Behavioral and brain asymmetries in chimpanzees

Clutching a clipboard, the new lab assistant strides purposefully down the corridor of the great ape wing. As he walks past the row of enclosures, he engages in good-natured banter with the chimpanzees, tossing peanuts as he goes, stopping here and there to engage with some of the more fr iendly apes. But as he approaches one particular female chimpanzees cage, his steps falter, his demeanor becomes more guarded and watchful. He slows to a near-crawl, his confident stride reduced to a slinking, furtive posture. And there she is, ever watchful, waiting for him. Mega is a young adult female chimpanzee. She is not particularly large, nor is she dominant in her group. But where other chimpanzees enjoy throwing the occasional malodorous fistful of feces at people, for Mega it seems a divine calling. With a fistful of excrement clutched in her left hand, Mega becomes a fearsome and terrible menace with the strength of a boxer and the accuracy of a professional baseball pitcher. She even hoards her ammunition, protecting it against the cage-cleaning eff orts of the husbandry staff . Nobody here has escaped her prodigious talent. As the lab assistant approaches, she raises her left hand in the air, oscillating with quiet menace. The lab assistant decides he'll make a run for it. He raises his clipboard as a shield and begins to sprint down the corridor, the tails of his pristine white lab coat flapping behind him. With his first step Mega holds her position, waiting for the exact millisecond of opportunity when the V-neck of the humans surgical gown flashes vulnerably open. And by the second step in his desperate run, she has released her fetid missile, unerringly finding her mark. As the soiled lab assistant trudges past in defeat, he wonders: Why does she always use her left hand when so many of the others use their right?