Actually, there are a few cetaceans that have a higher brain mass to body
mass ratio that humans. The dolphin is one of them. The dolphin also has a
more convoluted brain than humans. They exhibit complex intelligent speech
patterns as well.
I disagree about the signal processing issue, though. Cetaceans have
excellent audio capabilities, but mediocre, non-stereoscopic vision and
vision processing. Humans have mediocre audio capabilities, but very good
visual processing capabilities. Humans receive something like 90% of their
sensory input through their eyes.
I used to work on DSP applications, mostly audio, but occasionally graphics
oriented. Visual processing applications almost always require an order of
magnitude more processing power than audio ones. I have heard the argument
before, but I have a difficult time believing that cetaceans use more of
their brain for audio processing than we use for vision. State-of-the-art
audio rendering software can run in realtime on a processor capable of less
than 200-mips.
Also, our hearing is more capable than most people think. I have seen
experiments where blind people were able to echo-locate objects with a cross
section of 1 square inch in a room using their own voice, and could detect
changes in position of 3" at a distance of 15' of objects with a
cross-section of 1 square inch. Non-blind people tend to only have a range
of 3-7', but everyone possesses the capability. I actually took one of
these tests. My effective range was 5-6'. Most people don't know they can
do it until they try.
-James Rogers
jamesr@best.com