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Language May Have Evolved Earlier Than Supposed
Science News reports on research suggesting that humans' language ability may have developed earlier than we thought. Scientists used CT scanning of H. heidelbergensis skulls, more than 530,000 years old, to reconstruct the structure of the ear canal of this Neanderthal ancestor. They found evidence that the ears of these early hominids would have had a sensitivity peak in the same 2-4 KHz range that the ears of modern humans do — the range in which most information is carried in language. Sensory systems are neurologically expensive, and it's unlikely that the body would invest the resources in maintaining such a system if it didn't serve a purpose. Quoting: "It may be time to rethink the stereotype of grunting, wordless Neanderthals. The prehistoric humans may have been quite chatty — at least if the ear canals of their ancestors are any indication. The findings suggest human speech may have originated earlier than some researchers contend. Anthropologists disagree about whether language sprang up rapidly around 50,000 years ago or emerged more gradually over a longer period of time..."
Negus wrote a long fairly boring analysis of the larynx which makes such statements painful. (Lots of cross-sagittal sections. Gross but cool.)
Not because they're wrong, but rather because they are just so OBVIOUS.
The position of the tongue in the back of the throat and the movement of the epiglottis upward, away from the larynx are not beneficial -- they're compromises to benefit something else -- a vast increase in phonemes. Language comes right behind (or even ahead of) the upright posture and the migration of the tongue down into the throat.
Furthermore, all this ignores gestural languages. Susan Goldin-Meadow's studies showed that deaf children across many languages and continents, when deprived of sign-language education (yes some families decide to do this), all come up with their own home-grown sign language with key syntactic elements (notably word order) which are exactly the same. Even when the language that their parents speak have different word orders. There's some hard-coded syntax for at least gestural language.
It's possible that gesture is just taking advantage of hard-coded speech language brain-systems. It's likewise possible that language predates speech, and that the migration of the tongue allowed the new upright primates to use their virtuoso noises with their already established language -- which would have been primarily gestural.
Language goes back a LONG, LONG way. It might have been crappy until half a million years ago, but it's way older than that.
So wait, because what emits noise is a certain way, and of certain dimensions, the things that pick up the noise had to change to accommodate? It works both ways.
You're not listening.
The peak hearing range is attuned to the human vocal range. They are a coupled pair. It is not a case of speech being optimized to our hearing, because the speech organs have much more confining physical limitations than hearing organs. Of note here is that the peak sensitivity of women is higher than that of men--and the vocal organ's peak performance is higher as well. We are not physically capable of producing speech in a significantly different range--our vocal apparatus could not evolve to match a peak hearing sensitivity in a different range.
The ear evolved to optimize to the human vocal range's specific limitations. All speech had to do was get inside the 1-10kHz "normal" mammalian range--the human ear can hear well below and above this range, but the vocal apparatus cannot function there.
I imagine that spoken language communication would have adjusted itself to the hearing range rather than the other way around.
No. The human vocal apparatus has significantly narrower physical limits than the human ear. It cannot respond as effectively.
Something that is variable amongst many humans seems most likely to be something that evolution would play with.
That's just it: it's not that variable. What your brain interprets as great variations in frequency are, in fact, relatively minor. Further, your ability to produce sounds outside the midrange of your vocal tract grows exponentially more difficult. Your ability to hear those sounds requires no similar exertion.
wildly/randomly communicating at a certain frequency range
It's neither wild nor random. It is a direct, physical consequence of the structure and size of the vocal organs. It's not coincidental that a kitten makes high pitched, squeaky noises and a lion has a low, reverberant roar.