The very recent era of Man may not have produced yet similar forces of nature that were as destructive to life in general, although lesser agents could have time and again decimated mankind and reversed the latter's progress in the building of civilizations.

As early as 0.1_million_B.C. (or 100,000 years ago, reference# wf2), human activities and tools already had effects on the environment discernable to current studies. Men in that long span of time (discounting mass killers) could have had sufficient chance to develop many times over sophisticated societies and civilizations, considering that our current civilization achieved space age status within the  span of 6000_years since it had writing capability around 4,000_B.C.



The human stock itself had even much more ancient roots, diverging from the nearest relative ape in the hominoid family around 7_million_B.C. Analysis by a so called "DNA clock" (a technique in molecular biology - reference# pd1 at the end under 'Printed references') for family members in question was used to pinpoint the divergence.





Credible reference suggest (reference #s pe2, pe3) that humanity had prior civilization capable of wide enough influence on periods earlier than the 4,000_B.C. commonly believed as beginning of current civilization. If not for mass killers, any of those civilizations may still be around, unless of course, it is now well hidden..