Lycanthropy in the Bible?
In the book of the prophet Daniel, chapter 5 we can read a possible instance of actual lycanthropy: 18O thou king, the most high God gave Nebuchadnezzar thy father a kingdom, and majesty, and glory, and honour:19And for the majesty that he gave him, all people, nations, and languages, trembled and feared before him: whom he would he slew; and whom he would he kept alive; and whom he would he set up; and whom he would he put down.20But when his heart was lifted up, and his mind hardened in pride, he was deposed from his kingly throne, and they took his glory from him:21And he was driven from the sons of men; and his heart was made like the beasts, and his dwelling was with the wild asses: they fed him with grass like oxen, and his body was wet with the dew of heaven; till he knew that the most high God ruled in the kingdom of men, and that he appointeth over it whomsoever he will.
From an Evolutionary perspective, it is of course nonsense to suggest that a human could turn into a wolf or vice versa; such a creature would have to have descended from both humans and wolves.
Instead, it's clearly a case of parallel evolution (akin to dolphins and some sharks having similar shapes); a were-wolf doesn't actually turn into a wolf; it merely turns into a wolf-like form. This can be compared with the transformation of a tadpole into a frog or a caterpillar into a moth. The only distinguishing characteristics of lycanthropy are
- the reversibility of the transformation
- the speed of the transformation
- the supposed link in some cases to full moons.
We can deal with these individually.
A non-reversible lycanthropic transformation would be strongly selected against for at least one obvious reason: the difficulty of child-rearing. Unlike true wolves, whose pups are born able to walk and quickly reach a level of maturity necessary to feed themselves, human/lycanthropic children/pups share the standard human multi-year maturation process. A lycanthropic human stuck in wolf-like form is severely restricted in child-rearing ability; for instance, such simple acts as nursing, burping and changing a diaper are beyond the capability of the paw-formed hand. More importantly, the wold-form father cannot teach his daughters about the benefits of abstinence, and generally is not granted admittance to purity proms. Thus, only reversible lycanthropy is selected for.
Second, speed of transformation: since the selection benefits of human lycanthropy revolve primarily around replacing the standard human weakness in the face of attack with the benefits of protective fur, built-in weapons, speed and aggression, the change must happen fast enough to be a benefit in the face of immediate danger. Thus, slow transformation is selected against.The full moon link is the easiest of all to deal with, since it's entirely a case of false correlation. Actually it's an artifact of semi-modern life. Remember that the transformation is selected for in case of danger; it turns out that the hormones which control this are also triggered by other forms of stress. In modern life, with monthly rents and mortgage payments, there's a monthly stress cycle. This translates into a monthly involuntary transformation cycle. 
- The small discrepancy between the average 30.4-day month and the 28.5-day lunar cycle is simply experimental roundoff error and can be ignored.