Re: Aquatic ape theory

Phillip Bigelow (
3 Oct 1995 16:22:08 -0700

VINCENT@REG.TRIUMF.CA (pete) writes:

>Phillip Bigelow ( sez:

>` (H.M. Hubey) responded:

Regarding the discussion of what character traits a purported "aquatic ape"
would need to help it avoid predation while in the water, I wrote:

>` Yup, but our hearing is STILL worse in water than it is in air.

>Hmm, I don't know why you would say this. Any creature's hearing
>is much better under water, because of the way sound travels
>through water. I've never noticed any difficulty hearing and
>locating sounds underwater. And I can hear a power boat long
>before it sounds above water.

It depends on what you means by "better hearing". It is true that certain
frequencies of the sound spectrum are much louder under water, but that
doesn't necessarily mean that your hearing is more acute underwater than in
air. And that was the point that I was making.
Human hearing under water is, overall, poorer than in air. It is
akin to placing empty tin cans over your ears, and then trying to listen to
a piece by Bach. You will notice that the sound appears to be louder, but
you will also notice that the loudness is also detracting from the
quality of the concert. You will also notice that a lot of instruments will
appear to "drop-out" (loss of certain frequencies). The same thing happens
to human hearing under water. (and yes, I have tried the tin-can-over ears
experiment at a Bach concert, and yes, I did look quite handsome while doing
it). But least it was louder, right?? :-).

pete continues:
>The sound is often so clear
>that I'm fooled into thinking a boat is close approaching
>when it turns out to be still half a mile away.

That is what I meant when I wrote that humans have poor directional acuity
for sounds produced under water. "Sonic depth perception" is a major
problem for SCUBA divers when they are listening for power boats. Why do you
think there are so many collisions between power boats and surfacing SCUBA
divers along many crowded beaches?
p.s.: You wrote that you can hear a power boat from quite a distance away
while you are submerged. Can you also hear the approach of another totally
submerged swimmer? Because, these imaginary "aquatic apes" would have had to
contend with totally-submerged crocs that approach from below, not from power
boats that skim the surface.