Photo: CNImaging/Photoshot

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When the hilarious, heartwarming book Unlikely Friendships came out this month—documenting a rhino and a goat that were best buddies, as well as an orangutan and a tiger cub, not to mention a snake and an exceptionally trusting hamster—we were instantly reminded of very human "odd couples" we've observed at restaurants, befriended on vacation or even been in ourselves. Captured in their moments of zoological intimacy, each animal duo provides a new kind of insight as to why love sometimes works (and sometimes doesn't) in unlikely situations. Consider this our homage to the universal nature of romance—be it furred, feathered, finned or Homo sapiens.