Malthusian growth model

The Malthusian growth model, sometimes called the simple exponential growth model, is essentially exponential growth based on a constant rate of compound interest. The model is named after the Reverend Thomas Malthus, who authored An Essay on the Principle of Population, one of the earliest and most influential books on population.



P(t) = P0ert

where P0 = Initial Population, r = growth rate, sometimes also called Malthusian Parameter, t = time.

Exponential law

As noted by Peter Turchin (Does population ecology have general laws?, 2001 and Complex Population Dynamics, 2003), this model is often referred to as The Exponential Law and is widely regarded in the field of population ecology as the first principle of population dynamics,[citation needed] with Malthus as the founder.

At best, it can be described as an approximate physical law as it is generally acknowledged that nothing can grow at a constant rate indefinitely (Cassell's Laws Of Nature, James Trefil, 2002 - Refer 'exponential growth law'). Joel E. Cohen has stated that the simplicity of the model makes it useful for very short-term predictions and of not much use for predictions beyond 10 or 20 years (How Many People Can The Earth Support, 1995). Antony Flew - in his introduction to the Penguin Books publication of Malthus' essay (1st edition) - argued a "certain limited resemblance" between Malthus' law of population to laws of Newtonian mechanics.

Malthusian law

The exponential law is also sometimes referred to as The Malthusian Law (refer "Laws Of Population Ecology" by Dr. Paul Haemig, 2005).

Rule of 70

The rule of 70 is a useful rule of thumb that roughly explains the time periods involved in exponential growth at a constant rate. For example, if growth is measured annually then a 1% growth rate results in a doubling every 70 years. At 2% doubling occurs every 35 years.

The number 70 comes from the observation that the natural log of 2 is approximately 0.7, by multiplying this by 100 we obtain 70. To find the doubling time we divide the natural log of 2 by the growth rate. To find the time it takes to increase by a factor of 3 we would use the natural log of 3, approximately 1.1.

Logistic growth model

The Malthusian growth model is the direct ancestor of the logistic function. Pierre Francois Verhulst first published his logistic growth function in 1838 after he had read Malthus' An Essay on the Principle of Population. Benjamin Gompertz also published work developing the Malthusian growth model further.

See also

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Malthusian theory — refers to: *Malthusian catastrophe *Neo malthusianism *Malthusian *Thomas Malthus *Malthusian growth model *Overpopulation *An Essay on the Principle of PopulationRelated: *The Population Bomb *Subsistence theory of wages *Club of Rome *Risks to… …   Wikipedia

  • Malthusian catastrophe — A Malthusian catastrophe (also phrased Malthusian check, Malthusian crisis, Malthusian disaster, Malthusian fallacy, Malthusian nightmare, or Malthusian theory of population) was originally foreseen to be a forced return to subsistence level… …   Wikipedia

  • Malthusian equilibrium — A population is in Malthusian equilibrium when all of its production is used only for subsistence. Malthusian equilibrium is a locally stable and a dynamic equilibrium. See also Thomas Malthus See this article for further exposition. An Essay on… …   Wikipedia

  • Exponential growth — The graph illustrates how exponential growth (green) surpasses both linear (red) and cubic (blue) growth.   Exponential growth …   Wikipedia

  • Population growth — is the change in population over time, and can be quantified as the change in the number of individuals in a population using per unit time for measurement. The term population growth can technically refer to any species, but almost always refers …   Wikipedia

  • Irruptive growth — Irruptive growth, sometimes called Malthusian growth, is a growth pattern defined by population explosions and subsequent sharp population crashes, or diebacks. It is an extension of the Malthusian growth model and can occur when populations… …   Wikipedia

  • Mathematical model — Not to be confused with the same term that is used in model theory, a branch of mathematical logic. An artifact that is used to illustrate a mathematical idea may also be called a mathematical model, the usage of which is the reverse of the sense …   Wikipedia

  • Economic growth — GDP real growth rates, 1990–1998 and 1990–2006, in selected countries …   Wikipedia

  • Classical theory of growth and stagnation — Classical economics refers to work done by a group of economists in the eighteenth and nineteenth centuries. The theories developed mainly focused on the way market economies functioned. Classical Economics study mainly concentrates on the… …   Wikipedia

  • Unified growth theory — In economics, endogenous growth theory or new growth theory was developed in the 1980s as a response to criticism of the neo classical growth model. In the exogenous neoclassical growth model the long run rate of growth is determined by… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.