Modern science presumes  that the earth came into existence somewhere 6 billion years back. It took another billions of years for the earth to cool down for the origin of living creatures on the  earth.

    Science believes that life originated in water to start with. Then Amphibians(i.e. creatures who could live equally well in water as well as on land) came into existence. As the process of evolution crept on slowly, there was development of peculiar creatures living on land who could swim conveniently in water. After another millions of years somewhere nearly one million years  back, the homo sapiens  (the  human being) as  they stand today, came into existence. Several scientists, century back, have postulated various theories about this evolution. Darwin, Mendel & others postulated various theories on this subject.

    Now we look at  the   ancient belief of 10 incarnation of God-DASHAVATAR

	Matsyavatar	The 1st one which is creature living in water.
	Kacchapavatar	The 2nd one, the amphibians.
	Baravatar	The 3rd one, terrestrial animal who likes to sit and swim in water.
	Narsinghavatar	Ancient Rishies knew that the man did not appear directly after these animals. So they designed a creature in between the the man and animal and named it Narsingh(nar-man, Singh-lion). The 4th one.
	Bavanavatar	The 5th one. That means a small sized human being. They thought that the man appeared in a much smaller form to start with who could stand on his two feet.
	Parasuram Avatar	It was also probable that the man took a very gigantic shape and they called it Parasuram, the 6th incarnation.
	Rama	After that the normal human being of today came into existence(the 7th incarnation)
	Krishna	The 8th one, A normal  human being.
	Gautam Buddha	The 9th incarnation who was born more than 2500years back.
	Kalki	The 10th Avatar is still to come.

    If we look at the sequence of these incarnations, we can understand that the Ancient Indian Rishies had also presumed (centuries ago) the Origin Of Life on the Earth in the same sequence as the science believes today even though they hadn't have advance scientific instruments and tools like today.

    They wanted the human beings to remember and respect their ancestors for ever, so they called them AVATAR(the incarnation of God) and fabricated suitable stories with each one of them which could easily be remembered and passed on to the next generations very easily.