Scientific American did this whole series of posts on optical illusions (it’s old, but I just found it), and one section was entirely on how we perceive faces. Amazing stuff. My favorite part of the faces post was how we determine if a face is male or female. Look at these two faces and tell me- which one is male and which one is female?
The only difference is that the contrast was turned up on the left face. I like to look at people’s faces a lot and see if I can figure out what makes them beautiful, and I noticed a while ago that often it was the presence of defined eyebrows and eyelashes. That’s it. Start looking around at the women you find to be hot in your own town. Interesting stuff. The post has a lot of other fun with faces, go check it out!