We have some Tuesday felids because this video, taken at the Tulsa zoo, demonstrates an evolutionary lesson. Look closely at the cubs’ coats, and you’ll see leopard-like rosettes. Many species of cats show this pattern in the cubs, even if the pattern disappears with growth. It almost certainly reflects (as discussed in WEIT), an atavistic trait: the persistence in a descendant of traits that were adaptive only in an ancestor. I suspect that the ancestor of lions had spots as adults, and that’s why they show up, briefly, in lion cubs.