No, the soul’s evolution is always forward. There is no retrogression as is commonly preached. In fact, the soul is not shifting passively from one body to another on the basis of karma and the consequent reward and punishment. That would be quite a meaningless machinery. Karma is a learning evolutionary process through which the soul evolves from its seed state towards the manifestation of the divinity inherent in it. Except for the very primitive earliest human births, when it is possible to slip back to an animal state, it is just impossible to go back to the previous stages. The body and mind are the instruments of a developing soul that begins to use thought and speech to express itself. An animal consciousness and animal nature and body cannot support even a reasonably developed soul. Of course, there are some human beings in whom the soul is largely asleep and hence their nature is often crude and animal-like or even worse. But that is a different story.
Affectionately,
Alok Da
