There are many different life forms on earth. New species and different sub species are evolving every second as others die out. In order to explain the origin of life, people have used the bible story of creation, while others came up with their own theories. Out of all those theories, the theory of evolution by Charles Darwin seems to have the most supporting evidence to back it up. Evidence on earth suggests that single cell creatures are the ancestors of all life. These organisms slowly evolved into air breathing creatures when oxygen was created. Slowly, the as land dried up, these creatures moved away from the water and on to land where they evolved legs and a strong back bone. The theory of evolution by Charles Darwin explained how life evolved from survival of the fittest, it provides a logical explanation of the evolutionary process these creatures took, and how human came to be. Evidence on earth shows that single cell organisms eventually evolved to multicelled organisms and complex beings. If you look at old fossil records, the oldest fossils are all single cell creatures. These simple creatures do not require oxygen to live. It took in energy from the sun and other energy sources. Slowly as oxygen begins to appear on Earth, some of the organisms began to evolve lungs to breathe oxygen because When free oxygen entered the picture. Breathing is more efficient than drawing energy from the fermentation process that earlier microscope life used. (Science: Biology Pg. 36) Other organisms that did not evolve lungs either died out or went down to deeper depths of the ocean; Oxygen was first consider a pollutant by microscopic creatures. (Evolution Pg. 36) Because of the free Oxygen those who did not change were killed. The evolution through natural selection and survival of the fittest shows that Darwin theory is correct. Due to the lack of oxygen within the ocean , fish slowly evolved to the condition of land. Due to the sudden increase in the population of fish and other marine organism. Due to the sudden increase in the population of marines life, the oxygen level within the ocean decreased. Scientist believe that the lung fish evolved because of a lack of oxygen in the sea. The lung fish learned to rise from the sea and breathe in the oxygen necessary for survival. (Evolution evidence Pg. 38) As more land emerges and dry, rain collected and formed fresh water lakes and rivers. Some of the fish became stranded by the receding ocean. Many fish that became stranded died because they were not able to adapt to the new environment; those fish needed salt water to lived died. But some adapted to their environment. (Evolution Pg. 38) The lobe fin fish was another evolutionary path fish toke to avoid the lack of oxygen in the sea. Fossil record shows that lobe finned lung fish took another evolutionary path. (Microsoft Encarta Pg. 2) The lobe fin fish was almost capable of leaving the water. It only needed more muscles in the joints to be able to lift it self up, because of this many people believe that the lobe fin fish was the ancestor of early reptilian creatures. The different evolutionary paths the fish have taken shows that life changes in responses to different environmental conditions. Fossil records in South America, reveals that there are many sub species of the human race. The fossil of Neanderthal man was discover shortly after Darwin published his book on evolution.. The Neanderthal man was consider to be an ancestor of mankind because of the size of the skull which suggested that it had a small brain. The sloping forehead is also an indication that it is a ancestor of the human race. Not long after the discovery of the Neanderthal was found in the 1890\'s. This fossil was called the Java Man, the Java Man was not consider the missing link between humans and apes. (Evolution Pg. 102) The Java Man was too alike a normal human to be the missing link. The missing link is a fossil of a creature that is in a transitional state between it original form and it new form.(I.e. A dinosaurs with feathers) With the discovery of Lucy in South