The answer is biological evolution.
The theory of biological evolution explains how organisms evolved during the time. It explains how the characteristics of different species changed over generations. According to the theory, most of current species developed from some distinctly different species that have lived a long time ago.
Fossils are Remains Of Tracers Of Prehistoric Life
There are far to many variables to make a true accurate answer, this is coming from a medical responder BUT lots of texts say about 120 min....but that's very much debatable