The ability to successfully resist or withstand various environmental traumas or parasitic infection. Pathogens are least resistant to rare alleles. A specific type of asymmetry called fluctuating asymmetry is observed in teeth. It just means that teeth are larger on one side than the other. A biologically strong individual, whether a rat or human can better withstand stress than a weak one.
Fluctuating asymmetry correlates with lower survival and growth rates, and fewer offspring.
In art and architecture is a legendary old proportion known variously as the golden proportion, golden section, or as Fibonnaci Numbers. It is the proportion 1 to .618. The proportion is considered pleasing to the eye and appears in classical architecture and even in Khufu's tomb chamber within the Great Pyramid, Giza, Egypt. The golden proportion applies to the widths of upper incisor teeth and to the lengths of the metacarpals in the fingers. They date from recreational mathematical games devised in the 12 th Century.