Many years ago, I learnt of the concept of "personal space" - the idea that people carry a small territory around them that they do not like strangers to invade.
In particular, the size of one's personal space is claimed to be inversely related to the population density of one's culture.
I probably read about it in some variant of the Pease's Body Language franchise.
Here's one (plagiarised?) source:
Like most animals, each human has his own personal Portable 'air bubble', which he carries around with him; its size is dependent on the density of the population in the place where he grew up. Personal Space is therefore culturally determined. Where some cultures, such as the Japanese, are accustomed to crowding, others prefer the 'wide open spaces' and like you to keep your distance.
As mentioned, the amount of Personal Space someone needs is relative to the population density where they live. People raised in sparsely populated rural areas for example, need more Personal Space than those raised in densely populated cities. Watching how far a person extends his arm to shake hands gives a clue to whether he is from a large city or a country area. City dwellers typically have their private 18-inch (46cm) 'bubble'; this is also the measured distance between wrist and torso when they reach to shake hands.
Here is another (copyright infringing?) source (from slide 19) attributing similar words to Allan Pease.
Note: An anecdote about different cultural expectations has quietly changed from Danish to Italians between the two stories, which should ring alarm bells about its veracity.
In my experience, on the rare occasions I have found people who don't respect the social norms of my personal space, they have turned out to be from similar - or even slightly more rural - cultures to me. [Sampling bias alert - that probably accounts for most of the people I meet in person.]
So, to my question:
Is there a relationship between the population density in the area a person grew up, and their preferred distance apart when standing with others?