Pagel "et al." also examined two other possible objections to their conclusions. They rule out linguistic borrowing as a significant factor in the results on the basis that for a word to appear cognate in many language families solely because of borrowing would require frequent swapping back and forth. This is deemed unlikely because of the large geographical area covered by the language groups and because frequently used words are the least likely to be borrowed in modern times. Finally, they state that leaving aside closed class words with simple phonologies (e.g. "I" and "we") does not affect their conclusions.