In parts of the Middle East, the thumbs-up roughly translates to “up yours.” Flashing the two-fingered peace sign in the U.K. means something, um, less than peaceful. The okay sign can be read as a homophobic slur in Greece. In Vietnam, crossing your fingers is considered a vulgar representation of the female anatomy.
There are plenty of motions, in other words, whose symbolic meanings are location-dependent; one country’s friendly hand signal is often another’s grave insult. But there are others, as Becca Cudmore recently reported in Nautilus, that aren’t bound by culture or context — or even species. Some signs, she wrote, seem to be universally understood by both humans and our closest animal relatives: We gesture just like apes do, a fact that scientists are using to study how we learned to communicate with gesture in the first place.
One of those scientists is Richard Byrne, an evolutionary biologist at the University of St. Andrews. In July, Byrne published a paper in the journal Psychonomic Bulletin and Review arguing for “a possible intermediate stage of gestural protolanguage” in our primate ancestors, sometime before we diverged from the apes and developed speech. At a recent presentation, Cudmore wrote, Byrne demonstrated a few gestures to support the theory:
Byrne stretches his right arm far out, hand cupped and face up. What does that signal? Obvious: “Give me.” It’s begging, and very popular among the apes. To Byrne, it’s a legacy of our great ape lineage, some 15 to 20 million years old…
He plays another video that was shot in Bugando, this one of a chimp “flicking” at another in an undeniably annoyed manner… “Get lost creep,” someone from the (University of Vienna) audience pipes in to narrate the chimp’s flick. Byrne laughs, “Yeah, exactly,” he says. “I don’t think any of you actually use that gesture”—the audience starts to whisper and laugh indicating that this might not be true—“yet you nevertheless know what it is.”
Other scientists, though, argue that there’s an alternative explanation for the overlap: the simple fact that our bodies are structured the same way. Stomping and punching out of anger, for instance — a behavior seen in both apes and humans — may just be a function of our similar mechanics. “Given the way that the human body works, when you bang on something, you bang with your hand or your foot,” cognitive scientist Richard Moore told Nautilus, “not your knee or your chin, because that’s how we’re built.”