The third lecture in the current series on global demography has been recorded and uploaded on the GeoCurrents YouTube channel and can be found here.
This lecture covers demographic patterns and processes from the origin of modern humans some 200,000 years ago to the initial development of agriculture around 11,000 years ago. I begin by advising those interested in this topic to watch a YouTube video of Dwarkesh Patel interviewing David Reich, a leading expert on the genetic history of humankind. Reich argues, in essence, that the more we know the less certain we become about the overarching narrative. I then outline the current understanding of the spread of anatomically modern people out of Africa roughly 70,000 years ago and their interactions with the archaic human groups of Eurasia, the Neanderthals and Denisovans. The lecture then goes on to explore such demographically significant issues as the Toba Event 74,000 years ago. The explosion of the massive Toba volcano in Sumatra has been linked to the near extinction of humankind, although recent research indicates that its effects were not nearly so severe. At any rate, rough estimates are given for human populations at various stages of our early history.
The discussion then turns to the expansion of humans to new lands, first to Australia, circa 50,000 years ago, and then to the Americas. I look at the controversies surrounding the original inhabitation of the Americas. I argue that the first people in the Western Hemisphere probably followed the coast and remained somewhat tied to it. A substantial amount of evidence indicates that they were later followed by another wave at the end of the last glacial period years that came from Siberia over the Bering “Land Bridge.” A discussion of the Pleistocene megafauna (mammoths, mastodons, giant ground sloths, etc.) that these newcomers encountered follows. I conclude this section by considering the extinction of most large mammals in North and South America, whether from climate change or human overkill – or some combination of the two.
The lecture then turns to the abrupt climate change that marked the transition from the Pleistocene to the Holocene epochs around 11,700 years. As the globe warmed and the ice caps retreated, vegetational patterns rapidly shifted, forcing people to adapt to new conditions. In the Near East, agriculture began to emerge at this time. I end the lecture by discussing the demographic consequences of the development of agriculture – higher fertility rates and much larger local populations – as well as the health costs that the transition entailed.
