Survival of the Fittest

In the movie "Onibaba", it shows how women have to survive on their own after their husband, father, etc. go off to war. In the movie, two women basically kill samurai's to steal their armor and than go trade it in for food. The two men, mother in law and daughter in law, basically came up with a plan to lure stranded samurai's in a deep pit so they will die from their fall. Than the two would go down the death hole and strip the samurai's armor, clothing, weapons, and masks and go off to a secret cave and trade in their stolen goods for food. It is sad too see two helpless women forced to kill in order for them to survive. I guess the laws of nature is true that the fittest survive while the weak will die off. In this case these two women chose to survive by killing samurai's and sell off their armors and weapons instead of waiting around until their husband returns.