Animal Senses

[mhd]

Your the only one stuck on the x7 thing. The rest of us are talking about the other SOLID numbers like that you refuse to acknowledge have already been given for some reason.

Because that's still one data point for one animal, in one environment (and one that's unusally devoid of distracting smells). Do you really want to extrapolate generic modifiers based on this? One question that would immediately spring to mind is how long it takes the bear to accomplish this task. Is he immediately aware of all kinds of smells within a certain range? Then okay, that might qualify as Telescopic. But if it takes a while for the seal's smell to waft into his direction, then I'd just call that a special case of Tracking that just doesn't depend on a spoor right in front of the tracker.

 

As smell for humans is a bit vague and hard to discuss, never mind that most animals are immensely better at this, I'd be very wary of micromanaging capabilities and applying modifiers.

[TheNaga]

Number of bloodhound olfactory receptor cells = 4 billion

Number of human olfactory receptor cells = 12 million

The surface area of a bear's nose has 100 times more smell receptors than a human nose.

[bigbywolfe]

Number of bloodhound olfactory receptor cells = 4 billion

Number of human olfactory receptor cells = 12 million

That really means nothing to most people and doesn't really doesn't translate to game numbers at all.

[psyber624]

Number of bloodhound olfactory receptor cells = 4 billion

Number of human olfactory receptor cells = 12 million

The surface area of a bear's nose has 100 times more smell receptors than a human nose.

Which would only increase range as a factor of dissipation, which is closer to exponential than linear, so that fact doesn't give a bear 100 times the smelling distance of a human.

[Sean Waters]

Couple of things about smell.

 

1. Even if you are good enough to discern between which nostril gets the smell first, smell is VERY heavily dependent on air current.  It is not unusual for the family to be sitting in the living room and for the dog to fart.  Who gets the smell first (sometimes who gets the smell at all) depends entirely on the route the smell chemicals in the air take.  This is why dogs cast about: they are triangulating.

 

2. Scent detection is not practically instantaneous, like light or sound.

 

3. I have looked this up and, do you know, no one is quite sure how smell works, whether there is some sort of receptor site or whether the nose somehow picks up scent vibrations.

 

4. One huge advantage a human has over a bear is that they can train their senses, so a wine buff can tell you where a wine is from.  His sense of smell is not necessarily better than yours, but he has spent a lot of time training himself to recognise differences (which you could do with a KS as a complimentary skill to Perception.  Bears are not going to do that.  They hate wine.

 

5. As psyber624 says, range and dissipation matters.  So, dissipation matters: assume that scent dissipates in all directions equally, the density is inversely proportional to the cubed root of distance (as volume works with cubes.  So, if a human could smell something at 10 metres, then a nose that is 100 times more sensitive (i.e. can detect a concentration of 1/100 of that) could detect the same smell at the cubed root of (10x10x10)x100, or 46 metres. or about 4.6 times the distance that a human can detect the smell.  It is probably not quite as simple as that but it puts it in perspective.  If a bear can scent something at 20 miles, then a human can scent the same thing at about 4.3 miles.  That is going to be a strong smell...

 

NB smell probably does not diffuse in all directions equally, but even if we just work with area i.e work with squares not cubes, you are looking at about 10x the range.  It is only if the smell only diffuses in a line that you get the range up to 100x, but that is not really accurate: that is not diffusion at all: unless the smell particles are constantly accelerating they will stay the same distance apart i.e. their density on average will not change, so if you could detect the smell near to the source then you could detect it anywhere along the line it diffuses along.  That is clearly not what is happening.

 

6. I have no idea how long smells 'live'.  I doubt that is too much of a factor in this discussion, but some scents probably have a very short half life.

[Sean Waters]

That really means nothing to most people and doesn't really doesn't translate to game numbers at all.

 

Good point.  4 billion is 333 x 12 million.  333 is more a number I can get my head round

 

Assuming that diffusion is equal in all directions that still only means about 7x the range of a human nose, based on concentration.

 

Of course there are threshold cases, not just range issues: instances where, even at no effective range, or a couple of centimetres, the scent falls below human perception values.  In that instance a human could never small that concentration of scent, but a more sensitive olfactory organ could.  There are some things humans can not smell at any range that bears or bloodhounds can.  There may also be certain things that one nose can smell that another can not, for example I think there is a genetic marker in humans that allows some of us to smell certain scents but not others of us, even though there is no difference in sensitivity to a second smell.  I think violets or possibly asparagus may be an example, but I can not now recall.

 

Think of this in light human sight: our eyes are better than most dogs eyes, but they can see further into the UV than we can.  The fact we might have more receptors is never going to let us see something that is only emitting UV, whereas a dog can see it.  I don't doubt the same applies to scent: there will be some things dogs and bears can smell that we just can not (and vice versa) because that is how our noses work.