I just remembered that apes smile when hostile. This isn’t a happy scene. This monkey has full meter and a full screen projectile in it’s move list. This is an invitation to death.
Humans have this distress response too! If you watch the smaller of their young you will spot the occasional baring of teeth in upsetting situations. You can see this with adult humans as well, but it’s harder to catch because they have a fairly deep somatic vocabulary assigned to smiles; it is probably easiest to recognise after minor injury like stubbing a toe or receiving an injection.
It’s a lot of fun comparing how related species have related behaviours, and also neat to contrast how they have specialised them!
this is interesting but
If you watch the smaller of their young
why did you word it like that
Thanks for the question! My area of expertise is more generally avian than it is mammalian (or primate), so I don’t really know the technical nomenclature for the specific stage of human offspring development I mean to communicate.
With the vocabulary I have the closest I can get semantically is ‘mid-nestling to fledgling fresh-fallen from the nest’ but the concepts don’t quite map to how human offspring develop. Another way to phrase it is able to move around under their own power but still heavily dependent on parental intervention for survival.
Hope this helps clear things up! Have a nice day :)
You studied birds so long you forgot that the word toddler exists and I think that’s just delightful.
So funny thing with primates (especially apes) is that they “smile” in a number of ways. And it’s way more nuanced than you think. (This is what happens when an intelligent social species relies heavily on non-vocal social cues).
1.The play face smile. Here we see the relaxed open mouth with a droopy lower lip exposing the bottom teeth. Often accompanied by low guttural chimp laughter. This face is both an invitation to play and a way for individuals to check in and make sure everyone is still having a good time while playing. You younger siblings out there know how “playing” with your elder brother/sister is all well and good until “it’s Not Funny Anymore Cause That Really Hurt, Twin!!!” (No? Just me? Damn.)
2.Silent bared teeth display which can be an appeasement gesture / sign of submission as they try to avoid possible conflict. Tense mouth and at least partially exposed upper & lower teeth. This is kinda on a spectrum and go from something little like “hey that termite mound snack looks good, can I get in on that too?” all the way up to…
3.The Fear Grimace. It is what is sounds like. “I am afraid and I don’t want to fight. I’m submitting. Please don’t hurt me.” Mouth may be somewhat open, lips are tense and retracted, and teeth very visible (possibly with some partial gum exposure). See the female below on the right who is fear grimacing at her screaming friend.
4.The scream. “I’m upset and I DO NOT LIKE THIS!!!!” Fight or flight is going down and screaming animal is in the thick of it. Lips are completely retracted, full teeth & gum exposure, and mouth is open in a loud scream vocalization. See the female on the Left in the above photo as she screams at something (/someone) off camera.
5.Neutral face. Talk about going from the highest high to the lowest low. This is a chill happy primate at a low arousal state. Casual relaxed face and eyes. Not challenging anyone, but not seeking out a particular grooming/play buddy either. Just watching the world go by for a bit.
This is just a general example of the gorgeously nuanced field of facial communication in primates. If I had to pick (without audio / video / context clues) I would say the bonobo in the OP is doing a silent bared teeth display begging for something towards shore (thus the extended hand) possibly edging more towards a fear grimace. They aren’t exhibiting any overt aggression, but that by no means makes them safe to be around.
Please let me know if you have any questions.
Love,
Your friendly neighborhood Ethologist / Primatologist
Sources:
Marina Davila-Ross, Goncalo Jesus, Jade Osborne, Kim A. Bard. Chimpanzees (Pan troglodytes) Produce the Same Types of ‘Laugh Faces’ when They Emit Laughter and when They Are Silent. PLOS ONE, 2015; 10 (6): e0127337 DOI: 10.1371/journal.pone.0127337.
Parr LA, Waller BM. Understanding chimpanzee facial expression: insights into the evolution of communication. Soc Cogn Affect Neurosci. 2006;1(3):221-228. doi:10.1093/scan/nsl031.
