If you take yourself as primarily physical, then beauty too for you would be something just physical. You will look at the woman most capable of successfully reproducing. That’s the prakritik definition of beauty.
The first thing that comes to mind is flowers. What are flowers? Flowers are the reproductive organs of the plant or the tree, aren’t they? Now you know why you are attracted to particular physical parts of a woman: Those parts are most likely to be the ones that are related to her capacity to reproduce. Most women would feel attracted to a male who has a certain build and, therefore, can offer protection to the offspring.