Overpopulation is a condition where an organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...

's numbers exceed the carrying capacity
Carrying capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...

 of its habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

. The term often refers to the relationship between the human population
World population
The world population is the total number of living humans on the planet Earth. As of today, it is estimated to be  billion by the United States Census Bureau...

 and its environment
Environment (biophysical)
The biophysical environment is the combined modeling of the physical environment and the biological life forms within the environment, and includes all variables, parameters as well as conditions and modes inside the Earth's biosphere. The biophysical environment can be divided into two categories:...

, the Earth. Steve Jones
Steve Jones (biologist)
John Stephen Jones is a Welsh geneticist and from 1995 to 1999 and 2008 to June 2010 was Head of the Department of Genetics, Evolution and Environment at University College London. His studies are conducted in the Galton Laboratory. He is also a television presenter and a prize-winning author on...

, head of the biology department at University College London
University College London
University College London is a public research university located in London, United Kingdom and the oldest and largest constituent college of the federal University of London...

, has said, "Humans are 10,000 times more common than we should be, according to the rules of the animal kingdom, and we have agriculture to thank for that. Without farming, the world population would probably have reached half a million by now." The world’s population has significantly increased in the last 50 years, mainly due to medical advancements and substantial increases in agricultural productivity.

The recent rapid increase in human population over the past two centuries has raised concerns that humans are beginning to overpopulate the Earth, and that the planet may not be able to sustain present or larger numbers of inhabitants.