We found the seeds.

Reuters carries the story of the first seed of life to be discovered on a comet:

The latest findings add credence to the notion that extraterrestrial objects such as meteorites and comets may have seeded ancient Earth, and other planets, with the raw materials of life that formed elsewhere in the cosmos.

“The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare,” said Carl Pilcher, the director of the NASA Astrobiology Institute in California, which co-funded the research.

That really is how this all could have started.