Time, life and the Earth

Modem developments in the Earth sciences have revealed, for the first time, how our planet actually 'works.' For biologists. they have brought a fresh understanding of the interwoven histories of the physical and the living worlds. In turn, new biological discoveries show how early in Earth's history fife arose and how it was able to flourish even under the apparently hostile conditions of the young solar system. In particular the high ocean temperatures following meteor impacts would not have precluded the successful progress of so-called hyperthermophilic prokaryotic organisms. The early problems which evolutionary biologists faced, when presented with estimates of the age of the Earth as a few tens of millions of years, have now been replaced by arguments concerning mechanisms underlying the variable rates and patterns of evolution. Life and the Earth have reciprocally interacted over billions of years and repeatedly planetary processes have led to mass extinctions whose dramatic results can be seen in the fossil record even though the details of such events remain problematical. So far mass extinctions have resulted in increased opportunities for the survivors; the current human-induced extinction is unlikely to do so.