Cambria is one of the names given to Wales. So, for the sake of romance, I'm going to say life on earth began in the Precambrian era, and truly came to bloom during the Cambrian era. And I think there might even be evidence to support my assertion. The Cambrian era is loosely defined as that period of earth that started around five hundred and forty million years ago and came slowly to a conclusion around four hundred and ninety million years ago. Worth noting the Earth itself began to form around four and a half billion years ago, or around nine thousand years ago, depending upon who you talk to.
Since the beginning of the Cambrian era until our very own less pleasantly named Holocene era, there have been a number of cataclysms that have resulted in mass extinctions of life forms. It's estimated that there have been five such events. These mass extinctions have often been referred to as 'winters.' Nor is there any reason to suppose that some time in the near or distant future such a 'winter' might not reoccur. My own view is this, putting bunkers in the ground so that the rich and powerful and their equally annoying offspring might have a place to wait out a 'winter,' or investing in machinery that will zap an approaching asteroid, or entering negotiations with purveyors of a life hereafter, is all of it quite contrary to free market theory.