since humanity start to develop culture, the death always had been a important part of it. the traditions related about how to deal with corpses is a must in any culture and is considered taboo to leave it.
In Antigone what I consider a very important part and the beginning of the tragedy is when Polyneikes one of Antigone’s bother wasn’t buried properly. Antigone emphasizes the disgrace, dishonor, pain, etc, of leaving the corpse to fed the birds and dogs. this fact is mentioned across the story and is mentioned multiple times even with the threat of dead. Antigone justify her actions by mentioning the honor one must show to others, the traditions gods impose, the pain she felt, etc. At that time the idea of a life after death was deeply imprinted on people minds and a corpse no treated correctly will represent the eternal suffering for the soul of that body. Many people at that time reinforce that idea to the point that today we can see in the documents left behind, many examples such as the need to put perfume, new clothes, one coin in each eye or under the tongue, and many more rituals considered essential for an appropriate afterlife.
Even in our actual society the fact of leaving a body with no burial is considered immoral and inhuman. The main reason usually discussed is that a corpse may bring illness, but usually the feeling doing something that we must do it, is also an important cause. in our actual culture most religions emphasize the importance of a ritual and even for many of us just the image of a exposed corpse is considered really bad.
As explained before the way to deal with dead body is mentioned many times in the book like in the sentence 30, 290,487, and many more direct as well as indirect references. although I considered that the act of leaving the corpse may have other reasons, is undeniable that this was the spark that initiate the drama.