.

A seemingly obvious feature of this tree is that complexity constantly increases. The human evolution from apes is the most famous example, the scientists noted.

''The driving trend toward complexity affected all 'free-living animals in the 'rat-race' of evolution,'' Dr Wills added.

It seems that competition may be the driving force behind the trend. It looks far more like a disciplined march than a milling crowd, he observed.

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