On a similar note, evolutionary changes for the living beings for the last 4 billion years have been identified through the palaentological search. From the fossil records to forensic science (sometimes we use an example of science fiction), the concepts have been implemented to better understand the environment. Ecology refers to the interactions among the living & non-living entities with the environment. It explains that all the levels of living organisms on this planet are dependent on each other through some relationship among themselves. It is very difficult for any organism to fulfill all the basic needs by itself. This leads to our discussion on energy flow from the producers/autotroph/plants to the consumers, and decomposers in the food chain/trophic levels.