Mutual Aid · Chapter
V: Checks to Over-Multiplication explained
This chapter examines the natural checks on population growth, using examples from Hudson's observations in South America.
What happens
This chapter examines the natural checks on population growth, using examples from Hudson's observations in South America. It describes how a sudden increase in mice led to an influx of predators and subsequent collapse due to drought and cold, and how the coypù population exploded after a hunting ban only to be decimated by disease. The chapter argues that overpopulation is rare in nature, with regions like the Amazon and pampas being underpopulated, and that competition for resources is not the primary check on numbers.
Themes in this chapter
Sociability in Nature
The coypù is described as very sociable, communicating with strange tunes, illustrating social behavior in animals.
Resilience of Mutual Aid Institutions
The chapter contrasts the vulnerability of unsocialized species (mice) with the potential resilience of social species, though the focus is on checks to over-multiplication.
Characters to notice
- W. H. Hudson
Provides key observations on the population dynamics of mice and coypù in the Argentine Republic.
- Henry Walter Bates
Cited for his remarks on the scarcity and shyness of animals along the Amazon river.
Key passages
“In the summer of 1872–73, we had plenty of sunshine, with frequent showers, so that the hot months brought no dearth of wild flowers, as in most years.”
During the summer of 1872–73, abundant sunshine and frequent showers led to an unusually rich growth of wildflowers.
Describes the favorable conditions that led to a mouse population explosion.
“scarcely a hard-pressed remnant remains after the great reaction, to continue the species.”
After the population crash, only a small, struggling group of mice survives to carry on the species.
Summarizes the aftermath of the mouse population boom and bust.
“There is, in fact, a great variety of mammals, birds and reptiles, but they are widely scattered and all excessively shy of man.”
Although the region hosts many species of mammals, birds, and reptiles, they are spread out and very wary of humans.
Bates' observation on the sparse distribution of wildlife in the Amazon.