Critics of exogenesis note that the proper conditions to maintain life are rare in the universe, and would not likely survive the trip inside Earth's atmosphere. But new data on comets offers evidence that our ancestors were, indeed, extraterrestrial.
In a paper published in the International Journal of Astrobiology, Chandra Wickramasinghe of the Cardiff Centre for Astrobiology — one of the earliest proponents of the theory of panspermia, that the seeds of life exist throughout the universe — revealed his team's calculation, which indicate that large reserves of water likely existed inside comets in our solar system, that happened to form around the same time as the Earth:
The Cardiff team has calculated the thermal history of comets after they formed from interstellar and interplanetary dust approximately 4.5 billion years ago. The formation of the solar system itself is thought to have been triggered by shock waves that emanated from the explosion of a nearby supernova. The supernova injected radioactive material such as Aluminium-26 into the primordial solar system and some became incorporated in the comets. Professor Chandra Wickramasinghe together with Drs Janaki Wickramasinghe and Max Wallis claim that the heat emitted from radioactivity warms initially frozen material of comets to produce subsurface oceans that persist in a liquid condition for a million years.
Wickramasinghe claims that a "large fraction" of the 100 billion comets in our solar system probably contained liquid interiors, with ideal conditions for the growth of bacteria, which perhaps lends greater credence to Wickramsinghe's theories on the extraterrestrial origins of life.