Reflection from a riddle. 

Ten humans are hijacked by aliens. The aliens try to decide whether humans are worth preserving. They give the humans a riddle. 

They ask ten persons to line up and put on either black hat or white hat. Each person can see the colors of the hats of those before him. But they cannot see the color of their own hat. 

The aliens give the humans five minutes to design a plan so at least nine out of ten persons can correctly determine the color of their hat. If they do, their lives will be spared. If not, they will be terminated.

Five minutes have passed. Have you figured out the answer? If yes, congratulations! 

Here is the answer. The person at the end of the line can see the colors of the hats of all nine other persons. If the number of white hats is odd, he is supposed to say white (or black, as agreed upon by everyone), otherwise, he would say black. The next person can count the number of white hats of the eight persons before him and deduce what color his own hat is. Each person can determine the color of his hat in this way.

In this riddle, there is no global design. People are not instructed to perform specific tasks beforehand. Rather, each person makes decision based on the action of the previous person. In other words, there is a cascading of actions.

We often wonder how our bodies can build such complex systems based on relative few genes. My guess is that there are a lot of cascading going on inside our bodies. Very often, the immediate environment can generate certain chemical reactions spontaneously without genetic instructions. I don’t know specific examples. Will learn in the future.