In This Article Expand or collapse the "in this article" section Gene Flow

  • Introduction
  • General Overviews
  • Early History
  • The Modern Synthesis

Anthropology Gene Flow
Blaine Maley
  • LAST REVIEWED: 03 May 2021
  • LAST MODIFIED: 28 July 2015
  • DOI: 10.1093/obo/9780199766567-0057


Gene flow is a term that describes mechanisms of gene transfer from one population to another. In anthropology, gene flow more generally refers to allelic change due to movement of individuals from one place to another. Referencing the specific context of transferring genetic variation between populations, gene flow is often used interchangeably with migration, although migration also includes population movement into unoccupied regions, which according to some sources is not considered gene flow. Gene flow is one of the primary mechanisms of evolution, generally modeled along with genetic drift, mutation, and natural selection. A multifaceted evolutionary force, gene flow is often considered to work in opposition to the other evolutionary forces (although this is context dependent), maintaining genetic and phenotypic homogeneity across subpopulations within taxa. As genetic drift functions to push alleles toward fixation, especially in small populations, gene flow works to prevent fixation and to maintain heterozygosity (the presence of multiple alleles at a loci in the defined population). In this way it is the balance of gene flow and genetic drift that dictates a population’s ability to maintain genetic variation. The importance of gene flow as an evolutionary force becomes powerful when it is limited, and limiting of gene flow between taxa or demes is accomplished through the construction of barriers to mating or through isolation mechanisms (generally constrained to geographic and reproductive barriers). Mechanistically, gene flow can be quantified to model heterozygosity changes in populations due to the number of migrants, variability of migrants—how deviant are their gene pools relative to the assuming population (usually a function of distance or time), and the impact of the other evolutionary forces. A number of population genetic models have been developed to model the role of gene flow in managing population structure between populations and across geography. These models help anthropologists and biologists understand and quantify migration in human and primate populations, including the processes by which these populations expand, interbreed, and evolve.

General Overviews

Every introductory textbook in biology and evolution discusses gene flow as an evolutionary force; see Zimmer and Emlen 2013 for a good example. Most of the work in anthropology that examines gene flow is on the genetic origin and history of modern humans, which has resulted in the current geographical spread of human variation across the globe. Several good textbooks on human variation are available, including Relethford 2005; Molnar 2005; and Mielke, et al. 2011. In addition, several general-audience-oriented books that discuss the history and spread of modern humans are accessible, including Cavalli-Sforza 2000 and Olson 2002. Cabana and Clark 2011 provides a useful general overview of the question of migration in human anthropology studies, by using a multiple-subfield approach. The topic of gene flow is strongly interrelated with more-general discussions of evolutionary theory; however, several review articles, including Wijsman and Cavalli-Sforza 1984, Slatkin 1985, and Slatkin 1987, address in detail the importance of gene flow in evolutionary theory and population genetic studies.

  • Cabana, G. S., and J. J. Clark, eds. 2011. Rethinking anthropological perspectives on migration. Gainesville: Univ. Press of Florida.

    DOI: 10.5744/florida/9780813036076.001.0001

    An overview of the study of human migration that incorporates the latest cultural, archaeological, genetic, and linguistic methods. These methods are demonstrated in a number of case studies.

  • Cavalli-Sforza, L. L. 2000. Genes, peoples, and languages. Translated by Mark Seielstad. New York: North Point.

    Popular monograph explaining human variation from the perspective of genetic variation, human history, geography, and language.

  • Mielke, J. H., L. W. Konigsberg, and J. Relethford. 2011. Human biological variation. 2d ed. New York: Oxford Univ. Press.

    More advanced text on human variation that delves into genetics and mathematical models of evolutionary theory.

  • Molnar, S. 2005. Human variation: Races, types, and ethnic groups. 6th ed. Upper Saddle River, NJ: Pearson Prentice Hall.

    A classic textbook on human variation that incorporates the importance of gene flow, migration, and isolating mechanisms to explain the current distribution of human variation.

  • Olson, S. 2002. Mapping human history: Discovering the past through our genes. Boston: Houghton Mifflin.

    Popular monograph explaining human evolution on the basis of genetic variation.

  • Relethford, J. H. 2005. The human species: An introduction to biological anthropology. 6th ed. Boston: McGraw-Hill.

    An introductory textbook to biological anthropology that focuses on human variation and evolutionary history.

  • Slatkin, M. 1985. Gene flow in natural populations. Annual Review of Ecology and Systematics 16:393–430.

    DOI: 10.1146/annurev.ecolsys.16.1.393

    Review article that provides a thorough discussion on the history and mathematical modeling of gene flow in population genetic analysis.

  • Slatkin, M. 1987. Gene flow and the geographic structure of natural populations. Science 236.4803: 787–792.

    DOI: 10.1126/science.3576198

    Science article providing a brief overview of gene flow and migration in population genetic analysis.

  • Wijsman, E. M., and L. L. Cavalli-Sforza. 1984. Migration and genetic population structure with special reference to humans. Annual Review of Ecology and Systematics 15:279–301.

    DOI: 10.1146/

    Review article covering the role of gene flow and migration in population genetic analysis, with a focus on modern human evolution.

  • Zimmer, C., and D. J. Emlen. 2013. Evolution: Making sense of life. Greenwood Village, CO: Roberts.

    A general overview of evolution, including sections on gene flow and the importance of isolation for speciation.

back to top

Users without a subscription are not able to see the full content on this page. Please subscribe or login.

How to Subscribe

Oxford Bibliographies Online is available by subscription and perpetual access to institutions. For more information or to contact an Oxford Sales Representative click here.