The living entities (souls) are impregnated into material nature and based on their past deeds, they take different positions. The activities of the different species of living beings (bodies) are begun from the very moment of creation and the 8.4 million species of living beings are manifested immediately along with the universe. It is not that the activities or the variety of species are evolved. Humans, animals, birds, aquatics, insects, and plants, everything is simultaneously created based on the desires and deeds of the living entities at the last annihilation (last cycle of creation and annihilation). By the will and the inconceivable potency of Lord Krishna, everything is created, maintained, and destroyed. The creation takes place to accommodate the inclinations of the various living entities.
Lord Visnu, an expansion of Lord Krishna creates the first living being in the Universe, Lord Brahma. Who then creates the Manus, Sages, demigods, and women. From a combination of these, the human population of the Universe is increased. The animal and plant species also originate from Lord Brahma. Not all the species are present on planet Earth, and some species are not manifested during certain time periods. This process of creation is repeated in millions of Universes by the inconceivable power of Lord Krishna.