When the first Spanish explorers arrived in the new world they found the indigenous people of the Caribbean preserving meats in the sun. This is an age old and almost completely universal method. The chief problem with doing this is that the meats spoil and become infested with bugs. To drive the bugs away the natives would built small, smoky fires and place the meat on racks over the fires. The smoke would keep the insects at bay and help in the preserving of the meat.
Tradition tells us that this is the origin of Barbecue, both in process and in name. The natives of the West Indies had a word for this process, “barbacoa”. It is generally believed that this is the origin of our modern word Barbecue, though there is some debate on the matter.
The process began to evolve with the migration of Europeans and Africans to the region of the Southern United States. European pigs and cattle were transplanted to the new world and became the primary meat source for the colonies, pork being the meat of choice in the South due to the ability of pigs to thrive with little care. The racks used to dry the meat were replaced with pits and smoke houses.
Now pit cooking is by no means new at this point in history or specific to any particular region of the world. If we define Barbecue as a process of cooking meat (or specifically pork) in pits then the inventors of this process are probably the Polynesians who have been masters of slow, pit cooked pork for thousands of years. So we will have to leave the definition for another time.
The process of slow cooking meat in early colonial times was often reserved for poor cuts of meat left for slaves and low income peoples. Higher quality meats had no need for a process of cooking that would reduce the toughness of the meat. Throughout the south Barbecue has long been an inexpensive food source, though labor intensive. But I am getting ahead of myself.
One thing to remember that without a process of refrigeration, meat had to be either cooked and eaten quickly after slaughter or preserved by either a spicing or smoking process. Traditionally spicing requires that large amounts of salt be used to dry the meat and lower the ability of contaminants to spoil the meat. Smoking in this period of time had much the same effect. The indigenous practitioners of Barbecue, cold smoked meat meaning that the meat was dried by exposure to the sun and preserved by the addition of smoke.