Chimpanzees have more complex body design than fish, followed by spiders and then bacteria. Yet, we cannot say that chimpanzees have a better body design, because evolution does not necessarily mean progress. Evolution simply means the generation of diversity and selection by nature. It is the adaptability of an organism to the environment that supports its survival, not its complexity. Bacteria which are the simplest life forms still survive today. They are found in varied habitats like hot springs, in ice sheets, etc. only because of their adaptability to the ‘changing environment'. Thus, in evolutionary terms, we cannot say that a particular organism has a better body design.