Where did today's spiral galaxies come from?

Using data from the NASA/ESA Hubble Space Telescope, astronomers have created a demographic census of galaxy types and shapes from a time before the Earth and the sun existed, to the present day. The results show that more than half of the present-day spiral galaxies had peculiar shapes only six billion years ago, which, if confirmed, highlights the importance of collisions and mergers in the recent past of many galaxies. It also provides clues for the unique status of our own galaxy.[....]