Interrelatedness among species, an idea developed by Aristotle, was one of the evidences that were used by Darwin to prove his theory of evolution. Aristotle, a Greek philosopher and scientist, was born in 381 B.C. He had many achievements but the greatest of them were the ones that are related to biology. Through observing more than 500 animal species, he was able to show an awareness of interrelatedness among them and also classifying the livings from bottom to top, from his point of view, as follows: Inanimate matter, lower plants and sponges, higher plants, jellyfish, zoophytes and ascidians, molluscs, insects, jointed shellfish, octopuses and squids, fish and reptiles, whales, land mammals and man. Being the first in his time, he grouped