So, when I was very much younger, and aspiring to hang with slightly older, much cooler conspecifics, I used to admire how very taciturn and low-key these cool guys were. They would be hanging out together in a group, looking very lazy and unconcerned. Even when someone they liked showed up, it’s not like they would go say hello or shake the guy’s hand or whatever. The most they could muster, from the depth of their lassitudinousness, was to kind of raise an eyebrow while saying nothing, like in the most minimal recognition of a slightly cool arrival event, which event was endorsed as mildly better than all the boring shit that had been happening lately.
So I seriously remember feeling that these guys were cool, and that their manner was something unique and to be emulated. Imagine my surprise and displeasure to find out that raising your eyebrows briefly in greeting was not a) an innovation of my social circle, or b) an innovation of my cultural circle, or c) an innovation of my national or ethnic group, or d) an innovation of humanity, but: a _primate_ _universal_.
That’s right: I don’t know exactly how far this spreads throughout the primate world, but it turns out that that many species share the following behavior: when a new member arrives, friends will very quickly raise and then lower their eyebrows, just to say hello. (Of course, for many of these species, this is very convenient, because they don’t have language qua language, so they _can’t_ say hello.) The upshot though is that, since this behavior is shared across many species, it no doubt has evolutionary roots that go back before those species split off from each other, so … deep roots indeed.
So the funny thing is that, once you become aware of this kind of thing, it’s difficult to know how to respond to that knowledge. Do you renounce the primate eyebrow flash? If so, imagine the following scenario: you’re at a party, and across the room (so you can’t speak) you see a long-lost and valued friend. Imagine that you have taken a vow to neither wave nor raise your eyebrows in greeting. What happens next? Possibly your friend sees your impassive face across the room, and then wonders … hmm, what’s up?, I thought we were friendly?