According to a study, Companies which encourage racial, ethnic, religious, regional and other diversities in their work places are more productive, successful and; as a consequence Happy (Happy employees).
Although, the study limits itself to workplaces generating wealth of some kind, the positive effects of diversity can be seen at other places well.
The countries which encourage diversity in the form of liberal immigration policies are more prosperous, productive, successful. Some examples are USA, Canada, United Kingdom, Singapore etc.
In contrast, closed or single-religion countries such as Pakistan, Afghanistan, Iran etc. are either poor, non-productive or Unhappy in part or in totality. For instance, Pakistan or Taliban ruled Afghanistan may not be a particularly happy place for women. Pakistani school girl and Nobel Prize Laureate Malala Yousafzai is an example of how countries based on a single religion or having the sentiment of a single religion based majoritarianism are a unhappy place for women. The child has to face the bullets of religious extremists to defend her right to school education.
Any country which moves towards a single religion or towards the sentiment of a single religion based majoritarianism, can be said to be moving towards a Taliban of some kind — A place where women have least rights.
The positive role of diversity doesn’t end at work places and countries. People who live in countries and societies where diversity is encouraged are usually more productive, successful and Happy. An example is People Of [other country] origin living in US, Europe and countries where diversity is celebrated. Any immigrant living in USA had not been that successful, if he/she kept thinking about living in a country based on single religion majoritarianism. He/she chose USA because it is the land of diversity. And also the land of opportunity. Whether or not — the respect for diversity makes USA the land of opportunity — can be debated. What is beyond doubt is that USA is both a land of diversity and opportunity. Anyone who migrates to USA from any part of the globe knows this and celebrates the diversity. That’s why he/she aspires to have his work place as diverse as possible. And aspiring so is productive!