All that follows is opinion. Based on my own thoughts, experiences and studies. It is not meant to be taken as the gospel, I do not claim to know
the gospel.
My opinion is that what the author called the "bicameral mind" never disappeared, or even lessened in the population. It was there, and it is still
there. It is not "dormant," it is "distracted" or "overridden."
I also opine that what the author calls "consciousness" mystics would call the "Ego." (Very different from the Ego as used by psychologists, who
feel the Ego is "normal" and adaptive/positve. I am using the term "Ego" as a less positive thing, common, and thus normal, but not desirable.
Mystics would call the "bicameral mind" consciousness, and would find that more desirable. (If one could "desire" from consciousness)
I would say that what happened was not a breakdown, or doing away with of this "bicameral mind" but rather a "drowning out" of it by a newer,
louder voice, the voice of the "Ego" or mind.
I would also suggest that if schizophrenia is related at all to the bicameral mind and not a wholly different thing, schizophrenia is not someone who
has an active bicameral mind and others do not, but rather someone who has not completely overridden the bicameral mind, (there are gaps in the Egoic
construct) BUT who chooses to try to interpret the data from the bicameral mind through the lens of the Ego.
I would argue that a Mystic has the same gaps in the Egoic construct, and receives information via the consciousness or bicameral mind, but when doing
so "relaxes" the Egoic lens and allows the information to flow without attempting to first force it through the Egoic lens or filter. My feeling
would be that the attempt to force this "intuitive knowing" through the filter of Mind or Ego is the part that is problematic, not the intuitive
knowing itself.
I do not agree with his time frame, I do not think it (the takeover by the Ego) was that recent. I think one could safely assume by the time the
writing of the Illiad occurred, most people were living primarily from the Ego perspective. Hero's and Kings, and common men in heroic
circumstances, (going into battle) are described as having this ability to hear the Gods. I would say not much has changed since then.
If one wanted to "look" historically for a time frame, one could probably use the development of agriculture as the most recent possible date for
the takeover by the Ego or Mind or Individual Identity, and likely it occurred sooner, and then technology developed that we could "see"
historically. Agriculture requires planning, it requires an ability to predict into the future from knowledge of the past. Organized hunting to some
degree does as well, but it is harder to date. However, even using agriculture we are left with a date of around 10,000 years ago.
I do agree that the process by which the Egoic mind drowned out the Consciousness or bicameral mind may have been a progressive one, much as we can
see occur in little children as they develop from infancy to childhood as they form their identities and idea of "self." This is why I feel it had
to have occurred prior to the development of agriculture. By the time that "symptom" would appear, the progression would be well underway.
I do think the "tool" of the Egoic mind is handy. And clearly adaptive in the short run. I feel that the ideal circumstance would not be a
subjugation of the Consciousness to Mind, but a dominance of Consciousness with the use of mind as a tool. That the Egoic mind is best considered
servant, not master. I think calling the game early by lauding the superiority of the Egoic mind over the bicameral mind is unwise. Although it has
allowed a lot of things to occur, not all of them are positive, and in fact, with so many very unhappy people and an environment in a state of
collapse, one could argue that the Egoic mind will harm us more than help us in the long run unless we can restore the balance between the
Consciousness and the Egoic mind.
Also, I think that the story of the fall from grace and the eviction from the garden of Eden is a mythologized version of this happening.
If read
from that point of view, it makes an interesting supplement to this topic. The Creation Hymn of the Rig Veda also describes something similar.