[Stu from NYC]

Originally Posted by ThirdOfFive

Humans have always been prolific breeders. But the things keeping the population in check during times past are definitely NOT the same things keeping it in check today.

The OP has that it took 300,000 years for the population of the globe to reach 1 billion, but only about 200 or so years to go from 1 billion to nearly eight billion. Those numbers are generally accepted as accurate. The seminal event in this growth rate is the Industrial Revolution. Prior to that, natural events (the Black Plague, weather events that were not forecast, other epidemics) as well as some not-so-natural events (The Mongol ravaging of Most of Asia and parts of Europe, for example, killed some tens of millions of people back when the earth had a total population of maybe 360 million) kept the population down.

The industrial revolution and accompanying scientific advances changed all that. better disease control, more enlightened farming techniques, etc. made life on the planet much more secure for the people than previously.

Pew Research has some interesting numbers on that. For example, the rate of births has been falling as better medicine and living conditions have reduced child mortality, with some industrialized nations even experiencing negative population growth. "The global fertility rate is expected to be 1.9 births per woman by 2100, down from 2.5 today. The rate is projected to fall below the replacement fertility rate (2.1 births per woman) by 2070. The replacement fertility rate is the number of births per woman needed to maintain a population’s size." (By Anthony Cilluffo and Neil G. Ruiz, Pew Research Center, 6/17/19). The upshot is that the growth of the human race will level off at about 10.0 billion people and remain more or less constant after that.

I don't think we have too much to worry about.

Thank you, your explanation was much better than mine.