However, if only one member of the pair considered the other a friend, obesity was more likely to spread only to the person holding that view. (scientificamerican.com)
If either member of a pair failed to dance, we repeated the recording session using the same pair, or switched their partners. (nature.com)
Dogs also have a good scent memory that can identify other dogs they haven't seen for years — and can remember which of them was the dominant member of the pair. (soonervet.net)