An understanding of the size and density of the population is crucial to researchers from various disciplines, such as demographers, economists, historians and social scientists. For contemporary research accurate figures on population characteristics are available, and for most parts of the world on a regionally detailed level. However, for more historic time periods, say pre 1950, such numbers are readily available for only a small part of the world. Information on population characteristics of the past helps us to explain economic and social phenomena of today, such as: economic growth, migration, life expectancy and segregation, as well as to make better projections of population growth in the (near) future.
The lack of historical data on populations has been recognized by Colin McEvedy and Richard Jones who in 1975 provided estimates for the world population by country in their "Atlas of World Population History". Ever since this inspiring and unprecedented work researchers have tried to collect additional information on populations in the world. Some of this work aims at finding more regionally detailed data, harmonizing geographical and temporal variant data and extending information on various characteristics of populations, such as age distribution, gender ratio, and population density. This website acts as a hub for these researchers and provides a portal for their research output.
World population in 1860
Source: https://www.clio-infra.eu/Indicators/TotalPopulation.html