When Owen Barfield writes about 'the evolution of consciousness' - he is talking process that is driving human development.
Barfield is not, therefore, regarding consciousness is something which respond-to historical change; but the opposite. So, he is saying that it was a change in the consciousness of Western Man that drove the scientific revolution and 'materialism': first consciousness changed and then science arose...
And therefore Barfield is contradicting any idea that 'modern Man's different way of thinking is a product of the scientific revolution. He was also contradicting the idea that the change in consciousness was due to natural selection. Rather Barfield is stating that changes in consciousness have been driven-by the unfolding of a divine plan (or 'destiny') for Man.
(A plan/ destiny aiming, ultimately, at the divinisation or theosis of Man - Man becoming a god (or full Son of God, as the New Testament terms it), with a god-like way of thinking.)
The development of new forms of human thinking is something which has (again according to Barfield) happened several times in human history, and indeed prehistory. However, in the past the changes in consciousness were driven at an unconscious level and required only the passive acceptance of Men.
Currently (at least since the Romantic movement of the late 1700s), and for the first time, we are experiencing an unconscious drive towards a new kind of consciousness that will not happen unless and until it becomes conscious and chosen.
So, our current situation is that we are being driven 'instinctually' (unconsciously) towards a new consciousness / a new way of thinking. But for it actually to happen requires that we become 1. consciously, explicitly aware of what is going-on; 2. then accept this destined change, but; 3. not just accept it, because we need also to; 4. actively embrace and work-at creating this change in ourselves.
In sum; the modern situation is that we must each, personally, want-to ally our-selves with the destined change in thought and consciousness, and must make efforts to make these changes in our-selves.
Or... it will not happen; and because we cannot go-back to an earleir state of consciousness (any more than an adolescent can become an actual child again), we will remain 'stuck' in the current phase of alienated consciousness - the problems from which will continue to be cumulative.
So far, very few individuals have done this four stage process of theosis - and the great majority of people in the West remain entirely unconscious of what is going-on behind-the-scenes.
Nonetheless, at an unconscious level - the instinctive drive towards the next, and final (because divine) qualitative development of thinking continues; and leads to many undesirable outcomes.