Monkey see, monkey do. Baby humans and apes both bond with their parents by mimicking facial expressions. Now researchers report in the September issue of PLOS Biology that infant monkeys also get in on the act: for up to 7 days after birth, rhesus macaques will imitate humans smacking their lips, opening their mouths, and sticking out their tongues. The findings indicate that emulation by newborn primates evolved earlier than previously thought. (Photo: Ferrari et al., PLoS Biology)