Douglas Main commenting in Newsweek on study, by Corey Bradshaw and Barry Brook, published in the Proceedings of the National Academy of Sciences and 2 billion people by 2153 if one child per woman on average by 2100 (2014): “The researchers wrote that reducing fertility rates (defined as the number of offspring the average woman has over her lifetime) to 2 from the current rate of 2.37 by 2020 would lead to 777 million fewer "people to feed planet-wide by 2050," for example. But they emphasized that worldwide population would take a long time to stabilize. Several other studies suggest that a world population of between 1 billion and 2 billion "might ensure that all individuals [live] prosperous lives, assuming limited change in per capita consumption and land/materials use." If humans reduced fertility rates to one child per woman on average by 2100, there could be as few as 2 billion people by 2153, they calculated… "The corollary of these findings is that society's efforts towards sustainability would be directed more productively towards reducing our impact as much as possible through technological and social innovation," as opposed to focusing solely on population, said Bradshaw. A primary end goal for these innovations would be to produce energy without greenhouse gases (by embracing renewable energy) and to quit destroying forests and other ecosystems, they added” (Douglas Main, “Even a pandemic wouldn’t create a “sustainable” population, study says”, Newsweek, 28 October 2014: https://www.newsweek.com/even-pandemic-wouldnt-create-sustainable-population-study-says-280338 ).