Personal needs for space are largely based on environment and culture. For example, those in Latin and Japanese cultures require less space than say Nordic cultures and this is based simply on the raw density in which the people reside. Personal spaces needs are therefore not inherent, but are instead cultural and learned. Cultures that require more space than average include Australians and Mongolians whom are the least densely populated independent country of the world. Cultures that require less space include: Italians, Japanese and Indians since the generally inhabit greatly populated countries. More to this, is the fact that those who grew up in more rural settings such as farmers require even more space than those who grew up in cities.
Here is a breakdown of cultural norms by region:
[A] North Americans and West Europeans. Talk at a distance where outstretched arms might touch at their fingertips.
[B] Russians. Talk at a distance whereby the wrists of outstretched arms touch.
[C] Latin Americans, Italians and Arabs. Talk at a distance where the elbow could touch the body of the other.
Just by knowing that these differences occur affords us a greater understanding and tolerance of other people across cultures which can allow us to treat guests appropriately or give us hints about what we can expect from our host country when traveling. Another factor that controls personal space preferences are environment in nature. Crowded pubs or malls, or even elevators, produce a different set of expectations in all people despite their cultural preferences. Even rural inhabitants know that a full five foot buffer, or greater, is not always possible. Gender also plays a role where females generally prefer a larger buffer between themselves and strangers especially when that stranger is male and conversely tolerate and sometimes even appreciate smaller buffers between close female friends. Some trains for example are specially designated to only carry female passengers to prevent men from enter their personal space especially by men. This luxury guarantees women the safety and privacy routinely enjoyed by men. Men, on the other hand, will generally stand further away from other men then the norm, and permit women to stand closer.