First the technical stuff. Fingers on the 'down' key everyone...
Me: [dolphins can] <<tell the difference between two metal drums, identical except that their walls differ in thickness by a few tenths of a millimetre.>>
Frank: <<No surprise here. Metal drums are highly resonant, like tubular
bells
or, well, drums. Drums of different wall thickness should have different
resonant frequencies. There should be nothing easier for sonar users
than distinguishing between objects with different resonant frequencies.>>
According to the researchers, this is not what actually happens. Now, I suppose they may be wrong, but they are experts in dolphin biology (which I'm definately not!) so I'll believe them until somebody can demonstrate I shouldn't. According to the researchers the dolphins were detecting the different thickness of the cylinder walls by measuring the delay between the reflected pulses (on the order of 0.5 to 0.6 millionths of a second).
Me: << tell the difference between a fresh fish and one that isn't quite so nice (apparently without using any cues other than what they can tell from sonar)>>
Frank: <<This I+m not so sure about. "Not so nice fish" are most easily identified by taste or smell, senses which work quite well under water for other aquatic organisms. I really doubt that dolphins would show any patience for a research to try to control for this by disabling their senses, and I just don't think the smell could be masked.>>
The researchers claim that this is exactly what they did do. They produced a lot of data to explain how they manage this feat. It certainly doesn't involve just going 'ping...ping...ping...' like a submarine, it's a far more complex procedure involving the modification of six non-linear correlations in the time series (that's how they put it; they're talking about the exact sound of the 'ping') to home in on the target's properties. There seems to be general agreement on this among marine biologists, at least according to the article I read. They added that it was probable the dolphins weren't able to show their full range of abilities in a tank, and they can probably do a lot more in the wild.
</boring technical stuff>
<<There are no examples of even a low level animal society that relies on
sonar for social interaction. Dolphins for example, stay close together in
shallow, well lit water, and probably rely on visual and "verbal" cues as
much as or more than sonar for social interactions.>>
Well, trolls have "verbal" cues too, you know. And yes, I'm sure they do have a pretty good sense of smell. I just don't think that this is darksense.
As for 'shallow, well lit water', perhaps you are unaware that some species of dolphin have eyesight so poor they can only just about tell whether it's night or day? These species live in muddy river estuaries, where visibility is almost nil. They are known to be able to detect objects as small as 1mm across using their sonar.
Before anyone points it out, I know river dolphins aren't particularly social animals (or at least so says my mammal biology book, which Pam has already pointed out is a little out of date). But, as I've already said, trolls have all sorts of other abilities, such as speech, which make them much better at social interaction. I also have no doubt that they have a sense of smell which may tell them of each other's moods; this seems quite likely in a species whose natural environment is perpetual darkness. My point is that your darksense = ranged taste argument seems to hold up no better - and possibly not as well - as the official darksense = sonar descriptions from Trollpak.
<< I don+t know about anyone else, but facial expression does not seem to me
to be
dolphins strong suit.>>
You're probably not a dolphin, then. :-)
Anyway, why assume that facial expression is so important? I dare say
it's part of troll social interaction, but this is not incompatible with also
saying that there are other cues Drosophilla the trollkin can use. Even aside
from the sense of smell (and I say again, trolls probably do have a good
sense of smell, although I don't think it's as good as you suggest), one
might be able to get some information about Crunch the deathlady from, say,
whether she is sending out lots of darksense 'pings' herself, and the nature
of them.
Benedict Adamson (who can probably claim the distinction of being Only Contributor To The Digest To Know 'Trotsky' In Real Life) has already said this better than I would, so I'll just point out another solution to Drosophilla's dillemma:
Trolls are known to have an emotional sub-language (Trollpak p6, p28). Perhaps this is largely under involuntary control? Perhaps its as difficult to avoid using it as it is for human actors to mask their own emotions. Which isn't all that difficult really, but would get Drosophilla out of the pickle you put her in. Crunch is making a deep rumbling noise at the back of her throat... indiscernably quiet to human ears, perhaps, but easily detected by our worried trollkin. Better hide!
<<Hope this makes my concerns clearer.>>
Yes, I think so. I don't really object to your idea per se, I just don't see any need for it. IMO, trolls communicate by means of senses other than darksense, and I agree that smell is likely to be far more important to them than it is to us (regardless of what it says in Trollpak). What I don't see is that darksense needs the kind of radical 'fixing' you propose.
Now, one of my concerns with your theory is how you can use New Improved Darksense to determine distance to objects. This is enough of a problem close up, but according to Trollpak p20, trolls are fairly good at estimating long distances using darksense. This is even a problem if you're trying to sense something fairly smelly, like another troll. Your only clue is the intensity of the whiff, but how do you know the inherent smelliness of the target? People's smelliness is going to vary from day to day, and you don't want to keep bumping into them. This is even more of a problem with something relatively non-smelly like a wall - again, unless you know it is smeared with a precise amount of something odiferous, which is unlikely, IMO.
Also, how does New Improved Darksense detect movement?
Pam Carlson rightly points out that sonar works far better in water than in air, so that bats are a better example of what trolls should be capable of. I feel this is why darksense works better in the dark. In Glorantha 'sound and listening are associated with the element of Darkness'. Now, IMHO an element of Darkness is a nonsensical concept in the RW, but it's perfectly real in Glorantha. I suspect it alters the sound-carrying (or at least ultrasound-carrying - otherwise it would be obvious to humans too) properties of air. I'm sure it does the same thing underwater, which is why Sea Trolls have better darksense than uzko do.
Forward the glorious Red Army!
Trotsky
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