Can you point me to the scripture that equates human souls to animal souls?
Nope...
Like I SAID... "According to Judaism and Old Testament Scholars.."
What I have read was not referenced or sourced "according to scripture".. It was a historical notation...
Just how those scholars came to that conclusion, I do not know..
Here is one link to a history of the philosophy concerning the existence and nature of the soul..
http://www.newadvent.org/cathen/14153a.htm
Graeco-Roman philosophy made no further progress in the doctrine of the soul in the age immediately preceding the Christian era.
None of the existing theories had found general acceptance, and in the literature of the period an eclectic spirit nearly akin to Scepticism predominated.
Of the strife and fusion of systems at this time the works of Cicero are the best example. On the question of the soul he is by turns Platonic and Pythagorean, while he confesses that the Stoic and Epicurean systems have each an attraction for him. Such was the state of the question in the West at the dawn of Christianity.
In Jewish circles a like uncertainty prevailed. The Sadducees were Materialists, denying immortality and all spiritual existence. The Pharisees maintained these doctrines, adding belief in pre-existence and transmigration.
The psychology of the Rabbins is founded on the Sacred Books, particularly the account of the creation of man in Genesis.
Three terms are used for the soul: nephesh, nuah, and neshamah; the first was taken to refer to the animal and vegetative nature, the second to the ethical principle, the third to the purely spiritual intelligence.
At all events, it is evident that the Old Testament throughout either asserts or implies the distinct reality of the soul.
An important contribution to later Jewish thought was the infusion of Platonism into it by Philo of Alexandria. He taught the immediately Divine origin of the soul, its pre-existence and transmigration; he contrasts the pneuma, or spiritual essence, with the soul proper, the source of vital phenomena, whose seat is the blood; finally he revived the old Platonic Dualism, attributing the origin of sin and evil to the union of spirit with matter.