In the opening what is the town comparred to? Why do you suppose he makes this comparison

Steinbeck compares the town to a "colonial animal”. The town has become a separate entity from the indigenous people. Steinbeck says it has a "separate nervous system" I have always taken this to mean that the town operates separately from the values, beliefs and practices of the natives. Like the colonials it sucks up whatever worth it can out of its struggling people, just as it will try to do to Kino.