An ecological theory of changing human population dynamics

Abstract

The dependence of humans on nature has come into focus as the human population continues to grow, resources diminish and production technology stagnates – threatening human well‐being on a global scale. Numerous previous models describe human population dynamics, in relation to a multitude of different factors. However, there are no consistent driving factors of human demography through history, which makes predicting future changes more challenging. Here, we review the literature on human population growth from empirical data and previous models, which allows us to highlight key trends in demography and land cover changes. We then establish an ecologically driven theory of demographic change that uses resource accessibility as a proxy for socio‐economic factors. The theory combines multiple concepts to represent 12 millennia of past population dynamics through simple human–nature relationships. Furthermore, the model allows us to compare different scenarios related to technological progress and land cover change, for which we find that the peak human population is highly dependent on whether technological developments continue at an exponential growth rate, or if and when there is a saturation point. Likewise, agriculture is shown to be helpful for growing the population, but nature is ultimately needed to maintain the human population. A plain language summary is available for this article.

Unequal access to resources undermines global sustainability

“…This is supported by empirical data showing that there are two groups of individuals with distinct demography, development structures, and consumption patterns (Oswald et al, 2020), in addition to an analysis of The World Bank (2019a) data given in the appendix. We use this idea of distinct economies with distinct practices and apply it to an ODE model of global land management and population growth (Henderson and Loreau, 2019). We modified the Henderson and Loreau model to incorporate two regions, movement of people and goods and inequality.…”

The Evolution of Agricultural Drainage from the Earliest Times to the Present

“…Considering the exponential population growth on the planet [144], the request for greater food and consequently the need for an agricultural drainage evolution should be considered [145].…”

Agricultural land use and the sustainability of social-ecological systems

“…Agricultural land is exhausted and degraded, at different rates depending on the surrounding landscape, and ultimately becomes unproductive (Henderson and Loreau, 2019; Cramer et al, 2008). Natural land contributes to the recovery of surrounding land, acting, for example, as a species pool necessary for recolonization by native species (Cramer et al, 2008; Baeten et al, 2010).…”

“…One study suggested that social inequalities and environmental degradation were present in all known past societal collapses (Motesharrei et al, 2014) and as such the authors proposed a general model showing various projections of socio-ecological collapses as a result of the feedbacks between social inequality and resource exploitation. More recently, Henderson and Loreau (2018) and Henderson and Loreau (2019) proposed a general theoretical framework to explain human demography across history in relation to resource accessibility, which can be used to explain the population explosion in the last century and potential future scenarios. Through an economic-ecological model Lafuite and Loreau (2017), Lafuite et al (2017) and Lafuite et al (2018) investigated how time lags in the response of biodiversity to anthropic perturbations can feedback on the human population via shortages in food production and undermine the sustainability of the socio-ecological system.…”