New estimations of habitable land area and human population size at the Last Glacial Maximum

The estimation of human population size during the Pleistocene is complex, and one which has been dealt with extensively in the literature. However, because many of these previous estimations are based in part on archaeological site distributions, they are more a reflection of present-day geography than of what the Earth looked like in the past. We address this issue by calculating an estimation of habitable land area during the Last Glacial Maximum (between 22 and 19 kya) when sea level was 120 m lower than today using the polygon creation function in Google Earth. We then subtract areas of land that were likely uninhabitable during the LGM - either due to glacier cover, extreme aridity, elevation, or areas at high latitudes. From this, the combined habitable land areas of Eurasia, Africa and the Australian landmass are estimated as 76,959,712.4 km2. This estimation is then coupled with population density data for medium-to large-bodied carnivores, and ethnographic population density data for hunter-gatherers culled from the literature. Total human census population size in the Old World during the Last Glacial Maximum is estimated at 2,117,000-2,955,000 based on carnivore densities and 3,046,000-8,307,000 for hunter-gatherer densities.