Question: In the beginning of the century, there were not 6 billion people on this planet, but now there are. So how can reincarnation explain this, if by reincarnation, we mean that a soul leaves the mortal body and enters another?
Thank you for writing with your question.
There are a total of 8,400,000 species of bodies that the soul may occupy. It is not that the soul will only enter into another human body. It may occupy any of the 8,400,000 species acording to its overall consciousness at the time of death. Though there may have been less humans on earth 100 years ago, we cannot count how many ants, pigs, dogs, and trees there were at that time compared to now. Thus such an analysis is futile, as measuring the existence of life is beyond the conception of man.
Sometimes one species may be predominant, and at other times it may be another species. This just reflects the overall sum consciousness of the universe.
We must also keep in mind that there are countless planets, and countless universes as well. The soul may attain a destination beyond this earthly planet, and souls from other realms may return to the earth planet. When we take into account all of these factors, the variation in population of a particular species over time becomes easy to understand.