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Last update 1-11-2008

Evolution perspective - the gut

The challenges of the gut

Over time life forms developed larger (eucaryotic) cells and later became multi-celled. This brought a new challenge - the outside became place-to-live for smaller species. That included the inter-species warfare, which now moved on to the outsides of the larger species.

Over time the small species - microorganisms - learned that wriggling between the cells of the large species brought advantages - less fight for space and food for free. Microorganisms learned to invade larger species. If a large species could be killed using chemical warfare or by entering the individual cells a feast of food was to be had. So large species learned to defend themselves from invasion.
HOW??

As species developed from single cell to multiple cells to very many cells feeding the inner cells became more difficult. So cavities developed that acted as food processing units. This stage can still be seen in many aquatic species, such as corals.
In a later stage the cavity developed in to a tube with a mouth end and an anal end.

This development presented these species with new challenges. Until now microbiological attack had come from outside, but these outsides were now inside. Having a full-scale war raging inside you is a challenge. So with the gut the need for elaborate local defenses arose.