As outer forms develop, the inner consciousness also develops systematically. It could be said that the other form’s evolution is precisely tailored to accomodate the greater intensity of consciousness that is required for the next stage to manifest. Thus, as Sri Aurobindo points out, plant life and animal life share a large number of qualities based on the action of life-energy, but we see a divide due to the obvious presence and action of Mind-Energy in the animal, whether in a very rudimentary way, or, as we see in the higher animals, the action of a developed sense mind, some language skills, memory and some reasoning ability.
“Between the highest animal and the lowest man there is a still deeper though narrower gulf to be crossed, the gulf between sense-mind and the intellect: for however we may insist on the primitive nature of the savage, we cannto alter the fact that the most primitive human being has above and beyond the sense-mind, emotional vitality and primary practical intelligence which we share with the animals, a human intellect and is capable,–in whatever limits,–of reflection, ideas, conscious invention, religious and ethical thought and feeling, everything fundamental of which man as a race is capable; he has the same kind of intelligence, it differs only in its past instruction and formative training and the degree of its developed capacity, intensity and activity.”
The record is clear that various development has in fact occurred over time and that each form was not simply created by some external demiurge or God and planted here “ready made.” “It has become evident that a secretly conscious or an inconscient Energy of creation has effected the transition by swift or slow degrees, by whatever means, devices, biological, physical or psychological machinery…” We still have gaps in the evolutionary process that we cannot yet fill in; but Sri Aurobindo points out that potentially the solution to these gaps will come when we review the inner, rather than the outer, forms of development. If the real evolutionary necessity was to provide an increasingly complex form capable of manifesting the next stage of consciousness, we would not necessarily have to see a systematic step-by-step progression of outer forms; rather we could see some “leaps” in the outer form that would be consistent with the next manifested level of consciousness and its needs.
Sri Aurobindo, The Life Divine, Book 2, Part 2, Chapter 18, The Evolutionary Process — Ascent and Integration