The evolutionary and ecological benefits of asteroid and comet impacts.

Commonly viewed solely as agents of destruction, asteroid and comet impact events can also have a beneficial influence on processes from the molecular to the evolutionary scale. On the heavily bombarded early Earth, impacts might have delivered and caused the synthesis of prebiotic compounds that eventually led to life. At the organismal and ecosystem level, impact events can provide new habitats through the shock processing of target materials and by enhancing water availability, such as within intracrater lakes. At the evolutionary level, by destroying entire groups of organisms, impacts might have been instrumental in enabling the rise of new groups, such as the dinosaurs and mammals. Here, we synthesize the emerging literature on the beneficial effects of impacts to provide a novel perspective on these extraterrestrial agents of biological change.