How Did Human Hearing Evolve?

We’re talking about ancient human hearing! We’re talking about ancient human hearing! We’re talking!! oh forget it. listeners and friends
We’ve spent a lot of time on DNews talking about language and the power of spitting flow
atcha, but no matter how sick your flow, if we hadn’t evolved hearing, it would be lost
on you. Hearing is one of our essential traits, and according to a study from a Jan 2006 issue
of Nature we got our auditory adroitness from fish gills! Our ears have tiny bones which translate waves
of energy pushing through the air from wave energy to mechanical energy, then fluid energy,
before conversion to chemical signals for processing in the brain. But, 370 million
years ago, a fish called Eusthenopteron [Yoos-then-opter-on], had a small bone which had a kink that blocked
the gill opening, and its descendant, Panderichthys [Pander-ick-this] had a slightly wider version
of that bone, called a spiracle. Spiracles allow the fish to breathe air above the surface
while it remains underwater (which in itself is incredible), but scientists think the spiracle
is the missing link between fish gills and land-animal hearing! There are, of course,
a number of evolutionary steps in-between; for example, the hyomandibular [hi-oh-mandib-u-lar]
bone which became the stapes — a stirrup-shaped bone in the middle ear — evolved from a bone
that used to brace the lower jaw of sharks and early jawed fishes. Because of these tiny bones and slow adaptations,
we slowly adapted our own hearing. According to an old study from the Journal of the Acoustical
Society of America: generally speaking, mammals have larger audible fields than birds and
reptiles, mostly because of our ability to hear higher frequencies thanks to adaptations
of the middle ear around 40 million years ago in the Eocene era. Human hearing isn’t
the best in the natural world, but it’s not the worst either. Thanks to our close-set
ears, we can hear high-frequency sounds; a great adaptation for hearing brief high-frequency
noises — like the rustles made by predators in the woods. Just a guess. As time wore on we eventually got to the 2.1-million-year-old
Australopithecus Africanus, an ancient human ancestor. This hominin had an earlier version
of our hearing systems, and a new study in September 2015’s Science Advances, scanned
the skulls of this and Paranthropus robustus and used the scans to reconstruct a computer
model of early human ears. Turns out, Australopithecus’ and Paranthropus’
physiologies allowed them to hear very differently than modern humans. Back then, we were more
sensitive to Ts, Ks, Fs and Ss in the 1 to 3 kHz range, because savannahs don’t have
things for sound to bounce off of! The researchers think they would have been able to hear these
hard consonant sounds short-range across open areas, which makes sense because these ancient
humans were all about that savannah life. On top of that, Australopithecus and Paranthropus
were better at 1-3kHz than we humans OR our primate cousins are now. By comparison, today, modern humans speak
in the 1kHz to 6kHz range, something these ancient humans wouldn’t have been good at
at all. A 2011 study in the journal Science, used a mathematical model to trace DNA evidence
of human migration and language development, and found verbal communication did likely
originate in Africa; probably in the form of click language. Hard consonant languages
could be 100,000 years old! What if, as we left the forests and savannahs of Africa,
our hearing changed too, and we evolved language to match that evolution! That would explain
why we speak in that 1-6 range today, but these ancient people use the click languages
and spoke in hard consonants, because it was easier to hear. Science is still trying to figure this out,
but what do you think?


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