My book is out! https://www.amazon.co.uk/Wyclifs-Dust-Western-cultures-printing/dp/B0B5PPXSQH/
I’m a social scientist in an economics department in Britain. Two of my interests are experimental economics and the social causes of genetic variation. I have a newsletter at https://wyclif.substack.com.
I don’t know about population sizes either. Maddison (cited at https://en.wikipedia.org/wiki/Estimates_of_historical_world_population#By_world_region) says that in 1500, Americans were only about 4% of global population, with 20% being in Europe and 68% in Asia.