Astrobiology

Abstract

Life on Earth, as realised by plants and animals including man, tends to be often better organised than civilization. The biological engines are so stable and effective that they have managed to survive throughout several Gyr, despite all natural hardships, despite being eaten mutually and/or hierarchically, and despite all natural catastrophes. Even more: until the past century, the diversity of species has grown roughly exponentially with time — interrupted by some ten mass extinctions — thereby conquering all thinkable niches: sweet and salt water including oceanic depths (of ≲ 10 km), land and air, extreme (high and low) temperatures and pressures, corresponding to depths and heights of ≲ 10 km, salt- and sulfur-rich media, darkness and dryness, and even as toxic environments as the interiors of stomachs, or certain locked-off caverns. When they say that life has had more than a Gyr to adjust, they forget that earlier generations had to survive as well, in order to hand over the torch of life: Life must have been well adjusted right from the beginning, down to its most primitive forms. And Darwinian survival of the fittest is a mechanism that may well work at the level of one-celled creatures — which duplicate within 20 min, and exist in huge numbers — but not of lions, elephants, eagles, and dolphins for whose progenitors there are simply not enough generations for random selection; Gold [1999] calls it ‘Darwin’s dilemma’.