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Re: Polar Bear Challenge for AAH opponents
Phillip Bigelow (n8010095@henson.cc.wwu.edu)
Sun, 25 Dec 1994 03:31:12 GMT
patdooley@aol.com (Pat Dooley) writes:
snip...
>My personal experience is that I can hear underwater but the sounds are
>different. How does human underwater hearing compare with Bonobo
>underwater hearing?
It compares quite well. The auditory bones in humans show no
specializations for underwater hearing. Both species of Chimpanzee also
show no specializations for underwater hearing. Specializations that would
be expected would be: 1) sinus cavities around the tympanic bone, that would
enhance reception of a wider range of frequencies underwater. 2) Greatly
inflated tympanic bone, which would give a greater "resonating chamber" for
low-frequency reception. There are other specializations that would be seen
in the auditory region that are absent in both Chimps and humans. None of
these characters are found in the lineage (clade) Anthropoidea. So, Chimps
and humans only hear so-so under water. Not horribly, but not that good,
either.
My references for what specializations to expect in the auditory region
of aquatic mammals are:
Repenning, C.A. and Tedford, R.H., 1977. Otarioid seals of the Neogene.
_U.S. Geological Survey Professional Paper_ 992, pp. 1-93.
Mitchell, E., and Tedford, R.H., 1973. The Enaliarctinae, a new group of
extinct aquatic carnivora and a consideration of the origin of the
Otariidae. _Bulletin of the American Museum of Natural History_,
151, pp. 201-248.
<pb>
>>2) Humans are quickly suseptable to hypothermia in both cool and warm
>water.
>That is something of a myth. For example, Korean and Japanese female
snip...
Now do you see my point? (made in a previous post).
We are debating the accuracy of each other's
lists. :)
<pb>
>Strong arches imply stiff feet - just like flippers.
snip...
Strong arches are specializations in hominids. Hominids from A.
afarensis onward show this trait. Biomechanically, it is needed only
in flat-footed animals that are dependent on walking on land. The
purpose of the arch is to act as a "spring", to absorb the shock of
walking long-distances. In elderly people who have fallen arches,
they cannot walk very far without leg pain or back pain. Just check
out the popularity of arch-support shoes for people who stand at lot
on the job. Untreated, fallen arches lead to back problems later in
life, because the "stance" of the person changes when they have this
affliction.
Strong arches do _not_ imply stiff feet. Human runners who have
stretched properly prior to running, can bend their foot upward toward
the shin such that the bottom of the foot makes a 30 degree angle with
the shin. An aquatic mammal doesn't need such mobility in the foot,
because running is not a concern. Keep in mind that it is the _ankle_
that is important in flat-footed locomotion on land, _not_ the toes.
Flippers, on the other hand, are stiffened in the ankles (and/or
wrists), as well as the phalanges. Stiffening makes a stronger
"paddle". Arches are absent on marine mammals and the higher apes.
My source for this information (except for the data on the aquatic
animals) came from:
Stern, J.T. and Susman, R.L., 1983. The locomotor anatomy of
Australopithecus afarensis. _American Journal of Physical
Anthropology_, v. 60, pp. 279-317.
Johanson, D. and Edey, M. 1981. Lucy. The Beginnings of
Humankind. Simon and Schuster, New York.
<pb>
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