Population (human biology)

A human population is the set of people living in a particular geographic area, increasing or decreasing in size over time, but in human biology, a human population may be defined more precisely as "a group of individuals who are more likely to mate among themselves than among others", which is influenced by a number of social and cultural factors. Thus, a larger geographic population can be considered as made of smaller breeding populations that coexist together, but in practice, a population is usually defined by a geographic area, which can be based on a settlement, or larger territories (a country, region, city, or the whole world).

Population genetics studies differences between populations and differences inside a population. 99.9% of the human genome remains the same across all human populations, but the other genes can be different. Populations tend to have different phenotypic traits based on their geographical location and so may carry varying gene pools, but physical traits are not often used to define a population. Aside from the term "population", humans can also be grouped as races and ethnic groups.

Demography is the statistical study of human populations. Additional criteria may be used to define a demographic population or subpopulation, such as sex and age, as in the female population over 60 years of age. Demographic statistics may involve the structure (like age and sex distribution), spatial distribution, and size of a population, or involve population dynamics (the change of the size and age of a population). However, demographers use the term "population" differently from biologists, even if there are some similarities between these definitions: biologists study the number of individuals in a particular area and its evolution over time under varying conditions, while demographers count individuals by some certain criteria at a given time in a specific region.