Ideas and methods of statistical and nonlinear physics have been shown to be useful for understanding some interesting problems in physical systems. After the development of modern biology, it is of interest to know whether one can use ideas and methods of statistical and nonlinear physics to understand some interesting biological problems. In this talk, I will show that some simple models from statistical and nonlinear physics can be useful for understanding some interesting biological problems, including：

 (1) why ancient seeds nonseeds can maintain in viable non-equilibrium state for very long time ?

 (2) under what conditions will proteins aggregate and cause neurodegenerative diseases?

 (3) what are the mechanism of biological polymorphism and speciation ?