Also, MS Word auto-corrects <space>-<space> into an em-dash just like it fixes quotes. Depending on which software was used to write it, it's very likely that's what happened.
I'm never suspicious of only one em-dash, as they are a perfectly valid, if infrequent punctuation. Three or more in an article this length would make start looking at the rest of it more closely, though.
I'm never suspicious of only one em-dash, as they are a perfectly valid, if infrequent punctuation. Three or more in an article this length would make start looking at the rest of it more closely, though.