@Parapraxis,
It's probably very likely that Descartes too believed that the mind was part of the brain.
Meditations is essentially a thought experiment using scientific reasoning (i.e. doubt everything, analyze into clear and distinct ideas, reconstruction of said ideas, and enumeration). Keep in mind that Descartes was a
renaissance man in most senses of the term. On top of being a philosopher, he was also a soldier, a mathematician, a lawyer, a composer, and also an amateur biologist. It was during this time as a soldier (which gave him considerably long periods of down time) that he engaged in studies of anatomy and biological science.
Descartes dualism (mind and matter, Res cogitans and Res extensa) is dependent on logical inference and deduction for the most part. This is, I would assume, just an established clear and distinct idea. I don't think we would want to hang our beliefs nowadays on formal, objective, and eminent realities. But I have been of the opinion that Descartes posits the material world in some respects because he needed it to validate the scientific processes he utilized throughout
Meditations? it seems only practical. In this way, Descartes could then know what tests to create and corrections to make.
But there is nothing really
biologically concrete in his theory except for a few conclusions he came up with as an amateur biologist. Descartes, being a mathematician was very concerned with mathematical (geometrical) certainties. Look at
mediation 1 for example to see how mathematical certainties are in some ways immune to doubt. Descartes, being a biologist as well, noticed that most things in the body (well, cows for the most part) came in pairs of twos (thus his mathematics). In his studies though, there was one thing (for Descartes) that did not come in a pair? the cannarium, or what we know today as the pineal gland. This is where Descartes thought would be the most ideal point at which the mind interacts with the body. But this just seems to be practical connection rather than anything else.
So I would assume that psychology would be your best bet for analyzing Descartes in a wide degree. If you were to research more on your topic, maybe you would want to look up theories about the nervous system and stuff like that. Descartes, from as far as I can tell, identified a
hardwire connection in the pineal gland. This in connection to Descartes arguments would be hard to pin. I think you would have trouble finding consistent evidence in
Mediations, Principles of Philosophy, or
Discourse on Method.
That being said, your research on how consciousness comes through our genes is interesting. You could talk about Descartes and his theory of innate ideas, the notion that what we know comes before the senses?"a-priori." If genes hold some deterministic values for us, then the theory of innate ideas may hold water. John Locke's first goal in
Essay concerning human understanding is to disprove the notion of innate idea, thus proving empiricism rather than rationalism as the logical choice. Empiricism is of course the flavor of the last few centuries, so I would think it would be interesting to see some confrontation to empirical thought in an empirically validated "innate" notion.