Periodic catastrophes over human evolutionary history are necessary to explain the forager population paradox

Proceedings of the National Academy of Sciences of the United States of America • Vol/Iss. 116(26) • PNAS • • Published In • Pages: 12758-12766 •
By Gurven, Michael D., Davison, Raziel J.

Abstract

Researchers looked at four different demographic scenarios (altered mean vital rates (i.e., fertility and mortality), vital rate stochasticity, vital rate covariance, and periodic catastrophes) and their possible effects on the rapid population growth of contemporary human foragers and steady population decline of chimpanzees. They evaluated these variables and the various conditions that would favor a more sustainable zero population growth (ZPG) among 10 small-scale subsistence human populations (Agta, Ache, Hadza, Hiwi, Ju/’hoansi, Gainj, Tsimane, Yanomamo, Northern Territory Aborigines, and Herero) and five wild chimpanzee groups (Gombe, Kanyawara, Mahale, Ngogo, and Taï). The results state that the most effective modifications towards ZPG would include a combination of more than one of the four demographic scenarios tested, with the most realistic solution including both vital rate alteration and an increase in catastrophes.

Samples

Sample Used Coded Data Comment
OtherSources vary per population – see table S1 for population metadata and source citations.

Hypotheses (5)

HypothesisSupported
Through altering mean vital rates (both fertility and mortality) it would be possible to adjust the current rapid growth of contemporary human forager groups to achieve ZPG (zero population growth) p. 12761. Not Supported
Through altering a population’s vital rate stochasticity it would be possible to adjust the current rapid growth of contemporary human forager groups to achieve ZPG (zero population growth) p. 12763.Not Supported
Through altering a population’s vital rate covariance it would be possible to adjust the current rapid growth of contemporary human forager groups to achieve ZPG (zero population growth) p. 12763. Partially supported
Through altering the rate of catastrophes a population experiences, it would be possible to adjust the current rapid growth of contemporary human forager groups to achieve ZPG (zero population growth) p. 12763.Partially supported
Combining more than one of the four demographic scenarios (altered mean vital rates (i.e., fertility and mortality), vital rate stochasticity, vital rate covariance, and periodic catastrophes) increases the likelihood of returning the rate of population growth to ZPG p. 12763.Supported
Documents and Hypotheses Filed By: abbe.mccarter