I think this was a part of the story in the sci-fi novel "Stand on Zanzibar" by John Brunner. The title refers to the fact that (at the time) if you were theoretically able to round up the entire world population and give them just enough space to stand upright then they would fit onto the African island of Zanzibar.

I was a kid when I read it and forgotten the plot but it was something to do with the expanding world population. I should read it again because the author was pretty cool, a sort of earlier Neil Stephenson the "Snowcrash" guy.

In the story there is an explanation of dislike of the sweat smell - it indicates the smell of someone who has recently arrived after travelling a long distance hard and fast and could therefore be a threat.