So i guess we arrive at what was always the issue, namely if the psyche=body (for it is not only the brain) or not.
I would not have a problem with this tautology, if it could be presented just why man is as complicated if he is just another basic brute from nature's viewpoint, or even some freak accident.
Mind you, if i really wanted to type something implausible, i could say that the mind is so complicated that, like a star, upon its death energy is bound to transform to something else

But for the time being i will contend that even if the mind (and rest of the body) = man, then it seems that nature either did not compute anything correctly (man is known to be the sole creature that can commit suicide, for example) or that it might have had some other plan too. Remember Alpha Centauri
To get back on topic: when i was still a student of philosophy i had thought a great deal about the brain-psyche issue. But it seems to me that it is hard enough to speak of the brain's functions as something that actually belongs to us, in the sense that we control them. It seems that the vast majority of what is going on in the brain is either not conscious, or is partly conscious. If you think of it you might even argue that our own thoughts are not exactly ours, since we appear to be the person steering the wheel in this boat, but the rest of the boat, although by name it belongs to us, is an utterly different substance. Likewise our thoughts come and go like clouds on a stormy day, and clouds were a strange spectacle from men of old ages who could not say what they were. Likewise we are primitives in relation to self-reflection and how the brain works.
So it would seem that, partly at least, we should not speak so adamantly about a mechanism (the body-brain) that we have yet to know in any real, deep manner.