Mother monkeys permanently separated from their newborns sometimes find comfort in plush toys; this recent finding from Harvard experiments has set off intense controversy among scientists and reignited the ethical debate over animal testing. The paper, "Triggers for mother love," was authored by neuroscientist Margaret Livingstone and appeared in the Proceedings of the National Academy of Sciences (PNAS) in September to little fanfare or media coverage. But once news of the study began spreading on social media, it provoked a firestorm of criticism and eventually a letter to PNAS signed by over 250 scientists calling for a retraction. Animal rights groups meanwhile recalled Livingstone's past work, which included temporarily suturing shut the eyelids of infant monkeys in order to study the impact on their cognition. "We cannot ask monkeys for consent, but we can stop using, publishing, and in this case actively promoting cruel methods that knowingly cause extreme distress," wrote Cath