The history of humanity is a history of migration, according to Harzig and Hoerder (2009). They continue to emphasize that there is no “prehistory” of unstable and illiterate peoples followed by the “proper history” of stable empires or nations. Periodization differs between macro- and microcultural regions, but Harzig and Hoerder (2009) generalize eight distinct eras of migration over time: Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Migration of Homo sapiens from East Africa around the world Migrations in the period of early sedentary agriculture, 15,000 - 5,000 BC Differentiating migrations during urbanization in Mesopotamia, Egypt, Indian and East Asian societies, and the world Phoenician-Hellenistic-Roman MediterraneanMigrations from 500 BC to 1500 ADMigrations, intercultural contacts and commercial circuits in the macro-regions of the world, 1400-1600Dalectics of migrations in colonizing and colonized societies, 1600 – 1800,7. global migratory systems of the 19th century, migrations of the 20th and 21st centuries. As Massey (1990) argues, the factors that influence the onset of migration may be very different from the conditions that cause migration to continue, that is, to perpetuate. After an initial phase of pioneering migration, migration becomes more common in the community, with more and more people imitating current migrants and being helped by them until migration becomes self-sustaining. There are several aspects of migration perpetuation, including social capital, social networks, migration institutions, and cumulative and circular migration. Rubenstein (2014) states that people decide to migrate due to push and pull factors. A push factor causes people to move from their current location, while a pull factor causes people to move to a new location. Since migration for most people is a major step not to be taken lightly, both push and pull factors typically play a role. To migrate, people see their current place of residence so negatively that they feel pushed away, and they see another place so attractively that they feel attracted to it. He continues to state that three main types of push and pull factors can be identified: economic, cultural and environmental. Economic Migration Economic migration is defined as the choice to move to improve one's standard of living by obtaining a better paid job. Taking a recent example, when Poland and seven other Eastern European countries joined the EU in 2004, the UK welcomed many economic migrants. In 2009 there were 500,000 workers from Eastern Europe. Pull factors included salaries five times higher than they could get in their own country. Some come for seasonal work, such as picking fruit and vegetables. Higher-skilled migrants may seek medical or educational jobs. The economic effects of migration vary widely. Source countries may experience both gains and losses in the short term, but may gain in the long term. For recipient countries, temporary worker programs help fill skills shortages, but can reduce domestic wages and increase public welfare burdens. The economic effects of migration for both countries of origin and destination can also vary depending on who moves, particularly with regards to the skill levels of migrant workers. A Swedish professor observes: “the problem is not immigration; it is integration, especially in the job market. If there are no seats.