First 'Rule' Of Evolution Suggests That Life Is Destined To Become More Complex

Researchers have found evidence which suggests that evolution drives animals to become increasingly more complex. ... "If you start with the simplest possible animal body, then there's only one direction to evolve in — you have to become more complex.... Sooner or later, however, you reach a level of complexity where it's possible to go backwards and become simpler again. "What's astonishing is that hardly any crustaceans have taken this backwards route. Instead, almost all branches have evolved in the same direction, becoming more complex in parallel. "This is the nearest thing to a pervasive evolutionary rule that's been found. "Of course, there are exceptions within the crustacean family tree, but most of these are parasites, or animals living in remote habitats such as isolated marine caves. "For those free-living animals in the 'rat-race' of evolution, it seems that competition may be the driving force behind the trend. "What's new about our results is that they show us how this increase in complexity has occurred. Strikingly, it looks far more like a disciplined march than a milling crowd."