I am in the middle of reading
1493 by Charles Mann, author of
1491 (which I haven't read yet) and he does discuss possible incentives to slavery which have been touched upon in this thread (before the derail anyway

). Mann starts by laying out the case that British colonies would have been the least likely places for slavery to take root:
- Indentured servants were much more productive than slaves as they knew the language, customs and work requirements. They were also willing participants and moreover proper subjects who would have moved on to become productive landowners when their contracts expired.
- British culture was the most anti-slavery in Europe. I am very unsure of this claim given English conduct in Ireland and English participation, including direct investments by Her Majesty Queen Elizabeth, in John Hawkins' slaving voyages during the 1560s. Social mobility was higher in England than most of Europe and making a fortune through owning or especially trading slaves was a fast way to move on up in society (this also contributed to the Englishman's gleeful pursuit of piracy). On the other side of the coin (not mentioned in this book, at least not yet) the Cimmarrones - escaped African slaves - were recognized by England and even earlier by Spain to be a serious threat to the security of Spanish colonies, one which the Spanish themselves created.
Mann then lays out his argument with two small and one very large reasons why slavery took root south of Chesapeake bay, As he put it, colonies north of the Mason-Dixon line were societies that owned slaves - colonies south of that line developed into slave-owning societies.
- Labor was desperately short and land unbelievably plentiful to the point that those indentured servants that fit right in would sometimes run off to another colony to gain a fresh start as a freeholder, thus reducing their value a bit. Though this would have happened in all the colonies, I suppose it likely would have been more desirable to run from the sweltering south to the more salubrious north. Moreover, the total supply of indentured servants dried up periodically during the English Civil War and English-Dutch wars.
- Indian tribes bordering on Carolina colony were almost endemically at war, a continuation of the shakeout from the collapse of the mound-building societies a couple of centuries before. (Not mentioned in the book was that northern tribes, especially the Iroquois Confederation, had a more developed diplomatic toolbox for conflict resolution.) A byproduct of this constant war was capturing and owning slaves, which was greatly exacerbated by colonists' demand for labor, willingness to trade guns, and demands that their new partners repeatedly hit tribes allied with the Spanish (who were trying to push the English out of Carolina). So the southern colonies developed a large slave market even before Africans started arriving in large numbers.
- Finally, and most importantly, were the microscopic immigrants: Malaria (plasmodium vivax, endemic to much of the Old World, including Southeast England; and plasmodium falciparum, endemic only to the tropics and subtropics, including Southern Europe) and Yellow Fever.
As can be guessed by the name, mal-aria (bad air) was not well understood at the time, often called tertiary fever, and was pretty widespread. The original Jamestown colonists probably brought p.vivax with them, but the disease did not stand out much, any deaths not of starvation or indian attacks (lots of those too) were called "seasoning deaths", usually caused by p.vivax or another disease jumping a weakened malaria victim. Mann points out that after a steep and costly learning curve seasoning deaths had been reduced to a mere 10% of new arrivals when they began to spike upwards again, almost certainly marking the arrival of p.falciparum.
Now during this time population records showed slavery did develop in, but did not take over, the Old South. That came after the "Yellow Jack" hit in the 17th century. Of the victims with white or red skin, fully half of the adults died vomiting blood (children were much less likely to die of Yellow fever, though more likely to die from Malaria just to make things fair). That is when the scales tipped in favor of African labor, despite the much greater cost and risk (both physical and spiritual) associated with chattel slavery. West and Central Africans were largely immune from Malaria, and new arrivals often had Yellow Fever as a childhood ailment. Their survivability in spite of their harsh treatment made them the only sure source of labor for the South, so the machinery (both physical and spiritual) for large scale bondage were slowly built over the late 17th to the early 19th century.
As an aside Mann also makes a case why large plantations flourished in this region rather than small family farms. A large farm with twenty workers could weather the loss of a hand during harvest time better than a small farm with three. Large plantations had the space for a house on a huge manicured lawn atop a treeless, breezy hilltop - the better to keep away the mosquitoes. And finally wealthy farmers could afford to literally head for the hills (or for the coast) during the sickly season in the fall. It's definitely easier to maintain a farm if the farmer ain't dead.
Good book so far, the author throws a few squirrelly theories on the table but nothing on the level of China discovering America. I am just beginning the chapters on Asia but I believe Mann attempts to answer the "why Europe and not China?" question that Jared Diamond refused to answer in
Guns, Germs, and Steel.