Research overview: why big cats roar but cannot purr continuously, and vice versa

The roaring big cats and the purring small cats appear to form complementary groups, and this overview reviews the basis and limits of this divide. The flexible, incompletely ossified hyoid and specialised vocal folds of Panthera species are linked to roaring, and these same features are thought to preclude the continuous true purr of smaller cats, which have a rigid hyoid. The snow leopard, a Panthera member that does not roar, complicates the neat split. Researchers compare hyoid and laryngeal anatomy across species. Why it matters: the roar-or-purr dichotomy is a memorable lesson in how anatomy constrains behaviour, but the exceptions show that the relationship is not absolute, prompting careful study of how bone and soft tissue jointly determine which sounds a given cat can and cannot make.