It seems half of all humans are not spiritually developed...

[Ankh]

During the first portion of third-density cycles, incarnations are automatic and occur rapidly upon the cessation of energy complex of the physical vehicle. There is small need to review or to heal the experiences of the incarnation. As, what you would call, the energy centers begin to be activated to a higher extent, more of the content of experience during incarnation deals with the lessons of love.

Thus the time, as you may understand it, between incarnations is lengthened to give appropriate attention to the review and the healing of experiences of the previous incarnation. At some point in third density, the green-ray energy center becomes activated and at that point incarnation ceases to be automatic.

21.10 Questioner: When incarnation ceases to become automatic I am assuming that the entity can decide when he needs to reincarnate for his— the benefit of his own learning. Does he also select his parents?

Ra: I am Ra. This is correct.

21.11 Questioner: At this time in our cycle, near the end, what percentage of the entities, approximately, incarnating are making their own choices?

Ra: I am Ra. The approximate percentage is five four, fifty-four [54] percent.

As I understand this quote, it is about awakening consciousness, to do the work. We graduated to 3D, and then became self conscious. But then what? As mind/body/spirit complexes in this Octave of Choice, we are to choose a method for the Creator to know Itself, following the Law of One.

From 3D and all the way to 6,5D it is possible to choose a path of separation. In this density you are about to make this choice.

This polarity helps you to do that work in consciousness. This, in my experience, can be seen by a very little test. Look up from this screen and look at the world. Then visualize separation and observe the self during this little test. Then call upon unity in your mind and visualize unity. What do you prefer?

Anywho, my understanding is that before making this choice, one needs to have enough of the experiences upon which one can make that call. And so, here we are...

In short, I am not sure it is about being "spiritually developed"... Maybe more about being enough experienced to make a decision perhaps...? :-/