Culture Clashes Encourage Immigration.

It is good to learn something new and unexpected about a subject which you believed you had thought about it some depth. The economist Paul Collier's book about immigration, Exodus, revealed something counter intuitive but actually very logical about how immigration works:

All things being equal, more immigrants will come from cultures that integrate poorly into the host society than from those that integrate well. 

This is surprising but makes sense when considering it from the point of the migrant. It is known that the presence of a diaspora facilitates the ease with which people can settle in a country, so if a community integrates quickly into society there will be little or no diaspora with extremely close ties to the country of origin, which will slow down migration. This makes sense, there is no functioning Australian diaspora in the UK beyond first generation short term migrants because our cultures are so close that integration is nearly inevitable, on the other hand there is a distinct Bengali diaspora that acts as a magnet for further Bengali immigration.

The implications for immigration policy are profound, without either restrictions on immigration or some method of hastening integration, migrants will, over time, come from cultures that are hardest to integrate into society.