Unfortunately, all life on earth – the only life we know – represents, for all its current variety, the results of a single experiment , for every earthly species evolved from the common ancestry of a single origin. We desperately need a repetition of the experiment (several would be better, but let’s not be greedy!) in order to make a judgement. Mars represents our first real hope for a second experiment – the sine qua non – for any proper answer for the question of questions.
