The advent of YouTube and other Internet video sites has brought us a glut of cute animal clips. It’s no longer enough to gush over adorable kittens. You have to see sweet little critters in unlikely tandems, like a cheetah cub that has become best friends with a Labrador retriever.

”Nature” (7 p.m., PBS) presents “Animal Odd Couples.” This being public television, it’s not enough to show such cute combinations. We have to ask how and why young lions get along with coyotes. Or why a photographer’s dog befriended an orphaned fawn in the wild. What does this say about animal cognition? Can critters feel something close to empathy with creatures they might just as well be chasing, hunting or devouring?

Among those cited here are Temple Grandin, famed animal behavior expert (and subject of a superb HBO film biography, starring Claire Danes). She thinks that research is beginning to show us a lot more about the emotional life of animals. Or, as she puts it, “I think scientists are going to prove that little old ladies in tennis shoes who say that little Fifi really can think are right.”

Tonight’s other highlights:

• After his arrest on murder charges, Oliver wants Laurel to act as his attorney on “Arrow” (7 p.m., CW).

• Jay’s first wife (Shelley Long) returns on “Modern Family” (8 p.m., ABC).

• Actress Debi Mazar and her husband, Gabriele Corcos, return to the third season of their culinary series “Extra Virgin” (8:30 p.m., Cooking).

• Krissy’s behavior falls under scrutiny on “The Houstons: On Our Own” (8:30 p.m., Lifetime).

• Russell’s son becomes a murder suspect on “CSI” (9 p.m., CBS).

• Casey’s confrontation with Voight has consequences on “Chicago Fire” (9 p.m., NBC).

• “Moonshiners” (9 p.m., Discovery) returns for a second season.

• Deacon consoles Juliette and begins to irk Rayna on “Nashville” (9 p.m., ABC).

• A new patient has clues to Arden’s past on “American Horror Story: Asylum” (9 p.m., FX).

• The new series “LOLwork” (10 p.m., Bravo) steps inside the office of an Internet comedy publisher that attracts millions of views with purposefully inept captions attached to — what else? Cute pictures of pets and animals.