In the Vedas there is reference to human life during each of the four yugas, yet today we only know a small portion of that history.
The Hayehwatha Institute is interested, through specialized programs to expand human awareness, along with the assistance of evolved souls within the spiritual dimensions of the universe, to explore the universe to understand our human origins. In our initial exploratory research we have found it possible that our existance as a human species extends back further in time than the accepted versions found in science and religion today.
Satya Yuga or Krita Yuga – 1,728,000 years
Treta Yuga – 1,296,000 years
Dvapara Yuga – 864,000 years
Kali Yuga – 432,000 years
There is a lot of information on the internet regarding the Yugas as described in the Vedas. The Wikipedia version is a good place to begin. Two charts present the timelines:

