Isolated disks couldn't support such huge bends in themselves. Left to itself the warp shape would simply wind up very soon and we would be left with a very thick disk. These warps are evidence that the disks are in the grip of a powerful vice that is bending it out of shape as well as keeping it thin. Again the finger prints of dark matter. All the chemistry, barring some initial chemistry in the early Universe, happens inside stars.
Stars are responsible for cosmic cooking today.
And here-in lies the fundamental importance of understanding the chemical evolution of galaxies. Because of the intimate connection of stars and chemical evolution, information on the chemical evolution tells us about the stars, both of today and of the distant past. The information is encapsulated into two functions. These two functions together describe the star formation in a galaxy at any time. Since this is intimately connected to chemical evolution of a galaxy understanding it will tell us about the history of star formation of that galaxy.