Why the 5 thousand years of zero growth?

According to the same book, it’s because not long after people adopted Neolithic technologies, which involved animal herding, farming, and sedentary life, then diseases could spread more widely among the crops, the animals, and the people. Many an early archeological site from this era shows signs of sudden abandonment of a town or village of some thousands of souls. Some of the ruins were burned, some not. Most plagues that kill fast such as typhoid, influenzas, yellow fever, malaria, plague, mumps, measles, and so on don’t leave marks on human skeletons, and are transmitted between humans and our herd animals. In all likelihood, populations would rise and then get wiped out by a plague of some sort affecting themselves, their animals, or their crops.

In other words, it probably was not a time of linear growth of human population (the 180 net new human beings average that I estimated in my last post). But, rather, a period when local human populations would rise and then fall, unpredictably. Apparently, hunter-gatherers limit their births, in part because a mother will carry and nurse a baby until it is a few years old; people who eat a sedentary grain diet are much more fertile. But their surroundings were more shitty (as in, covered with human and animal dung), so, as these settled Neolithic people procreated, lived close together, and had absolutely no defenses against mysterious pests, diseases and such, they also would occasionally die in droves — becasue NOBODY had resistance to any of those diseases.

Any survivors who had heard anything about plagues would learn to leave the town as fast as possible; and if they *ever* returned, would be totally justified in burning to the ground whatever remained.

Apparently it took five thousand years, or about 20 generations, for enough of our susceptible ancestors – the unlucky ones — to be weeded out, and the lucky ones, who just happened to have some genetic feature that provided immunity, to survive and pass along those lucky genes. All of us today are descendants of the lucky ones that survived plague after plague!

After that time, population increased remarkably. Let’s look at those figures

10,000 BC human population about 4 million

5,000 BC human population about 5 million (a rise of about 5 percent per millennium)

0 BC human population about 180 million (a rise of 35 percent per millennium)

2,000 AD human population about 6 Billion – which is about 33 times (not 33 percent, but 33 times) as many people as were present near the birth of Christ. So per milllennium, that is a much faster increase than ever before!