Almost ten thousands years ago our specie went through a radical nutritional  change. We evolved from "hunters and gatherers" into an "agricultural" society.  In our specie's  history this is a real drastic  revolution.

 Suddenly we started producing our own nutritional needs instead of  running and walking looking to satisfy our constant daily  hunger.
Before long  we developed ways to preserve and store crops. This allowed   the  formation of  agricultural settlements and the potential demographic increase.
The direct consequences of that shift are many to list but for the purpose of our topic;
 -the wheat cultivation took place around major rivers; Nile in Egypt,  Tigris Euphrates in Mesopotamia and rice in China, that is how organized societies and  civilizations were born.
- this  new and sudden change created a major dilemma for our mankind.

Our digestive system  cannot adapt that fast. Ten thousands years is a blink of an eye.  It took millions of years to produce our organism with its intricate  enzymes, hormones,  proteins, digestion, metabolism, and so on. All  of these systems  are extremely complex and very slow to adapt to a new environment.

In time, the staple of our food consumption was based on carbohydrates, wheat  derivative in most of the world and rice in Asia.

 Two elements became associated with survival, bread and salt.
Bread for caloric source and salt for survival when traveling in hot climate; on foot or on the back of animals ( camels and horses).

Romans legions walked  across long distances carrying with them those two items as there pay. The word salt became the origin of salary.

The bread was not easy to produce. It took generations  to master the art of making bread.
 Milling the wheat kernels into flowers required the invention of  "millstones", and that took a long time to master.
The idea of then mix it with water to create a " dough" and then another invention; baking it.
In time the bread and salt acquired  cultural and spiritual dimension;
sharing them with a stranger became  a of way of connecting with our follows human beings.
Yet from a nutritional point of view, food became plentiful. Our body is used to go for long stretch without food. Our genes are very thrifty. For millennia famine was  around the corner. To survive ,our genes  had to save every ounce  of extra calories as fat. That led to our current struggle with weight.  More to come....