... consciousness is absolutely necessary for the animation of the body, but what is this consciousness?
Neemai, I think it is inaccurate to say that consciousness is necessary for the animation of the body. I suspect that consciousness emerged fairly high up the animate trunk of life.
Consciousness is not necessary for life. Plants do quite well without it (at least in a form we probably all agree we're familiar with). Bacteria and viruses are almost certainly not conscious, any more than a calculator is conscious.
Doug Hofstadter, in his excellent book
I Am a Strange Loop, doubts that mosquitoes are conscious. I'm not sure.
I think that for a clue to what consciousness is, we need to meditate on Dumbledore's remark to Harry that it is not our capabilities that make us what we are, but our choices.
Whatever consciousness is, whatever choice is, they go together.
Bacteria and mosquitoes react to their environment. They behave in certain predictable, and sometimes deadly ways when confronted with certain situations. But they don't choose that behavior any more than a calculator "chooses" to display 4 when you enter 2, plus and 2.
In order to survive animals have to procreate, sustain themselves, and avoid threats. Plants and lower animals have to do the same of course, but their fitness for survival seems to depend entirely on statistical probabilities. Individual plants "lucky" enough that their seeds fall on fertile soil that doesn't lie in the path of a migrating dinosaur herd or wildfire will have descendants; those that don't won't.
Animals of higher orders (and where the line is between higher and lower is certainly a matter of debate) choose because they have as individuals a measure of control of their individual fate and that of their descendants (i.e., whether they have any). If eating, breeding, fighting and fleeing were unrelated activities that normally had no effect on one another, they could have been managed by simple, unconscious reflex mechanisms. But they are not. The environmental and internal factors that determine the probable impact of those behaviors on survival are complex and subtle. Nature never discovered a working algorithm for simple reflex action governing all of those behaviors in complex animals. Instead nature gave higher animals the power to choose whether to eat, breed, fight or flee. Those that chose well survived more than those that didn't. Millennia of evolution refined that capability in some animals to the ability to choose between an iPod and a Trea.
In order to choose well, animals needed an integrated model of everything they could learn about all the factors affecting their choices. Consciousness is that model. It is by consciousness that an animal is aware that an object in its field of vision is at one and the same time a potential food source, a potential competitor for a food source, a potential mate, and a potential threat. Only by recognizing that one and the same object is in the condition-set for many different behaviors can the animal learn to decide among those behaviors.
Just as heat or smoke are symptoms of fire, so is consciousness a symptom of the soul? Is it in fact, consciousness, that proves that the soul is present?
The above evolutionary explanation of consciousness only explains why animals, and by extension people, are conscious. If by "soul" you mean to imply something "inside" the animal or "inside" the person, this argument will not help.
Conscious behavior, is just that: behavior. It is process, not thing. And the participants in that process involve not just the brain but every part of the body.
Indeed, I think the dichotomy between body and mind or between body and soul is a false one. The body is not mere inert matter to be acted upon by mind; some bodies (yours and mine, certainly) are active and conscious. Minds and souls are not pure spirit, but the activity of bodies that have evolved in the right way.
Moreover, I think there's very good reason to believe that the way my mind (soul) works is very closely tuned to the detail of the way my body works. Without my body, I wouldn't be me.
Namiste.