It is being said that aatma is there in all of our body and it is immortal... My question is Aatma can breed?? If no, then why the population of the world is increasing day by day. Thank you brother for asking such a wonderful question. Those who do not know about atman and read about reproduction ask this type of question. First of all you should understand what atman is: atman is one's True Self, "generally translated into English as Self", beyond identification with the phenomenal reality of worldly existence. Just as a man living in a house is called a householder, atman (meaning “Self within”) living in a human body is called an individual. When this “human house” becomes old and irreparable, atman leaves the house and we say that the individual has died. If atman is brahman in a pot (the body), then one need merely break the pot to fully realize the primordial unity of the individual soul with the plentitude of Being that was the Absolute. In the Brihadaranyaka Upanishad, uses the word to indicate that in which everything exists, which is of the highest value, which permeates everything, which is the essence of all, bliss and beyond description. Taittiriya Upanishad defines atman or the Self as consisting of five sheaths (kosha): the bodily self consisting the essence of food (annamaya kosha), the vital breath (pranamaya kosha), the mind or will (manomaya kosha), the intellect or capacity to know (vijnanamaya kosha) and bliss (anandamaya kosha). Pañcadaśī classifies the degrees of atman under three headings: Gauna or secondary (anything other than the personality that an individual identifies with), Mithya or false (bodily personality) and Mukhya or primary (the real Self). So we are we are the atman, not the physical body, emotions, external mind or personality. Each human being, regardless of religion, geographic region, gender, color or creed is in reality atman clothed in a physical body. Since atman is inherently pure and divine, every human being is potentially divine. A man is not born a sinner, but becomes a victim of ignorance under the influence of cosmic ignorance, called Maya. Just as darkness quickly disappears upon the appearance of light, an individual’s delusion vanishes when he gains self-knowledge. - Human Being are made up of various sharira ("bodies") such as sthula-sharira (gross body), sukshma-sharira (subtle body), karana-sharira (causal body) and within these shariras resides the atman (True Self). In human being all three shariras (bodies) exist simultaneously, but our recognition of them will vary greatly depending on the individual's state of awakening. - The atman that resides in human were once lower species, then plants, then animals, and finally human beings. - Human Beings are the highest evolved physical creatures in the universe. - The atman reincarnate from human body to human body until it become "liberated" from samsara (the wheel of rebirth). - The liberation of the atman from samsara (the wheel of rebirth) is called moksha or "mukti" ("liberation"). So from above we can conclude that:: - Atman is uncreated, immortal and divine. - Although Atman is generally translated as soul or spirit, Atman and soul do not mean the same. - Atman has two states of existence, liberated and bound. - In the human body, Atman is deluded by cosmic ignorance, called Maya in Sanskrit. - There are various viewpoints regarding relationship of the liberated Atman with Brahman. - An individual is not born a sinner, but commits sin under the influence of Maya. Thus, the purpose of Hindu religious life is to transcend Maya. Now from Bhagwat Gita Chapter 2 : 18. These bodies of the embodied Self, which is eternal, indestructible and immeasurable, are said to have an end. Therefore, fight, O Arjuna! 19. He who takes the Self to be the slayer and he who thinks He is slain, neither of them knows; He slays not nor is He slain. So, Atman cannot be divided nor it breeds nor it dies nor reproduce nor it can be cut into pieces. As you said population is increasing, correct is population of Human being is increasing. You can see many other species become extinct and many other are endangered it means more and more atman are evolving to human beings according to their karmas. It is simple logic. Once to karma is fulfilled from one species the atman goes to higher species. The last highest species is Human being so that more and more atman are merging to human beings. Do not mix body with atman, atman is not body. Body dies but atman not.