I think that a more precise definition of your brain = behavior assertion is necessary before I can agree or disagree. There are several possible philosophical routes that one may take and still be in keeping with the brain/behavior idea. There is materialism, or the idea that there is no consciousness or mind to interfere with behavior that is produced by the brain. There is epiphenomenalism, or the idea that the brain produces the mind as a sort of by-product, but that the mind cannot influence the brain.
Then there are further positions that have been taken by various historical figures that are less in keeping with the brain = behavior concept (otherwise known as the Principle of Uniformity of Causality): interactionism, which allows for the mind and the body to influence each other; dual-action monism, which considers the mind and body to be akin to two sides of the same coin, operating as a single process; psychophysical parallelism, which retains the separateness of the mind and body but asserts that they work in parallel fashion; and even occasionalism, or the idea that neither the mind or body control anything because God is the ultimate cause.
Interactionism has a certain evolutionary validity in terms of the potential usefulness of consciousness. Consciousness would seemingly allow an animal to act more adaptively to novel and/or surprising circumstances. Natural selection, which is by nature a very slow process, would be inadequate as an adaptive mechanism in such cases.
Pardon the philosophy lesson, but I think it is useful to see that there is an entire range of possibilities to consider.
Entirely appropriate. Is a question lots of people have thought about over long period of time. Of course. All of the characterizations in your second paragraph are forms of dualism, ruled out in my assertion. And by the suggestion that "mind" is actually a part of the brain, I exclude epiphenomenonalism as well as completely reductive materialism. Now, with the terms straight, what do you think of the assertion? PG