What is the maximum number of persons the world’s land area can support by hunting and gathering alone?
World land area is about 149 million square kilometers, minus 13 million sq. km. for Antarctica, equals 136 million sq. km.
136 000 000 square kilometer
times 100 to convert to hectares
is 13.6 billion hectares of land area.
Estimates of the amount of land area needed per person for hunting/gathering vary, depending on the suitability of the environment for hunting/gathering:
“Based on the preceding calculations, a family of five would require an estimated 200 ha of habitat from which to gather animal and plant food. This estimate is based on an ideal ecosystem, one containing those wild plants and animals that are most suitable for human consumption. Researchers report that, in fact, modern-day hunter-gatherers need much more than 40 ha per person. For instance, Clark and Haswell (1970) estimate that at least 150 ha of favorable habitat per person is needed to secure an adequate food supply. In a moderately favorable habitat, these scientists estimate that 250 ha per person would be required. These estimates are four to six times greater than those in the model presented earlier. In marginal environments, such as the cold northwestern Canadian region, each person needs about 14,000 ha to harvest about 912,500 kcal of food energy per year (Clark and Haswell, 1970).” [David Pimentel and Marcia H. Pimentel, ‘Food, Energy, and Society’, third edition, (Boca Raton, FL: CRC Press, 2008), p. 45-46.]
The land needed ranges from 40 ha/person in an ideal ecosystem, to 150-250 ha/person for a moderately favorable ecosystem. In unfavorable ecosystems, the number can go very high, to over 1,000 ha/person. Let’s assume an overly-optimistic 100 ha/person for hunting and gathering.
So we divide the 13.6 billion ha of land area on 6 continents, not counting Antarctica, by 100 ha/person and we get 136 million persons only. I triple checked the numbers and the math, because it was so low. But that figure is correct. Actually, it is in all probability too high. The value of 100 ha/person for a hunting/gathering food supply is optimistic. Much of the land area would not be sufficiently favorable to obtain that value. Also, the effect of 7 billion persons living on the face of the earth has made large areas of land (cities, suburbs) unfavorable for hunting/gathering. So the real number is perhaps much lower.
If the current world population of 7 billion persons tried to obtain food solely by hunting and gathering, almost everyone would die. In fact, the estimates of the world population are not sufficiently accurate to distinguish between two estimates that are separated by only 136 million persons (plus or minus). So it might be the case that a full 7 billion would die.
We cannot live by hunting and gathering today. How many human persons could the world support in the early centuries of humanity, before the development of agriculture? A relatively small number, realistically only tens of millions of persons worldwide.