Well this is very old news which just got published in a new paper :
Perfect-waist-to-hip-ratio-is-0.7
I think I saw a video explaining about this long back (atleast a year back). Its basically the “Golden Ratio” says that human (not only human, even animals like gazelle developed such technique in how we see things)
developed a specific way of seeing things around us for survival initially.
For example, to scan a forest environment easier and quicker, it would be easy for a gazelle to follow in a rectangular patern rather than a up/down search.
Hence human got their vision evolved in this manner which is explained by golden ratio. It describes a rectangle with a length roughly one and a half times its width. Many artists and architects have fashioned their works around this proportion. For example, the Parthenon in Athens and Leonardo da Vinci’s painting Mona Lisa are commonly cited examples of the ratio.
When a women has a waist-to- hip ratio of 0.7, “she appears to be most fertile and most likely to produce a healthy offspring” to a man.
This very same logic applies for finding an attractive person too
My-Pedia 