Whenever one talks about reincarnation someone else comes with the classic question: If reincarnation exists and the spirits that discarnate and reincarnate are the same, how does one explain the increase of the world population?

This is what we will comment on.

The belief in reincarnation is one of the oldest of humanity. The first documented reference was found in an Egyptian papyrus 3,000 years BC.

Spiritism appeared in the 19th century and has come to reaffirm this belief and, in addition, to clarify the rules to which reincarnation is subjected.

We have, among Spiritism explanations, the following:

The Spirit is the intelligent principle of the universe and God created all, without exception, simple and ignorant, however with a strong desire to progress, meaning evolve.

Evolution occurs both in the material and spiritual plane. The more primitive the Spirit, the more it needs the material plane.

As a Spirit becomes purified (evolved), less it needs our material realmThe Spirit, when at the top of evolution, does not need to reincarnate anymore. They are known as pure Spirits.

As for the souls of the animals, because they are not yet developing the rational intelligence (developing only the instinctive intelligence), life on the material plane is sufficient for them. Reincarnation can be immediately (may be, does not mean it is, depends on the availability of bodies). 

There are Spirits that reincarnate immediately  

Reincarnation is a blessed opportunity due to the difficulty to do with the availability of bodies. There is no full access to reincarnation. Therefore there is queue.

There are spirits who reincarnate immediately and there are others that take ages to arrive. Normal curve (Gauss)?

There are about 3-4 disincarnate spirits for every 1 incarnate. This was revealed some time ago, when the Earth's population - number of incarnates - was about 6 billion. Therefore, the number of spirits in total would be 24 to 30 billion individuals.

The earth, by far is the only inhabited planet in the universe. As Jesus said: there are many mansions in my father's house.

A Spirit can reach any point of the universe by the speed of thought. However some regions are interdicted to the less morally advanced spirits.

When moving from one orb to another, the Spirit leaves its perispirit orb of origin, since this is made up of subtle matter, and for being matter, it is subject to the laws of physics. A perispirit in order to move, has the speed of light as limit, and can not follow the Spirit that moves at the speed of thought.  Thus, the Spirit takes in the destination orb, another perispirit with the nature of matter of there. 

A Reincarnation cycle would be 280 years 

Hence we can draw some conclusions which are: 

• Average time between two incarnations:

At the beginning of evolution, Homo sapiens, for being too close to an animal, could reincarnate immediately. Therefore, if there were full accessibility to bodies, their time on the spiritual plane, between incarnations, would be close to zero. 

At the end of the scale of evolution for the pure Spirits, the time between incarnations is infinite.

• Reincarnation Cycle:

A 4:1 ratio is only valid for the point of the evolutionary scale we are in, so if life expectancy at this point is 70 years, a Spirit waits on average 280 years in discarnate state in order to have to reincarnate for a lifespan of about 70 years.

This totals 280 years between the states of discarnate and incarnate, which we call reincarnation cycle.

The time of the evolutionary need and the waiting queue due the lack of full accessibility of bodies are summed in this period of time of 280 years.

In order to simplify the model, we now assume that accessibility is fully available and so the 280 years is our current average for a cycle (to incarnate and to discarnate).

This average is similar to the average of a normal curve (Gaussian) and thus in the extremities of the curve there will be a small percentage of the Spirits who reincarnate almost immediately, and another that takes much longer than average. There will also be a very large number of intermediate points. 

Evolution takes place in small steps 

In year 1 of the Christian era (birth of Jesus), according to an article published in Época magazine of June 6, 2011, we were 300 million incarnated spirits.

Assuming that the time of a discarnate Spirit was the same as for an incarnate one (ratio 1:1) and still maintaining full accessibility to bodies, the total number of the planet Spirits was 600 million.

If life expectancy was 35 years, one reincarnation cycle lasted 70 years.

If we keep the current reincarnation cycle of 280 years and add a limitation of accessibility to bodies, this number could be increased by four times (4 = 280/70) which increases the total number of Spirits to 2.4 billion. That is, 10% of the 24 billion above.

To close the sum, a reincarnation cycle should be 2,800 years, which would mean that there may be even Spirits from the time of Jesus still to reincarnate.

We arrived here to an absurdity, by simply comparing the degree of civilization of a man of that era with today’s. Nonsense as this represents a huge leap in evolution, a fact that according to Spiritism teaching does not occur.

Evolution occurs in small steps, subject, however, to a law of exponential growth, as it began to occur in the last three centuries.

The mentioned magazine article brings data about the global population from 200,000 years BC. 

Spirits that migrated from other orbs towards Earth 

The following is the summary:Year 200.000 B.C. - 10.000 (Homo sapiens)

Year 10.000 B.C. - 1 million (begining of agriculture)

Year 1 – 300 million (begining of Christian Era)

Year 1.000 A.D. – 310 million

Year 1.500 A.D. – 500 million

Year 1.801 A.D. - 1 billion

Year 1.900 A.D. – 1.7 billion

Year 2.000 A.D. – 6 billion

Year 2.011 A.D. - 7 billion

If we compare year 1 to year 1800 (19^th century), when Earth's population was 1 billion of incarnated spirits, the calculations become are now acceptable.

So for the past three centuries there must have been migration of Spirits from other parts of the universe to Earth.

On the other hand, if we compare year 1 with year 1800, this need for migration is tightly reduced. Therefore acting only on the parameters of reduced waiting time, average life expectancy and average time on the spiritual plane (erraticity), the incarnate population growth seems reasonable. 

We had great leaps in centuries 19^th, 20^th and 21^st. The 19^th century was marked by the beginning of the expansion of knowledge; the 20^th century by growth of the industry and the 21^st century by technology. 

To evolve is similar to make fudge 

In order to make fudge (which tastes so good!) one must get to the right consistency. Let's pretend that evolution is like making fudge... When a planet moves from one category to another (from primitive to a level of test and atonement and then to regeneration level), it is because it has reached the point.

Thus, from century 1 to17, evolution did not have occur through great leaps and there was very little change and our orb was, so to speak, cooking the Spirits that lived here almost in a closed evolutionary cycle system, without much migratory interaction with other orbs.

At the end of the 18^th century we were coming up towards the point of getting a glimpse of a shift from a world of test and atonement into regeneration.

To get to this point, we took two thousand centuries (200,000 years), counting from the event of Homo sapiens. If we were to count from the beginning of the formation of the Earth, it would already be 45 million of centuries or 4.5 billion years.

If it is “cooked” for 2000 and 45 million centuries then it is coming up to the right moment (or right consistency in the analogy to milk candy), only in 2 centuries ahead this point will be a very rare event. This moment in time should be made use of by those who are already in condition to do so. Like the Earth, many other worlds are also cooking, but without going so far as whole or getting to the right “point” or “consistency”.

The Spirits who arrive alone "to the point" (minority of the upper arm of the normal curve) have to migrate to another orb where the average is now at the point. As our Earth is coming "to the point or consistency", many of them have come here.

The Spirits' Book explains that a spirit can migrate to any point in the universe at the speed of thought. To this end it leaves its perisprit in the orb of origin and takes another perisprit in the orb of destination, now with the matter from there. 

The so called Adamic race came form another orb 

This happened with that which Spiritism calls members of the Adamic race, when those Spirits came here, from another orb, at the time that orb was moving from primitive world to tests and atonement. ⁽¹⁾

It is few Spirits from many orbs, which in the sum makes up a lot.

Now in the 21^st century, other Spirits who are coming from more evolved orbs are being added to these spirits here to help in the transition process that has already begun.

Thus, this increase in mass of Spirits is explainable and should be reduced when the passing of a world of test and atonement to a world of regeneration is finalized, because the Spirits who remain in the lower arm of the normal curve have not reached "the point".They will have to leave to another world that is still in the level of test and atonement, or just entering into that level.

If the majority of the Spirits who are flocking here comes from a world of tests and atonement, as an opportunity to improve, a minority come from more advanced worlds, already at the stage of regeneration, to assist us in this transition.

These spirits added to those who are from Earth itself, and who have already reached the tip of the upper arm of the normal curve, are the missionaries of this transition that we are now experiencing, as mentioned in Revelation, one of the books that comprise the New Testament.

⁽¹⁾ Kardec teaches that Adamic race came from another orb about 6000 years ago, but does not name the planet. There are other authors who teach that the Adamic race belongs a evolutionary system  called Capela, which is composed of a certain amount of orbs and this migration took place thousands of years. The difference between Kardec and these is in the name of and location of the point of origin as well as the time that it took place, not the fact itself.

The common to both is the fact that another orb, not Earth, moved over from the category of worlds of test and atonement to become a world of regeneration.

When this took place, some spirits had no evolutionary conditions to remain there and had to be removed. Soon, there were exiles. These spirits came to our earth, which at the time was evolving from a Primitive world of Primal towards a world of test and atonement.

There is also the belief that these spirits who were exiled here received the designation as Adamic race, and the sense of Lost Paradise refers to the world from which they demoted from.

Can Earth today, when compared with itself at the time it was primitive, not be considered a paradise?