Demic diffusion is a demographic term referring to a migratory model developed by Cavalli-Sforza, that consists of population diffusion

Diffusion

Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...

 into and across an area previously uninhabited by that group, possibly, but not necessarily, displacing, replacing, or intermixing with a pre-existing population

Population

A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...

 (e.g. as has been suggested for the spread of agriculture

Agriculture

Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 across Neolithic

Neolithic

The Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BC in some parts of the Middle East, and later in other parts of the world. It is traditionally considered as the last part of the Stone Age...

 Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, and what occurred with the European colonization of the Americas

Americas

The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

).

In its original formulation, the demic diffusion model includes three phases, namely: (1) population growth, prompted by new available resources as in the case of early farmers, and/or other technological developments; (2) a dispersal into regions with lower population density; (3) a limited initial admixture with the people encountered in the process.

Evidence

Theoretical work by Luca Cavalli-Sforza showed that, if admixture between expanding farmers and previously resident groups of hunters and gatherers is not immediate, the process would result in the establishment of broad genetic gradients. Because broad gradients spanning much of Europe in the Southeast-Northwest direction were identified in empirical genetic studies by Cavalli-Sforza, Robert R. Sokal

Robert R. Sokal

Robert Reuven Sokal is an Austrian-American biostatistician and anthropologist. Distinguished Professor Emeritus at the State University of Stony Brook, New York, Sokal is a member of the National Academy of Sciences and the American Academy of Arts and Sciences...

, Guido Barbujani

Guido Barbujani

Guido Barbujani is an Italian population geneticist, evolutionist and literary author born in Adria, who has been working at the State University of New York at Stony Brook , at the Padua and Bologna Universities, and is now a professor at the University of Ferrara since 1996.-Works:A population...

, Lounès Chikhi

Lounès Chikhi

Dr Lounès Chikhi is a French population geneticist of Algerian Berber extraction, based at the Université Paul Sabatier in Toulouse, France, and also at the Instituto Gulbenkian de Ciência in Oeiras, Portugal, where he runs the ....

 and others, it seemed likely that the spread of agriculture into Europe occurred by the expansion and spread of agriculturists, possibly originating in the Fertile crescent

Fertile Crescent

The Fertile Crescent, nicknamed "The Cradle of Civilization" for the fact the first civilizations started there, is a crescent-shaped region containing the comparatively moist and fertile land of otherwise arid and semi-arid Western Asia. The term was first used by University of Chicago...

 of the Near East

Near East

The Near East is a geographical term that covers different countries for geographers, archeologists, and historians, on the one hand, and for political scientists, economists, and journalists, on the other...

 region. This is referred to as the Neolithic demic diffusion model.

Craniometric and archaeological

Archaeology

Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...

 studies have also arrived at the same conclusion.

External links

• Estimating the Impact of Prehistoric Admixture on the Genome of Europeans, Dupanloup et al., 2004
• Origin, Diffusion, and Differentiation of Y-Chromosome Haplogroups E and J: Inferences on the Neolithization of Europe and Later Migratory Events in the Mediterranean Area, 2004
• Y genetic data support the Neolithic demic diffusion model, Chikhi 2002.
• Paleolithic and Neolithic lineages in the European mitochondrial gene pool, Cavalli-Sforza 1997.
• Clines of nuclear DNA markers suggest a largely Neolithic ancestry of the European gene, Chikhi 1997.

See also

Cultural diffusion

Cultural diffusion

In cultural anthropology and cultural geography, cultural diffusion, as first conceptualized by Alfred L. Kroeber in his influential 1940 paper Stimulus Diffusion, or trans-cultural diffusion in later reformulations, is the spread of cultural items—such as ideas, styles, religions, technologies,...

: the spread of culture via interaction between individuals from one culture to another or within a culture