The logical trend would show that about 4-5000BC there was a "beginning" of the present world population.
The logical trend would show that about 4-5000BC there was a "beginning" of the present world population.
“Any documentation of a world population regularly declining?”
Yes, the chart you posted shows such declines in world population. The erason you see such smooth chart lines in the population numbers in the chart for the arly millenia is due to the lack of sufficient detailed data points necesssary to define and delineate such fluctuations. In time periods and regions where there are no surviving written records to assist in identifying and defining documented population numbers, estimates of population based upon settlement patterns, grave frequencies, and other proxies must be usedd to estimate populations with less accuracy than records of polls.
The Fifth Millenium B.C.E. change in rate of human population increase is due to key improvements in himan technologies, particularly in agriculture, anmimal husbandry, and transportation of trade goods. Civilization greatly improved the human ability to adpat to the environment and sustain arger populations which previous technologies were unable to accomplish.
“Notice how they flatten the rate at 4000BC for no apparent reason.”
It is not flattened for no apparent reason. The flattening is only an artifact of the graph using a variable scale on the vertical axis. It’s kind of like how Greenland appears huge on a Mercator projection, because the vertical scale distorts as you approach the boundaries.