Pig domestication probably began thousands of years ago. The approximately 150 breeds of European domestic pigs that exist today are primarily descended from the European wild boar and from crosses with the East Asian banded pig, which British seafarers brought to Europe in the 18th century. For centuries, pigs were kept in herds, grazing in the pastures, in the woods, or on the road during the day, and brought to stables at night. Intensive farming did not appear until after the Second World War.
The natural life expectancy of pigs is up to twenty years. Fattening pigs weighing 100 kilograms are usually slaughtered at the age of six months – the age of sexual maturity – and breeding sows as soon as they no longer meet the expected litter performance, usually after a few years.
Pigs have an organized social structure with strict hierarchies and regular daily routines. (Read what a natural pig day would look like here.) Normally, pigs live in herds of 20 to 30 animals, made up of dams and their offspring. The male animals leave the herd after sexual maturity, form separate groups for a certain period of time and finally lead a solitary existence. They only join the gangs during the mating season.