The law of karma as part of a process of soul evolution and development can only have meaning if it is continuous and follows the line of development. This implies that it is active in the pre-human evolutionary stages as well as in the human and beyond. This then implies that the soul exists, not only as a unique “creation” dropped into human life, but in the pre-human evolutionary stages as well. It appears that the soul develops and evolves in sync with the external evolutionary development.
Sri Aurobindo discusses the issue: “Because soul or spirit works in the animal on a lower scale, we are not warranted in thinking that there is no soul in him, any more than a divine or superhuman being would be justified in regarding us as soulless bodies or soulless minds because of the grovelling downward drawn inferiority of our half-animal nature.”
“The spiritual law of Karma is that the nature of each being can be only the result of his past energies; to suppose a soul which assumes and continues a past karma that is not its own, is to cut a line of dissociation across this law and bring in an unknown and unverified factor. But if we admit it, we must account for that factor, we must explain or discover by what law, by what connection, by what necessity, by what strange impulsion of choice a spirit pure of all animal nature assumes a body and nature of animality prepared for it by a lower order of being. If there is no affinity and no consequence of past identity or connection, this becomes an unnatural and impossible assumption. Then it is the most reasonable and concordant conclusion that man has the animal nature…because the developing self in him like the developed body has had a past subhuman evolution. This conclusion preserves the unity of Nature and its developing order; and it concurs with the persistent evidence of an interaction and parallelism which we perceive between the inward and the outward, the physical and the mental phenomenon….”
“…it makes soul or spirit, no longer a miraculous accident or intervention in a material universe, but a constant presence in it and the secret of its order and its existence.”