f1a32aee_Evolutionary_physiology__Event
[Date] 3900 Ma [Event] 
Late Heavy Bombardment: peak rate of impact events upon the inner planets by meteoroids. This constantdisturbance may have obliterated any life that had evolved to that point, or possibly not, as some earlymicrobes could have survived in hydrothermal vents below the Earth's surface;or life might have beentransported to Earth by a meteoroid.
Evolutionary physiology
Event