There are two common-use meanings for this term: diaspora and Diaspora.
The ‘little d’ diaspora refers to any (more-or-less) peaceful migration or immigration or general re-settlement of a socially cohesive group of people with a well-defined social identity into an already populated area, with no intention of integrating into the host society. The ‘capital D’ diaspora refers to one specific ‘little d’ diaspora: the expulsion of Jews from Jerusalem by the Romans and their resultant scattering around the World.
At this point, I am only focusing on ‘little d’ diaspora.
This ‘diaspora’ is a curious concept: a group of people who share a common ancestry/language/culture/religion – such as a tribe, or a clan, settle in an area already inhabited by ‘different people’. Once there, they do not attempt to gain the land by conquest: they either legally purchase it or, if the population density is low, they simply settle there and eventually claim squatter’s rights. So, there is no war.
The ‘newcomers’ are usually not perceived as hostile, so the people in the ‘host culture’ do not harbour hostility towards them. Or, at least, not particularly so. At the beginning.
But, we, humans, have come to be who we are by following a certain path of social evolution.
Each one of us is, first and foremost, an individual. And, even in the most collectivistic of human societies, there is an acknowledgement (or a lament) that we are, indeed, individuals.
This fact that each of us is an individual does not, in any way, change that we are also very social: we nurture our young and have long learned that pooling our resources can help us survive and succeed. We don’t always agree on how much of our resources ought to be pooled, and how this pooling ought to be accomplished – but that is a different matter.
Different human societies have indeed reached different states of balance (or, imbalance) between the ‘individual’ and ‘society’. This is only to be expected, because humans are such a prolific organism that we thrive – or, at least, survive – in greatly varying regions of the world. These produce very different pressures (stresses) on the different human groups and their social rules that they govern themselves by. Thus, very different attitudes, moral codes and social rules had developed.
Many people I have talked to seem to think that there is some sort of a ‘universal’ set of rules of ‘morality’ that all people subscribe to. I am sorry to disappoint these people: there is no such thing. It is only because most cultures which had, historically, interacted with each other had been ones which were also in physical proximity: thus, both a similar set of environmental pressures and long-term contact (such as trade) between the cultures served to spread ideas, learn of each other’s attitudes – in short, served as a ‘normalizing’ pressure on the development of these cultures. This then gives an ‘appearance’ of ‘universal’ concepts of ‘right and wrong’.
Thus, this ‘universality’ is no more than an appearance. What worked for one group of people in one specific time and place became their set of ‘right and wrong’. Sure, if they learned a rule that seemed to produce better results, they usually found a way of incorporating this new rule into their society. (Often, this was in the form of a new deity – which is why so many monotheistic cultures seem to freeze in their ‘moral’ development… but THAT is a completely different post!)
Isolated cultures are prime examples of just how different ‘right and wrong’ is, depending on the pressures on the society. Most ‘mainland’ cultures prospered if there were more offspring: the more babies born, the more were likely to survive and become productive members of their clan, the better the clan did. So, in most of these cultures, homosexuality (actually, most activities which would divert natural sex-drive away from baby-production) was forbidden and became considered ‘immoral’. I remember my Anthropology prof telling us about an isolated culture on a small South Pacific island, where the overpopulation was the stress which drove the development of the society. On this island, homosexuality was not only permitted, it was considered to be morally superior to heterosexuality! As a matter of fact, heterosexual sex was taboo for over 300 days of the year…
The same is true of ‘murder’ – the concept of ‘killing another human being’ as ‘bad’ or ‘immoral’ is actually not all that common… as I have ranted on before.
As any physician will readily confirm, our brains are not any different from those of our bronze-age ancestors. Sure, when we have better nutrition and vitamins, when we grow up mostly free of diseases, our brains develop into a much fuller potential then they would otherwise. But not all our ancestors were malnurished or ill…. Our brains are have the very same physical characteristics, the same ‘blueprint’, if you will, that the brains of our bronze-age-ancestors did.
What differentiates us from our ancestors is our culture – our learning and our social attitudes. In other words, ‘culture’ is what ‘defines us’ as ‘us’.
As opposed to ‘them’.
And this ‘them’ concept is extremely important to the way our ‘bronze-age blueprint-of-a-brain’: because in our bronze-age past, ‘them’ could never really be trusted! The simple fact that ‘they’ were not ‘us’, but ‘they’ meant that ‘they’ did not have a vested interest in ‘our’ survival.
That is why so many ‘ kings/chieftains’ would marry a daughter of a king/chieftain with whom they had just reached a peace-treaty: the ‘father-king’ would have a vested interest in the survival of his grand-children, just as the ‘bride-groom-king’ has a vested interest in the survival of his own children. This marriage and its ‘blood-bond’ reduces the ‘they’ factor and makes both sides see the other as at least a little bit more part of ‘us’.
Which brings me back to the ‘diaspora’: the very point of a diaspora is that the newcomers do not become part of the ‘us’ which surrounds them. By the very definition of the word ‘diaspora’, these newcomers have a fully formed cultural (which includes religious) identity of their own and are not willing to compromise it in any way – especially through mingling of the blood!
In other words, the newcomers – by their choice – do not become ‘us’ to their neighbours/hosts.
This results in both sides being unable to fully trust each other: blame our ‘bronze-aged brains’!