Earth and its solar system started to form around five billion years ago. Life came into existence soon after, first in the form of plants. The earliest living creature on Earth was a single-celled organism. Then more complex aquatic and land animals appeared. The Indian subcontinent was formed from glaciers about forty million years ago. Where there are now the mighty Himalayas, there once were oceans—there is evidence of fish fossils on the rocks of the Himalayas.
Man descended from apes around six million years ago (proto-human-orrorin tugenensis species). This is the time he started to walk on his two hind limbs; that is, he became a biped. The first appearance of man was in the Sahara region of the African continent. From there, man moved to the east, west, north, and south. Modern human (Homo sapiens-thinking man) originated about 200,000 years ago, reaching full maturity around 50,000 years ago.
Man is superior to other beings because of his highly developed brain. This organ has billions of specialized neurons and neurological pathways with which we think and can use our free will. Before this development, beings functioned only through instinct. The main feature that differentiates the modern brain from that of our early ancestors is its capacity to restrain the instinctive behavior—the activity of the lower brain—by its voluminous gray matter, which is much less developed in lower animals. The modern human brain has over hundred billion nerve cells, called neurons, mainly in the grey matter cortex. It is believed that only 10 to 20 percent of these are ever used. This in itself offers a great potential for further human development.
Even as the theory of evolution is wholly endorsed by science- right from single-celled organisms to the proto-human-orrorin tugenensis species that finally came to be known as “man”, from the lowest to the highest forms of life, Hindu Rishis went one step further and recognized this concept in a spiritual way by understanding lower animals as the virtual ancestors of human beings and propounding the awareness of cosmic unity at the highest level. Hindu theology believes in the celestial unity of all beings.