Some historians held the view that the history of mankind was a representative of the wars against starvation, disasters, diseases, etc.
The majority of people had a common but fundamental desire---to survive! It was an instinct, an instinct of each life!
There was a credible survival ability of people: they were omnivorous and high intelligent; they were able to make tools and they knew how to make use the environment and change it... These were the superficial merits of them.
Therefore, someone compared mice’s adaptation to humans’. Others compared cockroaches' toughness to humans’.
No one could foresee that human beings would really have nowhere to hide but to live in a dark, damp place underground, just like the mice and cockroaches.
This story had happened right in this kind of world...