^{P565:2, 49:5.1} It will be somewhat difficult to make an adequate portrayal of the planetary series of mortals because you know so little about them, and because there are so many variations. Mortal creatures may, however, be studied from numerous viewpoints, among which are the following:

1. Adjustment to planetary environment.
2. Brain-type series.
3. Spirit-reception series.
4. Planetary-mortal epochs.
5. Creature-kinship serials.
6. Adjuster-fusion series.
7. Techniques of terrestrial escape.

^{P565:11, 49:5.3} 1. Adjustment to planetary environment. There are three general groups of inhabited worlds from the standpoint of the adjustment of creature life to the planetary environment: the normal adjustment group, the radical adjustment group, and the experimental group.

^{P565:12, 49:5.4} Normal adjustments to planetary conditions follow the general physical patterns previously considered. The worlds of the nonbreathers typify the radical or extreme adjustment, but other types are also included in this group. Experimental worlds are usually ideally adapted to the typical life forms, and on these decimal planets the Life Carriers attempt to produce beneficial variations in the standard life designs. Since your world is an experimental planet, it differs markedly from its sister spheres in Satania; many forms of life have appeared on Urantia that are not found elsewhere; likewise are many common species absent from your planet.

^{P565:13, 49:5.5} In the universe of Nebadon, all the life-modification worlds are serially linked together and constitute a special domain of universe affairs which is given attention by designated administrators; and all of these experimental worlds are periodically inspected by a corps of universe directors whose chief is the veteran finaliter known in Satania as Tabamantia.

^{P566:1, 49:5.6} 2. Brain-type series. The one physical uniformity of mortals is the brain and nervous system; nevertheless, there are three basic organizations of the brain mechanism: the one-, the two-, and the three-brained types. Urantians are of the two-brained type, somewhat more imaginative, adventurous, and philosophical than the one-brained mortals but somewhat less spiritual, ethical, and worshipful than the three-brained orders. These brain differences characterize even the prehuman animal existences.

^{P566:2, 49:5.7} From the two-hemisphere type of the Urantian cerebral cortex you can, by analogy, grasp something of the one-brained type. The third brain of the three-brained orders is best conceived as an evolvement of your lower or rudimentary form of brain, which is developed to the point where it functions chiefly in control of physical activities, leaving the two superior brains free for higher engagements: one for intellectual functions and the other for the spiritual- counterparting activities of the Thought Adjuster.

^{P566:3, 49:5.8} While the terrestrial attainments of the one-brained races are slightly limited in comparison with the two-brained orders, the older planets of the three-brained group exhibit civilizations that would astound Urantians, and which would somewhat shame yours by comparison. In mechanical development and material civilization, even in intellectual progress, the two-brained mortal worlds are able to equal the three-brained spheres. But in the higher control of mind and development of intellectual and spiritual reciprocation, you are somewhat inferior.

^{P566:4, 49:5.9} All such comparative estimates concerning the intellectual progress or the spiritual attainments of any world or group of worlds should in fairness recognize planetary age; much, very much, depends on age, the help of the biologic uplifters, and the subsequent missions of the various orders of the divine Sons.

^{P566:5, 49:5.10} While the three-brained peoples are capable of a slightly higher planetary evolution than either the one- or two-brained orders, all have the same type of life plasm and carry on planetary activities in very similar ways, much as do human beings on Urantia. These three types of mortals are distributed throughout the worlds of the local systems. In the majority of cases planetary conditions had very little to do with the decisions of the Life Carriers to project these varied orders of mortals on the different worlds; it is a prerogative of the Life Carriers thus to plan and execute.

^{P566:6, 49:5.11} These three orders stand on an equal footing in the ascension career. Each must traverse the same intellectual scale of development, and each must master the same spiritual tests of progression. The system administration and the constellation overcontrol of these different worlds are uniformly free from discrimination; even the regimes of the Planetary Princes are identical.

^{P566:7, 49:5.12} 3. Spirit-reception series. There are three groups of mind design as related to contact with spirit affairs. This classification does not refer to the one-, two-, and three-brained orders of mortals; it refers primarily to gland chemistry, more particularly to the organization of certain glands comparable to the pituitary bodies. The races on some worlds have one gland, on others two, as do Urantians, while on still other spheres the races have three of these unique bodies. The inherent imagination and spiritual receptivity is definitely influenced by this differential chemical endowment.

^{P566:8, 49:5.13} Of the spirit-reception types, sixty-five per cent are of the second group, like the Urantia races. Twelve per cent are of the first type, naturally less receptive, while twenty-three per cent are more spiritually inclined during terrestrial life. But such distinctions do not survive natural death; all of these racial differences pertain only to the life in the flesh.

^{P567:1, 49:5.14} 4. Planetary-mortal epochs. This classification recognizes the succession of temporal dispensations as they affect man's terrestrial status and his reception of celestial ministry.

^{P567:2, 49:5.15} Life is initiated on the planets by the Life Carriers, who watch over its development until sometime after the evolutionary appearance of mortal man. Before the Life Carriers leave a planet, they duly install a Planetary Prince as ruler of the realm. With this ruler there arrives a full quota of subordinate auxiliaries and ministering helpers, and the first adjudication of the living and the dead is simultaneous with his arrival.

^{P567:3, 49:5.16} With the emergence of human groupings, this Planetary Prince arrives to inaugurate human civilization and to focalize human society. Your world of confusion is no criterion of the early days of the reign of the Planetary Princes, for it was near the beginning of such an administration on Urantia that your Planetary Prince, Caligastia, cast his lot with the rebellion of the System Sovereign, Lucifer. Your planet has pursued a stormy course ever since.

^{P567:4, 49:5.17} On a normal evolutionary world, racial progress attains its natural biologic peak during the regime of the Planetary Prince, and shortly thereafter the System Sovereign dispatches a Material Son and Daughter to that planet. These imported beings are of service as biologic uplifters; their default on Urantia further complicated your planetary history.

^{P567:5, 49:5.18} When the intellectual and ethical progress of a human race has reached the limits of evolutionary development, there comes an Avonal Son of Paradise on a magisterial mission; and later on, when the spiritual status of such a world is nearing its limit of natural attainment, the planet is visited by a Paradise bestowal Son. The chief mission of a bestowal Son is to establish the planetary status, release the Spirit of Truth for planetary function, and thus effect the universal coming of the Thought Adjusters.

^{P567:6, 49:5.19} Here, again, Urantia deviates: There has never been a magisterial mission on your world, neither was your bestowal Son of the Avonal order; your planet enjoyed the signal honor of becoming the mortal home planet of the Sovereign Son, Michael of Nebadon.

^{P567:7, 49:5.20} As a result of the ministry of all the successive orders of divine sonship, the inhabited worlds and their advancing races begin to approach the apex of planetary evolution. Such worlds now become ripe for the culminating mission, the arrival of the Trinity Teacher Sons. This epoch of the Teacher Sons is the vestibule to the final planetary age -- evolutionary utopia -- the age of light and life.

^{P567:8, 49:5.21} This classification of human beings will receive particular attention in a succeeding paper.

^{P567:9, 49:5.22} 5. Creature-kinship serials. Planets are not only organized vertically into systems, constellations, and so on, but the universe administration also provides for horizontal groupings according to type, series, and other relationships. This lateral administration of the universe pertains more particularly to the co-ordination of activities of a kindred nature which have been independently fostered on different spheres. These related classes of universe creatures are periodically inspected by certain composite corps of high personalities presided over by long-experienced finaliters.

^{P568:1, 49:5.23} These kinship factors are manifest on all levels, for kinship serials exist among nonhuman personalities as well as among mortal creatures -- even between human and superhuman orders. Intelligent beings are vertically related in twelve great groups of seven major divisions each. The co-ordination of these uniquely related groups of living beings is probably effected by some not fully comprehended technique of the Supreme Being.

^{P568:2, 49:5.24} 6. Adjuster-fusion series. The spiritual classification or grouping of all mortals during their prefusion experience is wholly determined by the relation of the personality status to the indwelling Mystery Monitor. Almost ninety per cent of the inhabited worlds of Nebadon are peopled with Adjuster-fusion mortals in contrast with a near-by universe where scarcely more than one half of the worlds harbor beings who are Adjuster-indwelt candidates for eternal fusion.

^{P568:3, 49:5.25} 7. Techniques of terrestrial escape. There is fundamentally only one way in which individual human life can be initiated on the inhabited worlds, and that is through creature procreation and natural birth; but there are numerous techniques whereby man escapes his terrestrial status and gains access to the inward moving stream of Paradise ascenders.