You're asking for a quick answer for a complex and hard question, as I'm sure you are well aware.
I find that natural selection can be used as an theodicy, if one if willing to reject design arguements (arguments which Thomists reject anyway).
For example, on can cite Dr. Richard Dawkins on the benefits of natural selection in order to justify animal suffering (without that suffering, the goods of natural selection wouldn't arise). And who doesnt enjoy citing Dr. Dawkins as a defence for Theism? ;-)
Overall, although suffering is in itself ontologically evil, it can be, in the context of our fallen world, justified, as in this fallen world, suffering is necessary for great good (suffering is good per accidens). For example, the good of martyrdom cannot exist without suffering, and more importantly, the massive good of God becoming Man would not have happened without the Fall. This all works under St. Augustine's argument that if suffering can point to a greater good, it can be justified. In other words, as long as we realize that perfect goodness cannot arise without suffering ("your salvation was bought with a price"), the AFE doesn't work against Christian theology, unless the proponent of the AFE finds a meaningless evil in which no good can come, which it seems only a omniscient person can ultimately know.
You may wish to meditate on these articles by a Latin Catholic philosopher: