Care for the people around us should be extended to care for the animal kingdom and the environment, since all are essentially divine. Hinduism agrees with the theory of evolution which states that we are the continuation of the animal kingdom. Hence reverence for life cannot be restricted to the human kingdom; it must be extended into the animal kingdom. Poor treatment of animals bred for human consumption, or hunting down animals to the point of extinction because of greed and commercialism, go against Hindu teachings.
The Isa Upanishad in its first verse states: View all this that you view as the manifestation of the lord. Seeing the universe as the manifestation of the divine or the spirit is at the heart of Hindu teachings. Desecrating the environment is viewed as compromising the dignity of the spirit that underpins everything.
Contextual limitations on the principle of reverence for all living things and the environment: Hindus believe there is a hierarchy in creation, as some things are considered more sacred than others. Human life is seen as more valuable than animal or plant life. Divinity has become most clearly manifest in human form through the evolutionary process. This is why it is considered legitimate for humans to live off other living things or to take medicine to destroy bacteria and viruses that may be detrimental to their well-being. Sometimes this ‘violence’ is unavoidable.
It is also valid to defend and protect yourself from other human beings who may want to harm you. In the story of the Mahabharata, Krishna urged Arjuna to fight the wrongdoers as it was his duty to protect the righteous. Hindus have never gone out of India to conquer other people or impose their authority on others as that goes against the grain of Hindu teachings.