As stated in Bhagavad-gītā (7.27):

“O scion of Bharata [Arjuna], O conqueror of the foe, all living entities are born into delusion, overcome by the dualities of desire and hate.” This is an explanation of how the living entity falls down into this material world. In the spiritual world there is no duality, nor is there hate. The Supreme Personality of Godhead expands Himself into many. In order to enjoy bliss more and more, the Supreme Lord expands Himself in different categories. As mentioned in the Varāha Purāṇa, He expands Himself in viṣṇu-tattva (the svāṁśa expansion) and in His marginal potency (the vibhinnāṁśa, or the living entity). These expanded living entities are innumerable, just as the minute molecules of sunshine are innumerable expansions of the sun. The vibhinnāṁśa expansions, the marginal potencies of the Lord, are the living entities. When the living entities desire to enjoy themselves, they develop a consciousness of duality and come to hate the service of the Lord. In this way the living entities fall into the material world. In the Prema-vivarta it is said:

The natural position of the living entity is to serve the Lord in a transcendental loving attitude. When the living entity wants to become Kṛṣṇa Himself or imitate Kṛṣṇa, he falls down into the material world. Since Kṛṣṇa is the supreme father, His affection for the living entity is eternal. When the living entity falls down into the material world, the Supreme Lord, through His svāṁśa expansion (Paramātmā), keeps company with the living entity. In this way the living entity may some day return home, back to Godhead.

By misusing his independence, the living entity falls down from the service of the Lord and takes a position in this material world as an enjoyer — that is to say, the living entity takes his position within a material body. Wanting to take a very exalted position, the living entity instead becomes entangled in a repetition of birth and death. He selects his position as a human being, a demigod, a cat, a dog, a tree, etc. In this way the living entity selects a body out of the 8,400,000 forms and tries to satisfy himself by a variety of material enjoyment. The Supersoul, however, does not like him to do this. Consequently, the Supersoul instructs him to surrender unto the Supreme Personality of Godhead. The Lord then takes charge of the living entity. But unless the living entity is uncontaminated by material desires, he cannot surrender to the Supreme Lord. In Bhagavad-gītā (5.29) the Lord says:

“The sages, knowing Me as the ultimate purpose of all sacrifices and austerities, the Supreme Lord of all planets and demigods and the benefactor and well-wisher of all living entities, attain peace from the pangs of material miseries.”

The Supreme Lord is the supreme friend of everyone; however, no one can take advantage of the supreme friend’s instructions while making his own plans to become happy and entangling himself in the modes of material nature. When there is creation, the living entities take on different forms according to past desires. This means that all the species or forms of life are simultaneously created. Darwin’s theory stating that no human being existed from the beginning but that humans evolved after many, many years is simply a nonsensical theory. From Vedic literature we find that the first creature within the universe is Lord Brahmā. Being the most intelligent personality, Lord Brahmā could take charge of creating all the variety found within this material world.