The Evolution of the Dragon, by Ellliot Smith

I did some search on Gutenberg.org about the subject fantasy art (for my book "Much Ado About Fantasy Art History) and found this scientific article (book) about dragons. The Evolution of the Dragon, by Elliot Smith (PROFESSOR OF ANATOMY IN THE UNIVERSITY OF MANCHESTER) from 1919.
Very interesting one, maybe not for an average reader but for the more intellectual one....
If you are into ancient time, history, archaeology and anthropology maybe you will find it fascinating. Here a fragment from the article:

In the earliest records from Egypt and Babylonia it is customary to portray a king's beneficence by representing him initiating irrigation works. In course of time he came to be regarded, not merely as the giver of the water which made the desert fertile, but as himself the personification and the giver of the vital powers of water. The fertility of the land and the welfare of the people thus came to be regarded as dependent upon the king's vitality. Hence it was not illogical to kill him when his virility showed signs of failing and so imperilled the country's prosperity. But when the view developed that the dead king acquired a new grant of vitality in the other world he became the god Osiris, who was able to confer even greater boons of life-giving to the land and people than was the case before. He was the Nile, and he fertilized the land. The original dragon was a beneficent creature, the personification of water, and was identified with kings and gods.

But the enemy of Osiris became an evil dragon, and was identified with Set.

The dragon-myth, however, did not really begin to develop until an ageing king refused to be slain, and called upon the Great Mother, as the giver of life, to rejuvenate him. Her only elixir was human blood; and to obtain it she was compelled to make a human sacrifice. Her murderous act led to her being compared with and ultimately identified with a man-slaying lioness or a cobra. The story of the slaying of the dragon is a much distorted rumour of this incident; and in the process of elaboration the incidents were subjected to every kind of interpretation and also confusion with the legendary account of the conflict between Horus and Set.

When a substitute was obtained to replace the blood the slaying of a human victim was no longer logically necessary: but an explanation had to be found for the persistence of this incident in the story. Mankind (no longer a mere individual human sacrifice) had become sinful and rebellious (the act of rebellion being complaints that the king or god was growing old) and had to be destroyed as a punishment for this treason. The Great Mother continued to act as the avenger of the king or god. But the enemies of the god were also punished by Horus in the legend of Horus and Set. The two stories hence became confused the one with the other. The king Horus took the place of the Great Mother as the avenger of the gods. As she was identified with the moon, he became the Sun-god, and assumed many of the Great Mother's attributes, and also became her son. In the further development of the myth, when the Sun-god had completely usurped his mother's place, the infamy of her deeds of destruction seems to have led to her being confused with the rebellious men who were now called the followers of Set, Horus's enemy. Thus an evil dragon emerged from this blend of the attributes of the Great Mother and Set. This is the Babylonian Tiamat. From the amazingly complex jumble of this tissue of confusion all the incidents of the dragon-myth were derived.

When attributes of the Water-god or his enemy became assimilated with those of the Great Mother and the Warrior Sun-god, the animals with which these deities were identified came to be regarded individually and collectively as concrete expressions of the Water-god's powers. Thus the cow and the gazelle, the falcon and the eagle, the lion and the serpent, the fish and the crocodile became symbols of the life-giving and the life-destroying powers of water, and composite monsters or dragons were invented by combining parts of these various creatures to express the different manifestations of the vital powers of water. The process of elaboration of the attributes of these monsters led to the development of an amazingly complex myth: but the story became still further involved when the dragon's life-controlling powers became confused with man's vital spirit and identified with the good or evil genius which was regarded as the guest, welcome or unwelcome, of every individual's body, and the arbiter of his destiny. In my remarks on the ka and the fravashi I have merely hinted at the vast complexity of these elements of confusion.