ARE WE SPECIAL?

Scientists have long debated the traits that differentiate Homo sapiens from other extinct hominids like Neanderthals, primate cousins and all other animals. Like toolmaking, some of the abilities once considered exclusive to our species have turned out not to be. Others remain on our collective resumé — at least for now.

Art The recent discovery of 40,000year-old cave art in Indonesia, matching the oldest known in Europe, suggest that Homo sapiens may have been carrying on a practice developed by an earlier ancestor. Cave paintings and engravings have been attributed to Neanderthals, our extinct human cousins, but remain controversial.

Language The distinctions between animal communication and human language are a long-standing matter of debate. Mathematical analyses of the noises made by birds, bats, whales and others found vocalization patterns much more complex than expected.

Fire Israeli scientists have argued that the oldest evidence of habitual fire use lies among 350,000-year-old charred flints in a cave near Haifa, suggesting that some unknown human ancestor was the first to control fire, but not necessarily Homo sapiens.

Posture Lucy, the famous fossilized Australopithecus discovered in 1974, demonstrated in stunning fashion that walking upright came before big brains, in terms of the adaptations that separated our lineage from the apes. The reason for this crucial evolutionary change is still debated, since it came at a cost: upright anatomy makes childbirth far more difficult.