A white crowned sparrow is just beginning to fledge, surrounded by a barrage of birdsong from its own species and others. As long as it is sufficiently exposed to its own specie's song during this stage, it will be able to learn that song when it matures. If it is kept isolated, the bird will never learn- even if it is exposed to the song ages later.
A human infant, in its first year, is exposed to a variety of calls too- from its parent's, from television characters, even pets. Yet even if speech has not fully formed by their first birthday, a child will have committed to its native language- any vocal sounds it has not been sufficiently exposed to during this time, even if they are common to other languages- will be impossible for the child to comfortably produce, if not impossible.
Although humans and birds diverged ages down the evolutionary ladder, striking resemblances between the way babies learn a language form copying their parents and songbirds learn their species' calls from tutors have urged researchers to look more closely at how birds learn songs for clues at the origin of vocal language. The process is so complex, even if it evolved separately between the two species, one system might well resemble the other. And besides, where else could vocal language have come from?
Answer: where non-vocal language came from.
Scientists have long studied apes for clues on language (our ancestors make a natural choice.) But have been frustrated by ape's inability to pick up language. Though they might learn complicated gestures (such as sign language) and use that to communicate pointedly and easily, after a lifetime of trying you might, if you're lucky, get one to understand three words. But gesture might be more closely linked to vocal language than previously thought. The language centers of the brain are located on the left side, which also coordinates movements on the right hand side of the body. Apes (and humans!) have a strong tendency to use their right hand for communicative gestures, such as those showing information or interest. This holds true even if the animal/person in question is ambidextrous or left handed! Yet there is no such tendency for non-communicative gestures like head-scratching. This suggests that gestures are done with the right hand because they are linked to the language-centric parts of the brain. And here's where it gets really interesting: if you separate pointing into two categories, imperative (for "I want this, begging, etc.") and declarative (which shares information, requires seeing the other person as a PERSON, and is accepted as higher-level communication), then declarative pointing is much more often accompanied by a word or call than imperative pointing! It seems like higher-level communication (through gestures) naturally leads to vocal language!
Perhaps language originated from gesturing, and as evolution took its course it became mostly or entirely vocal in some species. Who knows, maybe if it was advantageous humanity would evolve beyond gestures entirely. So where did language originally come from? No one is sure. But it seems like if we want clues on how it works now we should look to our avian cousins, and if we want to know how it worked then we should learn from our ape ancestors.
- Alice Trei
This is a really cool comparison. The fact that the left side of the brain controls language and movement of the right side of the body is really interesting when you think about the apes signing. i wonder if they would try to sign to other apes and what their response would be if that ape did not understand?
ReplyDeletePosted by Amber Kapchinske
Thank you.
ReplyDeleteI think it would be determined by:
a. the message they were failing to understand
b. the ramifications of them not understanding it
c. the connection or social differences between the two apes- if an alpha doesn't understand a younger one then the younger one might not do anything, but if the alpha asks for something and doesn't get it there might be fighting.
If the receiver really couldn't understand, even after the signal is repeated, then either the communicator would have to do something, or walk away. It reminds me of the non-communicative pair of seagulls we saw in that video, where their reproductive success was compromised because the female did not understand the male.
-Alice