The Indians also believed that any animal could be reproduced and evolved only from pre-existing animal. This belief also formed the hypothesis for the organic evolution theory. According to Brihaddraoyaka Upanishad, Virdjan got bored of loneliness and hence adopted binary division like an ameba and became two individuals. In this, one of them acted like the male while the other as a female.
Subsequently, these individuals assumed different animal forms such as ants, cattle, donkey, goats and pigs. Thus, the whole world was populated by evolving one group of animals into another. However their classification of animal world was on the basis alone. This was because they did not believe of external forms in killing and dissecting the animals for their study.
Ancient Indian people were aware of the role played by heredity and environment in the development of an individual. In Yajurveda, there is a prayer which reads, "Give us cows that have abundance of milk, bulls that have full vigor and vitality, horses that can face challenges of any enemy, a ruler who is courageous and fearless, intellectual son and a wife who can take good care of the young and old."
There are innumerable instances in our scriptures where ancient Indians had mastered animal languages. While king Kekaya was with his queen, he overheard the conversation of a pair of birds nesting in his courtyard which made him laugh.
He admitted to the queen that he understood birds' talk. But he refused to share this with others which were forbidden. When the queen insisted to know the contents of the bird's conversation, the king preferred to divorce her on the advice of his guru. It was the same guru who had blessed this boon on the king than divulge the code.
Two thousand year old Panchatantra also contained numerous stories of animals. In these stories, the animals have been given prominence. This collection of stories was also the basis for 'Aesop's Fables.' The Aesop's fables are popular not only among the children but also with the adults.
The court poets have written numerous collections in which the animal life has been described in minute details. For example, Kalidasa and Bana gave a vivid picture of a variety of animals that lived together at ashrams.
Apart from this, the emperors, kings and queens also adopted different animals as their emblems like for instance; the Gangas of Talkadu opted for an elephant, whereas a lion was Kadamba's choice. Hoysala's emblem has a tiger whereas the Vijayanagara kings settled for a boar.
Mysore Maharajas went for Ganda-bherunda, which was a two-headed mythical bird. These emblems were printed on flags. These flags were hoisted at the time of different religious functions. Coins of different denominations were minted by embossing these emblems. These emblems were also displayed prominently on temples, forts and palaces.
The crocodile is given prime of place in Hindu religion and culture. It is believed that the Ganga River depended on a crocodile for her very frequent visits to the Bay of Bengal from the Himalayan Mountains. The rain-god Varuna also rode on Makara. Kamadeva's emblem was Makara. Hence his wife carried it whenever she went.
At times the couple also took a joy ride on this animal. In one of the expeditions of Himalayas, Hanuman was bathing in lake when all, of a sudden a huge crocodile clasps his legs. With great difficulty he dragged the animal out of water. The cruel animal then turned into a beautiful damsel and proclaimed that because of Daksha's curse she became a crocodile. However, Hanuman's contact revoked the curse. Similarly, when Hanuman was returning from Lanka his perspiration fell in the mouth of a Nakshtra and she gave birth to Makara Dhwaja.
Apart from all this, deer was also associated with innumerable stories. Maricha assumed the form of a golden deer in order to attract Sitadevi. Lord Shiva got wrapped up in deer skin. Vayus chariot was pulled by a pair of deer. Musk-deer, Kasturimriga, was the nearest relative of deer. Vashistha gets Kamadhenu for supervising Samudra Manthana operation.
Thus the level of importance attached to animals by the ancient Indian people was so great that they regarded animals as representatives of God sent on the earth. They also learnt their language in order to communicate with them which are quite different to the treatment which the animals receive today.