Because we learn to speak from nearby adults, our dialects diverge across geographic lines. It’s even possible to predict where a stranger was raised based on speech patterns alone. Southerners, for example, use “y’all” as the preferred plural of “you,” while South Philadelphians say “youse.” People from different eras also speak differently; you’d get strange looks if you walked around talking like Shakespeare.
But we’re far from the only species that boasts a range of vocal patterns. Sac-winged bats, for example, live across Mexico and South America and have distinct vocal styles across this range. When the female bats disperse to mate, they listen for calls that are similar — enough to indicate familiar food and pathogens — but not identical to those of the group they were born into. Similarly, in California, white-crowned sparrows living just miles apart will often sing different tunes; in rare instances, individuals living at ...
