The principle of population:

-          12000 years ago sedentary agricortures introduce -> population develop

-          Food is essential, it sustains  life, provides energy

-          Thomas Malthus: population changes according to the countries’ resources

-          If the food is too much or too little there is a levelling of population

-          School fish:

- the fish population will costantly grow with a subsistence level

- the fish growth will be exponential if food is too much

- as a result the exeeding population will die and it will be again balanced 

-          Levelling beaten through “preventive checks”