Finalists: Love in Infant Monkeys by Lydia Millet (Soft Skull Press) and In Other Rooms, Other Wonders by Daniyal Mueenuddin (W.W. Norton & Company) (bookpage.com)
An interesting example from primate studies relates to dogs as surrogate mothers for infant monkeys. (siriusdog.com)
Experiments that separate infant monkeys from their mothers cause profound and unnecessary suffering. (scientificamerican.com)