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Migration and population isolation is one of the four evolutionary forces (along with natural selection, genetic drift, and mutation). The study of the distribution of and change in allele (gene variations) frequencies under such influences is the discipline of Population genetics.
The movement of populations in modern times has continued under the form of voluntary immigration/ emigration and involuntary population transfer effected by states. There's also seasonal human migration related to agriculture. Daily human commuting can be compared to the diurnal migration of organisms in the oceans. See Phototropia.
This article concentrates on the historical human migrations.
Human migration has taken place at all times and in the greatest variety of circumstances. It has been tribal, national, class and individual. Its causes have been climatic, political, economic, religious, or mere love of adventure. Its causes and results are fundamental for the study of ethnology, of political and social history, and of political economy.
In its natural origins, it includes the separate migrations first of Homo erectus then of Homo sapiens out of Africa across Eurasia, doubtless using some of the same available land routes north of the Himalayas that were later to become the Silk RoadThe Silk Road ( Traditional Chinese: ; Simplified Chinese: ; pinyin: si chou zhi lu) was an interconnected series of routes through Southern Asia traversed by caravan and ocean vessel, and connecting Chang'an, China with Antioch, Syria, as well as other p, and across the Strait of GibraltarThe Strait of Gibraltar is the strait which separates the Atlantic Ocean from the Mediterranean Sea. On the northern side is Spain and Gibraltar, on the southern side Morocco and Ceuta ( Spain too). Its boundaries were known to antiquity as the Pillars of.
The pressures of human migrations, whether as outright conquest or by slow cultural infiltration and resettlement, have affected the grand epochs in history (e.g. the fall of the Western Roman Empire); under the form of colonizationColonization sometimes colonisation is the act, by a militarily strong country, of invading and taking over the sovereignty of another area, which then becomes known as a colony''. This often includes the establishment of one or more settlements, also cal, migration has transformed the world (e.g. the prehistoric and historic settlements of Australia and the Americas). Population genetics studied in traditionally settled modern populations have opened a window into the historical patterns of migrations, a technique pioneered by Luigi Luca Cavalli-SforzaThe classification into races has proved to be a futile exercise. Luigi Luca Cavalli-Sforza (born January 25, 1922) is an Italian population geneticist born in Genoa, and currently teaching since 1970 as emeritus professor at Stanford University. One of t.
Forced migration (see population transfer) has been a means of social control under authoritarian regimes, yet under free initiative migration is a powerful factor in social adjustment (e.g. the growth of urban populations).
Map of early human migrations according to mitochondrialMitochondrial DNA mtDNA is DNA which is located not in the nucleus of the cell but in the mitochondria. Mitochondria are parts of the cell that generate fuel in the form of adenosine triphosphate (ATP), which drives the varied machinery of the cell. Unlik population genetics (numbers are millennia before present).
The evolution of Homo sapiens occurred in Africa, where, it seems, the first anatomically modern humans developed. Our most recent common ancestor, whom all living human beings share, lived some 150.000 years ago. It is thought that a part of the Homo sapiens population then migrated into the Near East, spreading east to Australasia some 60.000 years ago, northeastwards into Europe and eastwards into Asia some 40.000 years ago, and further east to the Americas ca. 30.000 years ago. Oceania was populated some 15.000 years ago.
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