What is a knife an example of?

A knife is by no means the first, but surely the most successful example of humane ingenuity through all time. Opposed to many animals humans possesses no sharp and strong claws or teeth. Our nails are made for finer work, peeling and such. The invention of the knife is a purposely "backward" evolution to make up for the loss of sharp teeth and strong claws. The one who bears a knife is also the one who bears the strongest symbol of power, showing of the mayor distinction between the human world and the animal world

• a symbol to distinguish man from nature.