The Earth's population continues to grow. Will there come a day when there will be more space and/or food for everyone? (The Spirits’ Book Q. 686)
         No, because God provides everything and maintains the balance. Life on Earth would not exist without the reproduction of the species (animal, plant and human). There are, however, things we still do not understand since we are still imperfect spirits.

          Will the human race cease to exist on Earth in the future? (The Spirits’ Book Q.689)
         Yes, the human race will be replaced by more evolved races, which will descend from the current race. This is due to the spiritual evolution that is taking place slowly. These may be the same spirits that inhabit the Earth today, but more advanced now reincarnating in bodies best suited to their evolution.

          What distinguishes the primitive human beings from todays? (The Spirits’ Book Q.691)
         The primitive human beings had physical strength and instinct as main characteristics, while the races today use more intelligence than physical strength. We also accomplish more things in the exact extent that we evolve spiritually.

          It is correct to try to work on improving the animals and the plants through science? (The Spirits’ Book Q.692)
         Human efforts to make discoveries that improve the quality of life of humans, animals and plants are not contrary to natural laws, nor were at any time. But one should not harm nature. Intelligence should be used with love, without causing suffering to those species, respecting all life forms. Life only belongs to God.

          Can humans regulate the reproduction of living beings, avoiding excessive in number? (The Spirits’ Book Q. 693 issue - a)
         You can adjust reproduction, but not by vanity or selfishness. It should not, however, impede the reproduction, committing abuses. Animals and plants have their own way to provide the balance of nature. Thus, for example, when many plants are planted in a small space, they do not grow freely, but atrophy. This is God’s law in action.

          The custom of marriage, i.e., of human beings to unite in lasting relationships with the objective of constituting a family, can be considered a kind of progress? (The Spirits’ Book Q. 696)
         Yes, because the termination of marriage would be a setback, where respect and mutual collaboration in the family would be lacked.

          Can Spiritists divorce? Why? (The Spirits’ Book Q. 697)
         Yes, they can get divorced. Separating what is not really united by harmony, love and respect can be a solution not to acquire new problems. It must not, however, be the solution sought whenever there is conflict between the couple. There should be an effort to develop ties of fraternity and respect in relationships.

          What is celibacy? When does it have value before the Divine laws? (The Spirits’ Book Q.698 and 699)
         Celibacy is when a person remains unmarried. This choice only has value before God's laws if it is meant to work in favour of others, or is a test chosen by the Spirit. What matters is the intention; the reason why the person chose this lifestyle.

          What is polygamy? What about monogamy? Which one is according to the God’s laws? (The Spirits’ Book Q. 701)
         Polygamy is the marriage of an individual with several others, simultaneously. Monogamy is the rule, custom or practice socially regulated according to which a person (man or woman) can not have more than one husband or wife. The extinction of polygamy is a social progress. While in polygamy prevails sensuality, in monogamy the couple should develop mutual affection.