Spotted hyenas grunt and growl. But you know what they're famous for. So what's all the laughing about? Well, field researchers have noticed that groups of hyenas tend to giggle around a kill, while they're waiting for their hunk of meat. Now a study in the journal BMC Ecology says the chuckles may communicate things like age, identity and social status. Which is important stuff for figuring out who gets the tastiest cut of zebra. Researchers studied a clan of spotted hyenas living in a sanctuary behind the U.C. Berkeley campus. They enticed 17 hungry hyenas with bones or pieces of meat, and recorded about 250 bouts of giggling. Then they ran those sound bites through various computer algorithms, running statistical analyses and drawing up spectrograms. The result? They say a giggle's pitch and timbre establish a hyena's identity, and that pitch indicates age. But the giggle also tells you who's boss. A relatively monotone giggle and you're first to the meat. A more erratic, variable giggle? Get back in line. The researchers next plan to study hyenas in the wild. Just for laughs.