Delivered by comets.
Abstract: We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction-diversification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is the remarkable evolution of intelligent complexity (Cephalopods) culminating in the emergence of the Octopus. A third focus concerns the micro-organism fossil evidence contained within meteorites as well as the detection in the upper atmosphere of apparent incoming life-bearing particles from space. In our view the totality of the multifactorial data and critical analyses assembled by Fred Hoyle, Chandra Wickramasinghe and their many colleagues since the 1960s leads to a very plausible conclusion – life may have been seeded here on Earth by life-bearing comets as soon as conditions on Earth allowed it to flourish (about or just before 4.1 Billion years ago); and living organisms such as space-resistant and space-hardy bacteria, viruses, more complex eukaryotic cells, fertilised ova and seeds have been continuously delivered ever since to Earth so being one important driver of further terrestrial evolution which has resulted in considerable genetic diversity and which has led to the emergence of mankind. (open access) – Edward J. Steele et al, Cause of Cambrian Explosion – Terrestrial or Cosmic? Progress in Biophysics and Molecular Biology, Volume 136, August 2018, Pages 3-23
Well, if viruses came from outer space, did they get started there? If not, where? How?
See also: Worms survive Siberian permafrost for 42,000 years
Might we find evidence of past life on the Moon? It really depends on how long ago life got started here whether some microbial life could have been trapped on the moon and survived a while. The sagas of the worm that survived the space shuttle blowup and the water bears in space should warn against too-hasty dismissal.
Is that Mars lake way too salty for life? Yes, in Hugh Ross’s expert view. The news copy around life on Mars generally sounds as though it is written for people who have an emotional need to believe that there is life on Mars, whether there is or not. Call it a specialized version of the Drake Equation. The last place to look for reasonable skepticism often turns out to be science writing.
But if we don’t find life on either Mars or Europa… … are we justified in drawing the conclusion that life is just not very common in the galaxy and that we are special? As opposed to They Must Be Out There Somewhere, experienced as an act of faith? What makes that act of faith “science”?
About the universe, the ID guys were right all along? Science fiction writer Vox Day weighs in on thoughtless dismissal of the idea