动物之乐：科学家如何测量动物的积极情绪

Scientists have long focused on quantifying fear and other negative emotions in animals. Now they’re trying to measure positive feelings — and it’s a challenge. By Amber Dance Well, of course — just look at my tuxedo cat, Tango. He has an evening ritual: He waits atop the bed for his brother Teddy, a fat orange tab- by with a remarkable resemblance to a loaf of French bread, to stroll by. Then Tango reaches out to snatch at Teddy’s tail with apparent glee. As animals ourselves, we think we see happi- ness in our fellow creatures all the time. …